What is a Herbarium and what is it for: Jamestown's famous weed

Today for my blog post I figured I would do a traditional blog post (for this blog, anyway) along with a "Part 2" that talks a bit about what a Herbarium is and what use it has to science. I've been talking a bit in recent blogs about my personal herbarium that I'm making with my Garden List species, and I've also done a few for the Herbarium at Western of species I've found on campus that only recently appeared. I'm a creature of habit and tend to walk the same path to go to the same place; because I happen to pay attention to the "green stuff" covering the ground, I usually notice when something weird pops up that wasn't there before. I'll talk a bit about one of my favourite weedy plants, which also happens to be my very first plant collection in the herbarium! Sandra, who I featured in a sneaky picture in a previous blog post HERE, is the Herbarium Assistant and Acting Herbarium Curator until the position is filled and she found it hysterical how excited I was about collecting and pressing my very first Herbarium specimen. Since then...I'm hooked. Anyone want a plant collection pressed and dried? I'm your girl. Even better (because it's more fun), want a pressed and dried collection glued and mounted on herbarium paper? Let me know.

Here we go! My favourite weed. :)

Species name: Datura stramonium

Common name: Jimson weed, Jamestown weed, devil's cucumber, datura

Location: UWO Campus

Jimsonweed (or Jimson weed...same plant, along with about 20 other common names this plant has) is my favourite weedy species that we have here in North America. Not just because of it's many common names (HOW AWESOME is the name "devil's cucumber"?!), but because of the rich history it has in the making of the identity of North America today. Without this plant, I doubt anyone living in the United States or Canada would have the same kind of "national identity" that we have today. This plant is widely believed to have originated in North America, but was spread across the globe very early for its recreational uses and so that's difficult to confirm. Since I really like this plant, I'll give it the benefit of the doubt and say it's native to North America...because I can :) It can be weedy and spread quite quickly, so if you do decide to plant it you'll want to make sure you dead-head the flowers before the seed pods form (or, if you like the appearance of the seed pods make sure you pick them off the plant before they crack open and disperse their seeds).

Jimsonweed is in the nightshade family (Solanaceae), which is the same plant family that we find the edible food crops potatoes, tomatoes, peppers, and eggplants, as well as some ornamental species like henbane, mandrake, belladonna, and deadly nightshade (which, contrary to its common name is actually one of the plants that's least likely to kill you in this family, unless you're a small child or a beloved family pet). Like many of the species listed above, this plant is deadly poisonous. And when I say deadly, I mean deadly. Consuming the seeds from one seed pod would be enough to cause catastrophic organ failure in an adult human which would very quickly lead to death. Should you decide to only consume a few seeds, maybe 25 or so, it would also lead to catastrophic organ failure. This circumstance, however, results in a very slow, very painful death as your body slowly shuts down. Consuming only a small number of the seeds of this plant *may* result in a hallucinogenic trip, but it has equal likelihood in resulting in nausea, vomiting, diarrhea, dehydration, and you wishing that the world would end right then and there (but you'll live). A few years ago there was a string of deaths of high school students in the United States, and it turns out that they all died from consuming Jimsonweed seeds. One of their friends had read on the internet that they're a free way of getting high, so they all ate them. Kids, don't believe everything you read on the internet! This plant is not worth it...trust me. Jimsonweed is fun to look at (how awesome are those seed pods?!), the flowers have an absolutely wonderful aroma, and they provide some nice fall colour to a garden. But don't, under any circumstances, eat it. Ever!

So why did I say above that this plant is probably the single most important plant species for the development of the identity of North America as it is today? Well...it comes from this plant's other major common name, the Jamestown weed. This name comes from Jamestown, Virginia, which was the site of Bacon's Rebellion. Long before Europeans sailed across the ocean blue to settle in what is now the United States, there were people already living there. In fact, there were a lot of people. About 14,000 people lived in and around Jamestown in the early 1600s when the first wave of settlers arrived. The local people were used to the types of harsh conditions to be expected in the winter months, but the Europeans were not so lucky. Many of them died, and it is widely speculated that the few that remained turned to cannibalism in order to survive. During the second wave of settlement, the "new Americans" were smarter: use the locals to build us shelters and show us how to gather food, and kill them if they refuse. There were many clashes between groups, resulting in hundreds of deaths. Nathanial Bacon decided he had had enough of the British fighting with the local people, and started an uprising. Governor William Berkeley had started teaming up with the local people to start building a nation. This angered some of the early settlers, since these same people were responsible for the deaths of many of their friends and family (it swings both ways, but I guess that wasn't the point). Bacon gathered people (estimates are between 300 and 500 people) to fight against Berkeley, eventually driving him out of Virginia and back to Britain. One of the major turning points in the rebellion was when British soldiers started flipping sides and fighting against their countrymen and their own Governor...all because they had been drugged. Bacon observed the local people preparing tea made out of a benign green plant (likely some kind of mint or other species which has a strong flavour, since Jimsonweed is reported to not taste very good) and sprinkled with 2 or 3 of the seeds of the Devil Plant. He prepared this same tea to offer to the freezing British soldiers, who promptly hallucinated for two weeks and became violently ill. While hallucinating, the soldiers were manipulated into amusing Bacon and his supporters, and once the drug's effects wore off they returned to normal, confused as to where the time had gone. When they were ostracized by their fellow soldiers for the actions performed while "under the influence," they decided to flip sides and help drive Governor Berkeley out of their new settlement. Berkeley retreated across the river, but with Bacon's death in 1676 a new leader of the Rebellion took over: John Ingram. Unfortunately, Ingram wasn't a very smart man. He decided to start a fight against the Pamunkey people, which were loyal supporters of Berkeley and even supplied him with warrior fighters. Between the British and the Pamunkey, the Rebellion was defeated and the rebels were driven out of the new settlement. The "good guys" had won. It has been speculated that if the British soldiers drugged with Jimsonweed hadn't flipped sides, Ingram never would have had enough supporters to wager a war against the Pamunkey people. Without this pivotal attack, Berkeley might have decided the war wasn't worth it and retreated back to Britain. What would this side of the world look like if this had of happened? It's impossible to speculate, but I bet it would be very different than what it is today. All thanks to a plant.

Jamestown, Virginia actually has an incredibly fascinating history in the early settlement of North America, and the independence of the United States. If you'd like to read more about the waves of settlement, the clashes that occurred, and the REAL story of Pocahontas (yes, that happened in Jamestown, too!) you can read more on the Wikipedia page HERE.

This plant isn't all bad. The active ingredients leading to hallucinations (and ultimately death) are alkaloids called atropine and scopolamine. Some of you might recognize these two compounds, as atropine is one of the most successful drug compounds used in treating severe asthma. In large amounts, atropine causes the paralysis of the lung tissue and the dilation of the bronchioles which increases air flow. In smaller amounts the paralysis occurs to a much smaller extent allowing the patient to still be able to breathe, but dilates the bronchioles to increase air flow. Scopolamine is also a very important drug in modern medicine; it's used to treat symptoms of Parkinson's disease and is one of the most effective anti-tremor medications (in small concentrations, of course!). Datura itself (the combination of these two alkaloids) is used to treat morphine addiction. Because of the effects on the body that it has, there are certain conditions that it will aggravate like glaucoma or difficulty urinating. Glaucoma is caused by an increase in pressure of the fluid of the eye, which can be aggravated by atropine (which causes the dilation of blood vessels, which would increase blood flow to the eye and increase the pressure even more). One of the main effects of both atropine and scopolamine is the inhibition of the parasympathetic system, which is responsible for the regulation of urination. If you're already having trouble urinating, inhibiting this further could be disastrous. But, again, this plant WILL KILL YOU if you try to make some kind of medicinal concoction on your own. Prescribed drugs have these compounds in very small, controlled amounts. The plant does what it pleases. Don't be stupid.

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Now that you know why this plant is just so awesome, I figured I would talk a bit about this "Herbarium thing": what it is, what it's used for, why they're important, and what is stored in them.

A herbarium is like a library, but for dried plant material. When you walk into a herbarium (which is climate-controlled to prevent insect infestation, so usually kept around 15 C) the first thing that you'll notice are rows upon rows of cabinets. The cabinets contain stacks of sheets of card stock, on which is glued (or sewn, if you've got a really old collection) a plant collection. This collection is identified by species name, a location of where the collection was made (which now includes coordinates), any important information to go along with the collection, who made the collection, and a collection number (often called an accession number). Herbarium specimens are very similar to books: they have titles, authors, years of publication, and a brief description (like liner notes) of what can be found on the page. These specimens are then preserved for all of eternity, and databased so they can be accessed by researchers from other institutions. Some herbaria have thousands of collections (the Western Herbarium has about 60,000 collections), while others like the New York Botanical Gardens or the Paris Natural History Museum have millions of collections (about 10 million at NYBG, 8-9 million in Paris). Herbarium collections are invaluable to science since they show a snapshot of the plants living in an area in any given period of time. The herbarium collections at Western are "young" compared to other institutions since our oldest specimen is from the late 1800s. For my research, the oldest herbarium specimen I received on loan was from 1799, and many were from the 1820s and 1830s. There are some collections in Kew and in Paris from the 1500s! Herbarium specimens have been used in a wide variety of different types of biological studies, from studies about taxonomy (where you study old and new collections of species to look for new species "lost" in herbarium collections or to help you determine whether what you collected is a new species or not) to conservation biology. Herbarium specimens are actually becoming more and more crucial in conservation and restoration biology as habitats are becoming more and more degraded. What plant species used to be present in a given area, compared to what is there today? Can species that used to be present even be located in the same area now? Has the composition of which species are present completely changed? What does this mean? There have even been cases of determining that a plant species is now extinct in the wild based on herbarium collections. The species was collected from an area, described, and hasn't been seen since.

So how do we make a herbarium collection? I figured it was only fitting that my very first plant collection ever to be stored in a herbarium should be my favourite plant: Jimsonweed. When I found the plant growing on campus I carefully pulled it out of the ground to get the root ball intact, knocked off all of the extra dirt, and brought it in to Sandra in the herbarium for pressing. Here's what the plant looks like, in front of a standard piece of herbarium paper (11.5" x 16.5") for scale: 

Now, it should be obvious even to someone who's never made a herbarium collection before that this isn't going to work. Half the plant is missing; it's about 2 times bigger than the size of the paper. So what to do? Well...cut it. All of this preparation of a specimen needs to be done before it's dried, or else the dried plant will just shatter when you try to manipulate it later. I cut the bottom off right at the edge of the paper, and the bottom half became "sheet 2 of 2" for this collection. Next, the collection needs to go between pieces of newspaper and pressed out flat in a herbarium press, which then goes in the dryer to dry the specimen as much as possible (which can take up to a month, depending on how juicy the plant material is!). When a collection is pressed, maintaining the integrity of the plant is very important, because if someone wants to see your collection in 60 years they have to be able to determine what it even is. Showing the upper side and the lower side of leaves is important, but never the same leaf. Folding leaves when drying makes them very fragile and should be avoided when possible. The flowers of the plant, if present, should be kept as visible as possible and all other plant material should be pulled away. The seed pods, if present, should remain on the plant and should also be easily visible. Once all of the manipulation is done, put the newspaper-plant-sandwich into the press, the press into the drying oven, and forget about it for at least a week.

Once the press comes out of the oven, the sheets of newspaper can carefully be removed and opened. Sometimes tweezers can help to carefully pick the newspaper off of the plant material, since sometimes plants "juice" when they're squeezed into a tight location like the herbarium press. As long as the collection is dry, it's ready to be mounted on herbarium paper.

Grab yourself some 11.5" x 16.5" rag-bond acid-free paper and some acid-free glue. Contrary to what you might think, the less glue the better (learned that one the hard way once...). Decide which side is "up" and which side is "down" of your collection, and dab some glue in important places on the side that will be down. Important places would be at major intersections on the stem where pieces could break in two, along leaf petioles, or where the flower attaches to the stem. One thing you DON'T want to do is glue the entire flower to the paper, or the entire leaf. When someone else looks at your specimens they like to be able to see the underside of all of these things, so leave some space where they could carefully be pulled up off the paper to inspect the underside. When all of that is done, the specimen needs to be weighted down onto the paper. Herbarium presses might be able to squish things pretty well, but some plants are great resistors to the squishing. No matter what you do, you just can't get them quite flat enough. Common washers and nuts can be used to weigh the plant material into the glue dabs until the glue dries enough that the plant can't escape it. Once it's all glued and weighted down, it looks like this:

Let the glue dry, and while you're waiting you can make yourself a label! The label needs to be laser-printed using acid-free ink on acid-free paper that is BRIGHT white (even brighter than normal printer paper) and needs to be formatted according to the herbarium that you're depositing your specimen into. This is what our herbarium labels look like, and all of the information that we put onto them:

(my collection is #53,018 in the herbarium! Woo!)

Now it's time to glue the label onto the herbarium paper. They always go in the bottom right corner, so hopefully you saved space for it there (again, learned this the hard way once, too...). Glue it on with acid-free, extra-tacky label glue (which, of course, is different than specimen glue...). Make sure the glue doesn't leak out the edges! If it does, wipe it off right away. We want these looking pretty:

And now you can do any finishing touches! You can see that there are four of the big nuts weighing something down above the label on the sheet on the left. When the seed pods of Jimsonweed are dried, they split open to release the seeds. We want to keep these! Any plant material that falls off of a pressed herbarium specimen is still important material. These go into a little paper envelope, which is glued directly above the label of the specimen (or on page 1 of 2, if there is more than 1 sheet that goes with a single collection).

Now you're done! I was so proud of this silly specimen. It's just a dried plant glued onto paper, but it was my first dried plant glued onto paper! And hopefully it will be useful to someone some day. Now I've got nearly 90 others courtesy of my Garden List and trust me...botanical craft time never gets old :)

Green tea: won't cause you to lose weight or prevent cancer, but tastes good!

Species name: Camelia sinensis

Common name: tea plant, tea tree (see below for why you should never call this plant a tea tree), tea shrub

Location: teaching lab at Western

For the last "Plants as a Human Resource plant profile," I figured I would do one of my favourite plants in the world, and one that I exploit multiple times per day: the tea plant. The tea plant (often referred to by it's Latin genus, "Camelia") is native to China, as are all plants with the species epithet "sinensis" (it means "from China"). There are two major varieties of tea plants: one that was domesticated in India and the Middle East called Assam tea (C. sinensis var. assammica), and the other that was domesticated in China and known as Chinese tea (C. sinensis var. sinensis). There are two other recognized varieties but these are only used locally for tea, not shipped to international markets. If the tea you buy is just referred to as "tea," you can be almost guaranteed that it refers to Chinese tea, as Assam tea is almost always specified on the label. It does have a slightly different taste, and when the leaves are cured it brings out the difference in flavour. It would be appropriate to note here why I say above that the term "tea tree" should probably not be used to refer to this plant, despite the fact that it can reach "tree height." When you call something a tea tree, most people think of an essential oil that is referred to as tea tree oil, used in cosmetics and in fragrances (sometimes now used medicinally in herbal medicine, too). This is NOT the same species, and this extract is from the leaves of the tea tree plant, or Melaleuca alternifolia. Please don't drink tea tree oil...your digestive system will hate you for it.

One thing that catches many people off-guard is that ALL types of tea (black, white, green, yellow, oolong, and pu'erh) come from this plant. The way that the leaves are treated after picking is what determines what type of tea the leaves will become. There are also differences in when the leaves are picked, and how many are used in the making of different types of tea.

Black tea: leaves are picked and then allowed to fully oxidize. The leaves are fully oxidized when they turn black and start to roll inwards. The leaves may then be dried and packaged (being cut before or after drying, or left whole), or they may be flavoured before drying. Earl Grey tea has bergamot flavouring added before drying (bergamot oil is extracted from the skin of the bergamot orange), English breakfast tea is made up of plain black tea leaves, Irish breakfast is a blend of Chinese and Assam tea leaves, and Masala chai is a blend of black tea leaves and other spices (and often sugar).

Green tea: the newest leaves are picked, rolled, and immediately dried with minimal oxidization. This allows for a much milder taste, and a taste that blends well with other flavours for tea blends (like dried fruit pieces or other mild flavourings like flower petals). The quality of the leaves, the amount of time they are given to develop on the plant, and the environmental conditions the plant was subjected to during growth all play major roles in the flavour of the tea. Lower-quality teas have a much more bitter after-taste to them than higher-quality teas, and if you compare a good quality green tea to a poorer quality green tea in a taste test you'll be able to tell the difference right away. Because of the lack of oxidization of the leaves, this leaves all of the chemicals intact that many claim have health effects (more on that later).

Matcha tea: this is just a specific cultivar of tea plant where the leaves are dried without oxidization and then ground into a powder. This powder is whisked into warm water until a frothy-like consistency is reached, and then consumed. Many proponents of green tea having positive health effects say that matcha has a much larger effect on health because the leaves themselves are also consumed (unlike drinking traditional green tea).

White tea: this is a special type of green tea, where the leaves are allowed to wither on the plant before they are picked and dried. This prevents the oxidization process, but the leaves are "bleached" on the plant so they are nearly white in colour. This is emphasized by the fact that the leaves are very young and still have a dense covering of white hairs, which make the leaves look even lighter in colour. The term "white tea" does not refer to the colour of the beverage, just like "green tea" doesn't refer to a beverage that is green. If you get a cup of white tea that looks like water...you've just been served water. If you get a cup of green tea that is green (and it's not matcha, which is bright green in colour), you've been served a cup of bad quality green tea and green food colouring.

Yellow tea: this is a relatively uncommon type of tea, where the leaves are allowed essentially to rot slightly while being dried very slowly. This gives the leaves a yellow-ish appearance, and gives a very different flavour to the tea. I have yet to try yellow tea (or see it for sale in many places) myself. Sometimes the term "yellow tea" is used to refer to tea that is either green tea or white tea that is served in the Imperial court (just to make things more complicated).

Oolong tea: this type of tea is almost an intermediate between white tea and black tea. The leaves on the tea plant are allowed to wither during extreme sun exposure during the hottest months of the year, then picked and fermented (not fully fermented like black tea, but fermented enough to give a smoky and full-bodied flavour). The amount of fermentation depends on the quality of the leaves picked, and in some areas in China only one specific cultivar is used to make oolong teas. The withering of the leaves causes them to curl and twist, so watching oolong absorb water during steeping is often a sight to be seen. What looks like tiny little fragments of tea leaves actually unfurl into complete leaves. It's like magic!

Pu'erh tea: this is a type of tea produced exclusively in Yunnan Province in China, and it is made by fermenting and oxidizing the leaves of the tea plant after drying. This gives the leaves a very unique flavour which is difficult to describe, but also allows for customized fermentation and oxidation prior to shipping. The leaves are, more often than not, packaged in "cakes" to be sold and wrapped in decorative foil. This actually allows for the continuous oxidation and fermentation of the leaves during shipping and storage, which is referred to as "aging" the tea. Sometimes tea cakes are shipped immediately and may be aged by the purchaser or used right away (the flavour, and colour of the steeped tea, differs drastically depending on amount of time left to age). Other times tea cakes are allowed to age at the factory, then shipped. These are usually consumed immediately, and are very expensive to buy. The cakes are packaged with "tickets," that are always stamped with a four-digit number. The first two of these numbers represent the year in which the recipe for that specific type of pu'erh cake was developed, the third number refers to the grade of the leaves used (the smaller the better), and the last digit refers to the specific factory in which it was made. To use the leaves, they are often just chipped off the cake until the desired amount is separated, but sometimes the entire cake may be steamed to loosen all of the leaves (and then they would be stored in an airtight container after re-drying). Often a pu'erh knife is used to loosen shavings of leaves from the outer surface; you never take a "slice" of a pu'erh cake because the amount of fermentation and oxidation from the outside to the inside of the cake differs drastically. Sometimes pu'erh tea can taste "fishy" if it is fermented or oxidized too quickly, which is often a sign of poor quality. Choose your pu'erh wisely!

Onto the health effects of tea. For the most part, black tea might be a tasty beverage but it is almost entirely lacking in the polyphenols that tea is known for. If you want to drink tea to be healthy, put the Earl Grey and English breakfast back on the shelf and find yourself a good-quality green tea. There are four diseases or disorders that tea has been shown to have proven positive effects, as demonstrated in large-scale clinical trials. The first is in calming the symptoms of asthma. When green tea is consumed on a regular basis it can act as a bronchodilator, which would increase the air flow to the lungs. This does NOT mean that if you're having an asthma attack you crack out the green tea and make yourself a cup. "Green tea therapy" for asthma is used in conjunction with emergency inhalers and also the everyday inhalers; the idea is that asthma attacks will occur less often, be less severe, and everyday inhalers could be at lower doses and be used less frequently. The next three diseases all have to do with dilating the vascular system; regular consumption of green tea has been shown to help decrease the severity of angina, peripheral vascular disease, and coronary heart disease by increasing the diameter of the blood vessels, allowing for better blood circulation. This definitely won't cure any of the above diseases or prevent you from getting them, but if you are at high risk of developing any of them then it may help prolong the onset (or decrease the severity of the symptoms). That being said, the number one and number two risk factors for all three of those disease are no longer related to inheritance from your parents; they're now obesity and smoking. So do yourself a favour and quit smoking and get out and exercise!

There are a lot of other claims out there about the health benefits of drinking green tea, but so far none of them, I'll repeat that in big letters, NONE OF THEM, have been demonstrated to be true in large-scale clinical trials. People will tell you drinking green tea regularly will decrease your cholesterol and prevent the onset of cancer, neither of which have been demonstrated. Extracts from the tea leaves from the plant (the key here is from FRESH leaves. Are these chemicals still there in quantities that are useful to the body after drying and then steeping in boiling water? Unlikely) have been shown to have anti-cancer properties and the ability to reduce cholesterol but these effects have never been demonstrated in humans. There's also the strong suggestion that drinking green tea will contribute to weight loss, which I find incredibly hard to believe. Any kind of caffeine intake will "contribute" to weight loss if you don't take in more calories than you burn, because caffeine is a stimulant. Will drinking green tea specifically cause you to lose weight? No. Exercise and burning more calories than you consume causes you to lose weight. If you want to lose it, you need to put in the effort. Don't fool yourself into thinking you can drink some tea or take a pill made of green tea extracts and the pounds will melt off.

So are there any benefits to drinking green tea, other than the four mentioned above? Well, the jury's still out. There's evidence that the consumption of green tea SHOULD be beneficial, but nothing has been proven yet. That being said, there's absolutely no evidence that green tea is harmful to you, and if you're concerned about pesticide use there are now an over abundance of companies that produce organic green tea. Just don't go overboard; remember that tea does contain caffeine (although much less than coffee), and if you're drinking it to be healthy you can't be adding milk (or worse, cream!) or sugar. Learn to love the purity of the leaves :)

There's Rosemary, that's for Remembrance

Species name: Rosmarinus officinalis

Common name: rosemary

Location: teaching lab at Western

Rosemary is an incredibly unusual plant in the mint family (the Lamiaceae) because of its almost cactus-like lifestyle. The Latin name of this plant actually comes from its unusual ability to acquire nutrients in a hostile environment: "ros" for dew, and "marinus" for ocean. Not only is this plant incredibly salt-tolerant (with much of its native range in marine spray habitat), but it can acquire almost all nutrients it needs to sustain life from the air, where droplets of dew condense on the hairs and waxy coating of the leaves, where they are absorbed and used by the plant to make energy. In fact, rosemary is so drought-tolerant it can go without being watered for months. This makes me seriously wonder how I managed to kill my rosemary plant in a single month; something tells me I over-watered and should only have been misting it. It was one of those strange rosemary Christmas trees, so it might have also been root-bound. Yep, let's blame it on being root-bound. Then it's not my fault. :) Rosemary is native to the Mediterranean, where it still commonly grows in the wild. It is also a popular ornamental species, and some rosemary plants are hundreds of years old.

Rosemary is one of the most popular herbs to use in cooking, especially in meat dishes because it has such a distinctive flavour. In fact, what most people don't know about rosemary is that the flavour is best brought out of the herb when you "spank" it (for a refresher on why you might want to spank an herb, refer to my blog post about mint HERE) and then burn it. Yep, that's right. Burn it. One of the best ways to use rosemary is on barbecued meats where you poke some sprigs of rosemary into the meat and just let them singe and burn until the meat is cooked to desired done-ness. Take the burnt pieces out of the meat with some tongs before serving (or just eat it. Burnt rosemary won't kill you), and voila! Smoky rosemary-infused meat. Yum, yum. Rosemary also pairs really well with mustards, because the acidity in the mustard also brings out the flavour in the rosemary leaves. Interestingly enough, mustard is native to almost the same geographic region that rosemary occupies. There might be something to this mustard-rosemary pairing...

As the Latin name suggests, rosemary has been used for centuries (some people have argued for many millennia, but the evidence for rosemary use only dates back to about 3,000 years ago. Yeah, "only.") as a medicinal plant, mainly to improve memory. It wasn't just used to improve "brain memory," either, but also to improve muscle memory. After someone suffered a stroke in the Middle Ages, a salve of rosemary leaves ground into wine was applied to the site of muscle paralysis as it was believed that doing so would help the body "remember" how to move the paralyzed muscles. It probably didn't work very often, but at least you would smell good :) That type of concoction was also consumed orally to treat gout (it was most famously used in this manner to treat the Queen of Hungary Elisabeth of Poland in the 1300s). Don Quixote also used rosemary leaves in his miraculous balm of Fierabras, which was reported to heal anyone that drank it. This very likely had at least SOME effect on the body, as the secondary compounds of rosemary are highly antimicrobial. Back in the 1100s and 1200s, before the discovery of penicillin, any kind of wound that got an infection would almost certainly lead to death. By either drinking this highly antibacterial (and antifungal) beverage or applying it directly to the wound, it would help protect it from infection. For some wounds it would have been irrelevant as they would be severe enough to kill you anyway. But for other more minor wounds, it might have made the difference between life and death. It's always nice to know when some of the folklore of popular tales is actually biologically possible!

Because of its historical medicinal use in improving memory, rosemary sprigs also play a leading role in wedding and funeral traditions around the world. In funeral bouquets that are scattered on graves, rosemary serves as a sign of remembrance for the dead and a way of honouring their memory. Across much of Europe, rosemary is still incorporated into the wreathes in Remembrance Day ceremonies, and also in war commendation ceremonies (especially if these are to commemorate the brave acts of a soldier who died in battle). In wedding ceremonies, they represent remembrance of loved ones that passed before the time of the ceremony and also to remember the life the couple spent apart before they were united in marriage. This eventually caused the evolution of rosemary from an herb of remembrance into an herb of love, and now sprigs of rosemary are considered to mean love and good luck in marriage. The sprigs of rosemary in the bride's bouquet would be planted in the ground, and if they grew it would be a sign of good prosperity and good luck. If they didn't grow...well, I guess it sucks to be you. Hint: dip it in some rooting compound first and problem solved. See, there's always a way to coerce luck into working out in your favour. Just takes some work!

Mints on Monday

For this blog, like the blog post I wrote about different species of geraniums (which you can read about HERE), I'm going to profile 4 different species (well, two species and two hybrids; sometimes only one species, two hybrids and one variety depending on who you ask) of mint. These plants are all in the genus Mentha, which is the "true" mint genus (there are other groups that are called mints but that are not in the genus Mentha; these would be close relatives of this genus that would be in the mint family, the Lamiaceae). The four types of mint I'm going to profile are: orangemint, menthol mint (or peppermint), spearmint, and mojito mint. The photo below is a photo of all four of these plants on display in the teaching lab:

You'll notice that I conveniently numbered all of the pots in the order I'm gong to profile the plants :) I love it when I plan ahead. So let's begin!

Species name: Mentha citrata (sometimes Mentha arvensis var. citrata)

Common name: orangemint

Location: teaching lab at Western

Orangemint is sometimes only known as a variety of water mint (Mentha arvensis), but I like to consider it a separate species. Currently, whether it's a species or a variety is still up for debate since DNA studies can't quite rule out either option. Mints are notorious for being able to cross-pollinate each other regardless of what species they are, so there is a lot of genetic contamination of most "wild" populations, and greenhouse populations (unless bred to be sterile) are no better. Due to the huge difference in texture and shape of the leaves, I like to think it's a separate species. It's likely native to the Mediterranean (although this is debatable since it has been cultivated for so long in so many other locations it's hard to tell), and is potentially invasive in some areas (but not southwestern Ontario where I am).

So what is different about the texture and shape of orangemint leaves? Well, for one they're rounded. The reason why "spearmint" is called SPEARmint is because of the shape of the leaves: almost all leaves in the genus Mentha are very pointed at the end and have sharp teeth along the edges of the leaves. Right away this plant is definitely an oddity in the genus. The leaves are also much fleshier than other species of mint, and have a bit of a water storing capacity even if they aren't true succulent plants. This characteristic makes orangemint pleasant to eat...to a point. It has a much more satisfying chew to it than other species of mint, the leaves aren't as hairy and so don't give you as much of a "hairy tongue" feeling when you're eating it, but BOY does this plant ever pack a punch. Unfortunately, despite the leaves smelling like an orange grove in Florida or California, they don't taste a bit like what they smell. In fact, after chewing the leaves for a few seconds it's downright unpleasant.

Like most members of the mint genus, this plant has a dirty little secret. It has been used for centuries in a tea-like preparation as a medicinal beverage, and has been used to help everything from stomach aches and nausea to preventing or treating seizures. The pure extracted essential oils do show a lot of great medicinal potential for a variety of medical ailments (although not sold commercially for any disease, disorder, or symptom), but it's secret is that it is a potent carcinogen and mutagen. In fact, consumption of too much orangemint tea when pregnant will almost certainly lead to miscarriage. If it doesn't, there is a strong possibility for severe developmental deformities in the fetus (or embryo, depending on time of consumption during pregnancy). Because the compounds in orangemint extract are mutagenic, they cause DNA mutations which are irreversible. Always use extreme caution before consuming any "herbal" remedy during pregnancy. Just because it's "natural" doesn't mean it's safe!

Species name: Metha x piperita

Common name: menthol mint, peppermint

Location: teaching lab at Western

Next up we have the plant most commonly used to create the plant extract known as "menthol," peppermint. There are actually numerous species of Mentha that are used for this purpose, but the specific cultivar referred to as "menthol mint" is used most commonly because it has been bred to contain very high concentrations of this chemical. Peppermint is most probably native to Europe (there's the same problem as with orangemint for determining where exactly this species is native to based on the incredible amount of cultivation of this hybrid around the world), and is incredibly invasive in almost all areas it's planted.

One of the great things to note about many species of mint is that they are sterile hybrids. This means that the plant produces flowers, but these flowers don't have the ability to produce seeds. This is a great characteristic, especially in a potentially invasive species, because it means that the chance of this plant getting out of control can potentially be avoided. Unfortunately, there are two problems with this idea when it comes to peppermint: one, this hybrid isn't sterile (oops); and two, this plant produces below-ground biomass almost as quickly as it produces above-ground biomass. Peppermint plants produce huge numbers of rhizomes, which can grow underground and seek out new pockets of nutrient-rich soil to send up shoots to grow. This can cause the exponential growth seen in some areas, where for every one stem you pull out of the ground it seems like the plant sends up two more. Definitely a never-ending battle, and that mixed with the fact that it produces seeds that can blow away in the wind to create new plant colonies, means this plant is a very successful invasive species. Because of the fact that almost all species of Mentha have the potential to become invasive, you should never, EVER plant this directly in the ground, and especially not if you live near an environmentally significant or environmentally sensitive area.

Aside from the essential oil extraction, this plant is used for a remarkable number of uses. First, it is the most popular culinary additive in the world, especially in confections. In fact, there's recent evidence that its use goes back to 10,000 years ago in southeast Europe where it was found with other archaeological artifacts that suggest it was used to flavour food. It has also been used for medicinal purposes, as it is one of the most effective treatments for any kind of digestive issue from upset stomach to irritable bowel syndrome (IBS; there was a recent clinical trial that showed that the consumption of some amount, don't remember how much, of purified peppermint oil completely eliminated symptoms of IBS in 75% of women tested, and decreased IBS symptoms by at least 50% in all 15,000 women tested! That's incredible!). Now you know why restaurants give you an after-dinner mint! It decreases the feeling of being bloated, by encouraging the formation of small gas bubbles in your intestines. Might make you a bit gassy after a large meal, but I think that's better than laying on the couch groaning for an hour or two! Purified peppermint oil has also been used as a natural insecticide, as even in small quantities it prevents insect herbivory on most plants when applied as a spray. Purified menthol has been used as a medicinal additive for decades, most notably in muscle creams to give that minty smell but also a cooling sensation (which is why muscle rubs with a high concentration of menthol work incredibly well as methods of decreasing the itch associated with mosquito bites! The cooling sensation takes away the itch). Another good thing about peppermint oil is that it is one of the only members in the genus that does not display carcinogenic or mutagenic qualities, even in higher concentrations than one would ever be exposed to. In fact, peppermint tea is one of the most widely recommended "herbal remedies" for mild cases morning sickness.

Species name: Mentha spicata

Common name: spearmint

Location: teaching lab at Western

Spearmint is another incredibly commonly grown member of the mint genus, and like peppermint is incredibly invasive. It is not a hybrid so does produce viable seeds, but it also produces those same vigorous underground rhizomes like peppermint. Not a good combination! This species is native to Europe and southwest Asia, but is now grown commercially around the world. A very versatile plant, but one that should be treated very carefully; the flowers should be pinched off the plant before they're given time to set seed to prevent the spread of this species, and it should never, ever be planted directly in the ground.

Often with mint species (and other species used as herbs in the Lamiaceae like basil, rosemary, sage, and thyme), it is suggested that the flowers be pinched off before they're given much of a chance to develop. This actually has very little to do with the reproductive cycle of these species but rather with their use to humans. All plants display a phenomenon referred to the "allocation of resources" during all points of the plant life cycle, but this is more pronounced during flowering and fruiting. You'll notice perhaps with a lot of fruit trees that once the fruit starts to develop on the tree the leaves will turn and fall off at even the slightest change in climate without damage to the fruit. This actually has nothing to do with the health of the tree and everything to do with the attempt to give your offspring a healthy chance at being able to disperse and reproduce. Because (for example) a peach takes so much energy to produce a big, fleshy fruit around the seed, if the plant is under any kind of stress it will try to reduce the stress without impacting the next generation. This is why sometimes (especially nearing the end of the season) the leaves on the plant suffer. The same thing happens with highly fragrant plants once they start to produce seed. The seed producing takes much of the plant's resource allocation away from the production of secondary compounds (what gives the plant the smell), and instead puts all that energy into seed production. Great if you're a seed and want a good chance at being able to grow, but bad for you as a gardener if you want basil (or spearmint) with flavour! For this reason, make sure the flowers are pinched off the plant as soon as you see them start to develop. This will confuse the plant, and it will forget it was ever attempting to reproduce, ensuring that your leaves retain their potent flavour.

Like with peppermint (a hybrid created from spearmint), the essential oil of this plant shows very little mutagenic activity when tested. It is also effective medicinally against stomach ache, but so far hasn't shown much promise in the treatment of chronic digestive tract diseases or disorders. This is probably due to the fat that spearmint essential oil contains very little menthol and menthol-like derivatives. There has been the suggestion that spearmint oil can be an effective treatment for hirsutism in women, otherwise known as "excessive hairiness." Spearmint oil has anti-androgenic qualities, which means it can interfere with free testosterone in the blood. For those women that produce too much testosterone, this might be an effective treatment in reducing the amount circulating in the blood. Unfortunately, there are severe side effects associated with prolonged ingestion of concentrated amounts of spearmint oil such as kidney and liver failure. Until the dose-dependent and long-term effects can be minimized, this treatment won't ever make it on to the approved drug list in any country.

Species name: Mentha x villosa

Common name: mojito mint

Location: teaching lab at Western

Of course, we save the best for last. For those of you that have ever partaken in the consumption of the national drink of Cuba, you will likely have never had it made correctly :) Most places (or people) that make mojitos make it with regular old "mint," which is likely either peppermint or spearmint. This is all fine and dandy, but have you ever had one of those leaves or a piece of a leaf get sucked up in your straw and you have to make the decision to either eat it or spit it out? I bet you probably chose to spit it out, because of the "mouth feel" of the leaf. Both peppermint and spearmint leaves are very hairy, and give you a bad case of the "fuzzy tongue" if you consume a lot of it. True mojito mint, on the other hand, has leaves that are almost completely smooth which completely eliminates the fuzzy tongue feel. A great culinary advancement when it comes to tropical beverages!

This hybrid probably really did arise in the Caribbean, perhaps in Central or South America, and is referred to in Spanish as "yerba buena" or the "good herb" (this is especially true in Cuba). Many species of mint store at least some of their potent essential oils in glandular trichomes on their leaves, which is why they are aromatic just by lightly shaking the plant or touching the leaves. This is not the case in hairless varieties (or species), so the leaves must be treated carefully enough that you don't just get the "taste of plant" when you use them, but rough enough that you actually get the essential oils released from the leaf. This is done by muddling the leaves of the plant with sugar, sometimes alone depending on the species, to get the leaves to release their essential oils. When only using mint as a garnish and not in the drink itself, you always "spank" the mint to get it to release the essential oils.

Mojito mint is an example of a sterile hybrid, so this plant doesn't produce viable seeds (in fact, the plant rarely produces flowers which is also a benefit for those that want to use it for the fragrant leaves). It does still produce those vigorous rhizomes, so care does need to be taken when planting it. This is especially true in tropical and sub-tropical areas as it is drought tolerant, heat tolerant, and has a prolonged growing season which makes it a potentially successful invasive species. This hybrid is actually so vigorous and withstands harsh conditions so well that our plant actually came back after a cold Canadian winter!

Will this plant really repel mosquitos?

Species name: Cymbopogon citratus

Common name: lemon grass

Location: teaching lab at Western

Lemon grass (or lemongrass. Same thing) is native to southeast Asia, which should be intuitive for those that cook international cuisine (or local cuisine, I guess, if you're in Thailand or the Philippines!) since it is heavily used in Thai and Filipino dishes. If you've never seen the full plant before (as opposed to just the bulbous bottom of the stalk in the grocery store like in the third photo), you'll notice it looks a whole lot like ornamental grasses you might grow in your garden if you live in temperate North America, like zebra grass (which you can read all about HERE). This species of plant, while not in the same genus as zebra grass, is a close relative and in the grass family.

Like ginger (profiled a few days ago in a blog entry that you can read HERE), lemon grass has a ligule that is useful in identification of the species. It is a very unusual ligule in that there are long hair-like appendages that protrude out of the base of the blade of each leaf, and the papery part of the ligule is short and has nearly a straight edge (which is unusual for a ligule; usually they're longer in the middle than they are on either side and somewhat semi-circular shaped). It's a pretty characteristic ligule, and I'm ashamed to say I didn't get a great picture of it when I had the chance. I'll have to go track down this plant in the greenhouse and make sure I get a good picture of it! Like other grass plants, but unlike ginger, lemon grass has very non-descript flowers that are pollinated by the wind (and that is actually a photo of the flowers in the fourth photograph). This is a characteristic of nearly all species in the grass family, where the amount of resources necessary to allocate to a "pretty" flower used to attract insects or small animals (like hummingbirds or even mice) is far more than it is just to give way to the wind and rely on having your pollen blown from plant to plant. This is partly attributed to the habitat in which most grasses live; wind is abundant in prairie habitats and cheap to use. If you rely on living pollinators to cross-pollinate your flowers, you may run the risk one day of having pollen ready before there are pollinators around to transport it for you. Grasses have evolved "simplified" flowers to eliminate this risk and maximize the potential for pollination. Smart grasses!

As well as the great citrusy flavour lemon grass imparts on food and beverages, lemon grass has been used in folk medicine around the world for centuries. In Brazil it is believed to by an anxiolytic and hypnotic plant, but anyone who has ever had Thai food or lemon grass tea could probably speak to the lack of both of these effects, even when the plant is consumed in large quantities or consumed in a more concentrated form like chewing the stem. In fact, no scientific studies have ever substantiated this claim. Lab studies, however, have shown that this plant has the potential to show some medicinal value. It does show cytoprotective and antioxidant properties, suggesting that this may somehow one day play a role in cancer prevention (no known method of exploiting antioxidants to either prevent aging or prevent the development of age-related cancers currently exists, no matter what anyone tells you). One of the chemicals in the extracted essential oils of lemon grass has been suggested to play a role as an antihypertensive, and in lab studies the pure form, called citronellol, has been shown to lower blood pressure in mice and rats so there is definitely the potential to use this chemical as a potential blood pressure herbal medicine. There have been very few reports of this plant being toxic to any kind of domestic animal (human or non-human pets), so you don't have to worry much if you grow your own lemon grass. Cats anyway will stay away from it because it smells like citrus; unless you've got an atypical cat, cats hate any kind of citrus. Lemon grass oil has been reported to cause mild skin rashes in people with sensitive skin, so if you have extremely sensitive skin be careful handling the fresh-cut plant.

Sometimes extracts from this plant are referred to by the commercial name "citronella," which many of you will recognize as an insect repellant. So does it work? In my experience, no. There is no amount of citronella that you can burn or put on your skin that will truly deter the bugs you are determined to deter: mosquitos (and sometimes deer flies and horse flies). You can never truly "deter" a mosquito. They are out for blood (literally), and "smell" you via the carbon dioxide in concentrated forms that you exhale (which you can't prevent yourself from doing) and by the chemicals you exude in your sweat. Deet is the only chemical that can truly make you "invisible" to mosquitos by camouflaging your scent and throwing off the mosquito's radar. Deet does wear off incredibly quickly, so if you're in an area with a high density of mosquitos you can essentially be guaranteed to be bitten anyway (especially if it's hot and you're sweating, effectively both increasing your hormonal signal to the mosquitos and washing off the deet at the same time). Some people are naturally more alluring to mosquitos because they give off more of the mosquito signal chemical, and so they require more deet more often (I am, unfortunately, one of those people...). By rubbing citronella all over yourself, you're just making yourself smell more like lemons than you are like a human. This can work for about 30 seconds to deter mosquitos, but it is not going to work in the long term. Sorry for ruining your day if you use citronella oil as a bug repellant and have been wondering why you still get bit all this time :)

Does this mean citronella NEVER works against deterring bugs? No, it doesn't mean that. Remember that essential oils produced by plants are secondary compounds usually used in plant defence? Well, it smells like lemons for a reason. Citronella IS actually an effective insect repellant; clinical studies have shown that it is nearly 100% effective in deterring fruit flies from a specific area where it is applied, and it doesn't have to be applied in large quantities. It also does a pretty effective job of deterring stable flies, which bite not only humans but also horses and cows if they get a chance (and these bites are incredibly painful, bloody, and result in enormous welts on the skin). Citronella oil definitely does have a good use in insect deterrence, just don't expect it to do anything for mosquitos!

Three geraniums for your Sunday

Going along with the theme of "plants on display in the lab room of a course I TA," I have a series of three different, yet closely related, plants for this blog. The first one is a plant I've blogged about before, and the next two are unique (and I didn't even know they existed until I started with this course; now I'm trying to track them down to plant them in my garden somewhere!). The first image shows all of them together so you can get a bit of perspective about size difference and how they differ from each other on a "big picture" scale, then I'll profile each one of them separately.

This image gives away a bit of the surprise (hindsight: take the cardboard cheats out of the way before photographing next time!), but the major difference between these three species of geranium is how they smell. The one in the middle is the "ordinary" geranium, and the pots on each side are geraniums that each have unique smells that I force the students to identify (I'm awesome like that; I make my students use their senses in labs...I even make them taste plants! Don't worry, I ask about allergies at the very beginning so I don't kill anyone by accident). So let's get smelling!

Species name: Pelargonium x hortorum

Common name: common geranium

Location: teaching lab at Western

This first plant is probably the most easily identified species of any kind of geranium because they're so gosh darn common! Especially in North America, it seems like everyone, everywhere has planted at least one geranium plant in their garden in the spring (some climates in North America in the southern United States would provide ideal growth conditions to allow for the growth of geraniums all year; they are perennial plants in ideal conditions). The colour of flowers can differ drastically, as can the shape and general morphology of the leaves of the plant. The common geranium is native to southern Africa, where it is actually now nearly threatened in the wild because of habitat loss and the increasing frequency of severe drought. I have blogged about this plant twice before in two different forms; you can read all about the two cultivars HERE and HERE.

The easiest way to identify a "regular" geranium is by looking at the leaves (very fleshy and almost furry on both sides) and the flowers (the characteristic five petals with the stigma in the middle that's star-shaped; you might need to click on the image of the flower to make it larger to see it). Since other species of geraniums are less likely to flower both in general and in captivity (putting other species of geraniums in pots makes them significantly less likely to flower, but they do also have different flowering times so they might not have been "in season" at the time I took these photos), we'll concentrate on the leaves as methods of distinguishing these species.

Species name: Pelargonium crispum

Common name: lemon scented geranium

Location: teaching lab at Western

You can see right away that this species is quite different from the previous, "common" geranium in two ways. The first one is the way that the plant grows. Instead of it being a low, bushy plant, it instead grows thick, woody stems and the leaves are concentrated at the top of these stems. This is partly attributed to the general differences in growth habit of these species, but also a difference in breeding; the common geranium has been selectively bred over centuries to maintain a "low and bushy" growth form because it is more pleasing to gardeners. If you let the plant grow long enough indoors (or live in a climate where this species survives year-round), you'll notice it start to get taller and more wiry as it ages. Pruning can prevent this by keeping the plant short, but since the flowers only emerge from the top of the plant pruning is generally discouraged. It's much easier to just rip it out and replant it if you want to keep it short, or just learn to love a straggly geranium bush.

This species is also native to southern Africa, but is much more common in the wild because of its natural defence mechanism: the scented leaves. The plant hasn't just developed this ability to please humans; it has actually evolved as a way of deterring herbivores from eating the plant. The regular hairs on geranium leaves are called trichomes. The lemon scented geranium also has these trichomes on the leaves, but they also have specialized trichomes called glandular trichomes. These have a swelling at the tip of the hair that contains a tiny droplet of oil. When we separate the bulge from the rest of the hair we get this over-powering smell of lemon (the scent is very similar to Lemon Pledge, if you've ever used that for dusting then you'll recognize the smell immediately), but to a herbivore this means "STAY AWAY!" If a herbivore is silly enough to consume the leaf anyway, then they will in all likelihood be killed (if small) or learn to never do that ever again (if they're larger). The oil droplets contain potent chemicals that are toxic in large quantities; humans would have to ingest an entire plant in order to feel any ill effects so you don't have to worry about any accidental poisonings if you happen to own this plant (there is no reported toxic effects on cats and dogs, but you might want to play it safe and keep them away from it anyway). You will want to be careful, however, with this plant around very young children as the oil in the droplets can be very irritating to sensitive skin (and babies and young children generally have the most sensitive skin, especially on their hands, arms and face). As an aside (a relevant one): I have chewed on one of these leaves just to "try it out," and let me tell you. Not a pleasant experience. It doesn't taste AT ALL like it smells. Word to the wise.

The overall leaf shape of this species is also very different than a common geranium. The leaves are much more lobed than the common geranium, and there is a notch (or a "crisp," where the Latin name of this species comes from) at the end of every leaf vein. They are still fleshy like the common geranium, but another difference between them is that this leaf is much longer than it is wide, where the common geranium has almost a round leaf and at times even wider than it is long in some cultivars.

Species name: Pelargonium grassularioides

Common name: coconut scented geranium

Location: teaching lab at Western

The last plant we have as an example of the diversity of growth form in geranium plants is the coconut scented geranium. This species, also native to southern Africa, is much more common in the wild than the previous two, but not much is actually known about its current state of population abundance and successful reproduction. As it does share a native range with the previous two species, it can be assumed that this species would also be threatened by habitat loss but it can also tolerate much more harsh conditions than the previous two species; it can tolerate growing in really rocky conditions with little soil because of its vining growth habit.

To me, this species doesn't smell too much like coconut unless it's been well taken care of. It smells much more like "chemicals" (the best way I can describe it; it doesn't really smell like any kind of fruit or vegetable or nut). When the plant is happiest, it smells almost exactly like coconut-scented sunscreen (which doesn't actually smell all that much like coconut, but certainly smells like tropical beach!). This is a great example of the properties of secondary compounds, or compounds produced by the plant that are not necessary for survival and often play a role in plant defences. When a plant is under stress, instead of spending a lot of energy making chemicals that it can store in leaves to deter herbivores, it will instead spend all of that energy doing basic metabolic processes like creating sugars and repairing tissues. Once the plant is no longer under stress, it will go back to producing secondary compounds as long as it has the energy to do so. This is a great example of allocation of resources, where the plant almost "decides" where it's best to use energy and what energetically-taxing activities should be avoided. Like me on a vacation: laying by the pool doesn't take a lot of energy so should be done often, walking or running takes a lot of energy so should be avoided :)

The leaves of this species look very similar to the common geranium, but aside from the smell there are a few differences that you can look out for. The first is the texture of the leaf. Instead of being thick and fleshy, this leaf is much thinner and "normal-looking" (which can be seen in the lower photograph where there's a leaf I just happened to catch straight-on from the edge of the leaf). Also, the upper surface of these leaves are completely smooth, unlike the furry upper surface of the common geranium leaf (which may actually vary in hairiness, depending on the cultivar, but will always have at least some hair on the upper surface). The lower surface of this leaf is where all of the glandular trichomes are located. The leaves of this species are also unique in their coloration, regardless of the maturity of the leaf. When very young, the leaf will be much darker green around the leaf veins than anywhere else on the leaf. As the leaf ages (from the middle picture to the bottom one), it becomes much more uniformly green but if you look closely you can still see a bit of a difference in "green-ness" in some areas of the leaf. The last difference with the leaves is the margin or the edge of the leaf. This is a comparison that actually should be avoided, however, as the margins of the leaves of the common geranium can look drastically different based on cultivar.

One of the most easily observed differences between these two species is the growth habit. This species almost entirely lacks a stem; instead there is a dense mass of tissue near the soil level that acts as a stem, and the leaves emerge directly from the level of the soil. All of the above-ground mass is composed purely of leaves. As the plant wants to explore more territory to find more resources, it will create underground rhizomes that will seek out pockets of soil to establish a new basal stem mass to grow new leaves. This rhizome can traverse rock surfaces if needed, and where it is above-ground it will look nearly black because of all of the melanin (yep, the same chemical that your skin makes as a result of skin damage; we refer to this melanin production as "getting a tan") that is produced in the rhizome. This acts as a UV protectant, and can prevent damage to the rhizome as a result of exposure to the sun. Deeply pigmented plant tissues are also generally avoided by herbivores, as digesting melanin is a difficult process and may actually be a toxic process to some insects. I have also tried chewing a leaf of this species, and also not an overly pleasant experience. Gives a much more "fuzzy tongue" experience, so I'm guessing this would suggest it would be toxic in smaller quantities to humans. It would still involve the consumption of a LOT of the plant to produce any kind of ill effects, but best to keep this one more out of the way of children if you can. On the bright side, the essential oils produced by this plant are much less irritating to the skin!