When a flower isn't a flower: part 2

Species name: Euphorbia pulcherrima

Common name: poinsettia

Location: Dominican Republic

The poinsettia, an incredibly popular ornamental plant as both a landscape plant in tropical locations and a potted plant in temperate locations, is native to Mexico and Central America. It is, contrary to popular belief in North America, a tree that can be up to four meters tall. A bit big to fit in a pot! Like many euphorbs, poinsettias do incredibly poorly in pots and shed their leaves quite quickly. This can be due to over- or under-watering, but usually is just a case of the plant being incredibly picky, and not being able to tolerate the short periods of sunlight that it does receive during our winters (8-10 hours of sunlight in a very sunny window versus the 12 hours of sunlight it would receive near the equator), and the temperatures that are much too cold (it prefers to grow at temperatures that average 25 degrees Celsius; much warmer than "room temperature" in the average house in North America during the winter!). This tree in the Dominican was significantly taller than I was, and while it was rather sparse on the green leaves it had enormous clusters of bright red flower bracts, or modified leaves.

Yes, that's right. Poinsettia "flowers" aren't real flowers. Sorry to disappoint you! The true flowers are illustrated in the bottom picture, and even at that they're not fully in bloom yet. The flower buds are the very small greenish pink knobs on the inside of the bracts, and will eventually open into either yellow or white flowers. They are incredibly inconspicuous even when fully open, and do not produce nectar and hence don't attract pollinators (even hummingbirds ignore the bright red bracts). The flowers are, instead, wind pollinated. The bracts also aren't always red, contrary to what we picture the typical Christmas poinsettia to be. They can also be orange, yellow, pink, white, green, and a mottled colouration, usually of pink and white together.

There is quite a bit of speculation about the toxicity of poinsettias, and parents who have "been there" are usually the first to warn you about how deadly this plant is. Well, let me tell you: all lies. Yes, if a small child ate one of the red bracts (or even a green leaf, or chewed on a stem) they would be quite ill with diarrhea and vomiting if they consume sufficient quantities, and learn never to do that again (albeit the hard way). In an analysis of over 26,000 supposed poinsettia poisonings, none resulted in death and only two required hospitalization (likely a hypersensitivity reaction). All were as a result of children and accidental ingestion. Some studies have looked at just how many leaves one would have to consume to die of the latex produced in the bracts, and the results are overwhelming: a 50 lb child would have to eat 500 bracts to require hospitalization due to risk of death from poisoning. That's a whole lot of poinsettia leaves, and I think the real question there if it ever happened would be how a child could get ahold of 500 bracts and be left alone long enough to consume them all. Sounds more like neglect than accidental poisoning! So will having a poinsettia around Christmas potentially kill a curious child? Absolutely not. You should still ALWAYS educate children about putting foreign plant parts in their mouth, because some houseplants are absolutely lethal enough to children to cause death upon consumption, just not this one. If they play with the bracts too much and release too much sap, the latex will cause skin irritation, rashes, itching, and in some children with hypersensitivity reactions to latex, hives. A word of caution: the jury is still out about this plant's toxicity to cats (it has the same reaction in dogs as it does in humans). There are an over-abundance of cases of cats dying as a result of eating poinsettia leaves, and perhaps some of them are true. But I have my doubts about the majority of them, considering how benign they are to humans (I'm guessing the cat probably got into something else that was in the house that led to the cat's death, but that's just speculation). Better to be safe than sorry; if you have a cat, make sure your poinsettia is out of reach to it (perhaps a tall order...literally) or you are vigilant while your cat is around the plant.

The association of the poinsettia to Christmas in the United States and Canada was merely a marketing ploy by a family in California, and a very successful one at that. The plants require a special grafting technique to merge two different species together in order to get the typical bushy plant that you see on store shelves in pots. If left to their own devices, poinsettia plants end up getting rather strange-looking and weedy, as demonstrated in the photos above. Once grafted, they look much more pleasing to the eye. But how to get those red bracts? Because those certainly are not "natural" when grown in North America...or is it? In Central America, because of the 12-hour days, all of the terminal branches have bright red bracts. In order to achieve this, the plants must be exposed to 12 hours of consecutive darkness for two consecutive months, with the other 12 hours being uninhibited sunlight. If any more or any less darkness reaches the leaves, they will stay green (or the plant will just plain old die) and the plant won't be all that attractive. This is the other reason why poinsettias never do well indoors in pots; rarely are they put in rooms that receive total darkness after sunset. I don't know about you, but I like turning on the lights in my living room after dark! The Ecke family business no longer produces poinsettias in California as they had since the early 1900s, but now produces them in the plant's native Mexico. They still serve 70% of the North American market for poinsettias around Christmas. In Mexico, however, this plant has special meaning. The flower bracts radiate outwards like a star, and is said to represent the Star of Bethlehem. Legend also has it that a young girl in the 1600s was too poor to provide a gift to Jesus on his birthday, and instead gathered weeds to lay outside the church. After a few days, poinsettias started to grow and the plants have been incorporated into Christmas celebrations ever since. While not a national plant, it is a very important culturally-significant plant in Mexico.

For part 1 of this blog, about the flower bracts of the bougainvillea, please read the blog post HERE.

When a flower isn't a flower: part 1

Species name: Bougainvillea spectabilis

Common name: bougainvillea, Napoleon, veranera, trinitaria (amongst others)

Location: Dominican Republic

Bougainvilleas are some of the most well known and well recognized tropical plants in the world. They originated from a relatively small band of South America, extending from Brazil west to Peru and south to Chile and Argentina. Depending on who you ask, there are between 4 and 18 species in the group (18 species is probably an over-estimation due to morphological variation displayed even in a single group of individuals, but I doubt there are only four species since diversity of plants in the tropics is so high). DNA sequence analysis definitely needs to be performed on this group to help not only with defining diversity, but also establishing if any of these populations (however isolated) are their own species and hence are in dire need of protection and conservation. One of the reasons why this is such a popular "resort plant" in tropical countries is because of its extreme ability to tolerate salt (it can tolerate being watered with seawater! That's salty!) it makes for an ideal ornamental species where salt spray (and periodic flooding due to storm surges) is common.

The "flowers" of the bougainvillea plant are great examples of how plants can entice animals into believing that they produce these large, showy flowers, but in reality produce small, barely noticeable flowers and fruit. The pink "petals" that many people believe to be the flowers aren't at all; they're just modified leaves containing pink pigments instead of green ones that act to attract pollinators (we call these bracts). The flowers themselves are the small white bits on the inside; there are usually three white flowers surrounded by three to six bracts. The bracts can be white, yellow, orange, red, pink, purple, green, or any colour inbetween. The only colour of bougainvillea bract that I don't think exists is blue; feel free to correct me if you've ever seen a blue one! There are over 300 different varieties of bougainvillea sold as ornamental plants, so it wouldn't surprise me if it had been "invented". Not only have there been hundreds of cultivars and varieties created through selective breeding, but bougainvilleas also naturally hybridize in the wild. There is even a population of plants in Peru, once thought to be a distinct species, that is a hybrid of two commonly found species. What's unusual about this hybrid population isn't the fact that it's a population of hybrid plants, it's where the parental plants are located. And that's nowhere near this hybrid population. There's no documented evidence, either, that either of the parent plants of this hybrid ever existed in this area of Peru. So how did they get there? Is this evidence of "early gardening" by native Peruvians? Is this evidence for population reduction in both parental species of bougainvillea? Can the seeds really be carried that far? Is there an animal vector (or was there an animal vector) that eats the fruit to disperse the seeds that we don't know about? Some fascinating questions with (so far) no conclusive answers.

Other than the ornamental value, this plant has no other uses to humans. The sap of the plant to some people is highly irritating to the skin; in people who are highly sensitive to the sap the reaction can be as extreme as it is to poison ivy. Other people either don't react at all or react with a slight rash and a mild itching. Luckily, unlike with poison ivy, a cut portion of the stem must come in prolonged contact with the skin in order to cause a reaction. This means that you should only be worried if you have been given the task of pruning a patch of bougainvilleas; if you have, make sure you wear a long-sleeved shirt and gloves and you'll be fine. This is also a very popular plant to turn into a bonsai (although, a different species is often used; B. glabra). The bougainvillea is the national plant of Guam, as well as the regional flowers of regions in China, Japan, Taiwan, Malaysia, Philippines, and the United States.

Stay tuned for part 2 of "When a flower isn't a flower" tomorrow, featuring one of the most commonly purchased plants for ornamental, indoor use.

If the spines don't get you, the latex will!

Species name: Euphorbia milii var. splendens

Common name: crown of thorns, Christ plant

Location: Dominican Republic

The crown of thorns is native to Madagascar, as are many species of Euphorbia. There are an estimated 100 species in the genus, but I have my doubts that they all belong. There seems to be a group of about 40 species that are native to Madagascar (some are critically endangered, some or more common but all are at risk due to habitat destruction), another group that are native to mainland Africa, and then yet another group that are native to Europe and South America (to see an example of the morphological variation in the family, read all about the chenille plant HERE). The plants native to Madagascar are very similar to the one pictured above; small-ish brightly-coloured flowers, very thick green leaves that are concentrated at the tips of the stems, long spines, and are relatively low to the ground. The ones native to Africa are trees; some can be up to 35 feet tall but otherwise similar to the Madagascar euphorbs. The plants native to Europe and South America are the weird ones; they're the round, "blobby" euphorbs that look absolutely nothing like their African "relatives". It wouldn't surprise me at all if there ended up being multiple genera within Euphorbia and a lot of renaming of species in the years to come. There are currently four sub-genera, but even those don't quite seem to be natural groups, at least to my untrained eye. I'm going to lay my bets on there actually being six genera within Euphorbia. We'll see if I'm right; I'll re-evaluate this blog if there's ever a genus-wide systematic DNA analysis that's performed.

The crown of thorns is a species that has a rather unique common name, due to its hypothesized role in Christian and Catholic beliefs. The story goes that when Christ was nailed to the cross, he was also forced to wear a crown made of a very thorny plant; whenever there's a painting depicting Christ's crucifixion, his head is always bleeding from the thorns digging into his forehead and scalp. It is believed based on geological evidence and stories passed down through generations (as well as artifacts discovered in Mosques and in underground burial tombs) that this plant was transported to the Middle East very early on; as many as 5,000 years ago. The story goes, then, that this plant is the source of the thorny branches that made up Christ's "thorn crown" during the crucifixion. The story of Br'er Rabbit, Br'er Fox and Br'er Bear courtesy of Disney also revolves around a dense thicket of thorns (I only know this because of the ride Splash Mountain at Walt Disney World in Florida...), and it's highly likely that these are some sort of euphorb (the story is based on folk tales told by African slaves after first being transported to the United States, so its doubtful the plants making up the Brier/Briar Patch would be American species) or other African spiny species.

All euphorbs are highly toxic. Some are more irritating only to the skin, while others produce noxious fumes from their latex (the white milky substance that is released when any part of the plant is damaged, as you can see in the third picture) and can cause severe respiratory problems. If ingested, this species won't kill you but will most definitely make you sick (vomiting, diarrhea and severe dehydration as a result of these two). African species can cause death just from contact with the latex, let alone ingestion. It's amazing the kinds of defence systems that some plants have evolved! Unsurprisingly, it is rare to find any kind of insect or other animal herbivore munching on these plants as a snack.

The flowers of this plant are quite neat, and you can actually gauge the age of the flower bracts by their colour. What we see as "flowers" aren't actually flowers at all. The two "petals" are modified leaves called bracts that contain chromoplasts instead of chloroplasts, which give the bracts their red to pinkish hue. These bracts change colour as they age, and the rate at which they change colour depends on the amount of sun they're exposed to and how long the bracts have been fully-developed. They usually start off a bright pink or red, then gradually fade to completely green before the fruit is mature, then the bracts fall off. Those small yellow patches on the very inside of the flowers are the true flowers; the fruit of these plants is rarely larger than a few millimetres across and is red when mature.

Botanical Chinese Lanterns

Species name: Abutilon megapotamicum

Common name: trailing abutilon, Chinese lanterns

Location: UWO Greenhouse

When I first saw this plant (unlabelled in the greenhouse) I thought "what a neat plant! They look like little Chinese lanterns. I'm going to call this the Chinese lantern plant!" Turns out I'm just as good at naming plants with common names as those who have come before me decades (even centuries) before; one of the common names of this plant is indeed the Chinese lantern plant! Contrary to what you might think from the name, it is not native to China, or anywhere in Asia for that matter. It is native to South America, in the tropical forests of Brazil, Uruguay and Argentina. I'm not sure of the status of this species in its native range, but if it's going through what every other plant native to the Amazon is going through it will be at risk of becoming threatened if the rate of deforestation doesn't drastically decrease.

The way that this plant flowers is completely backwards from what you would guess based on the images, and completely backwards from what I thought in my mind. I thought that I could blog about how the fruit of this species was especially cool because they have paper-thin walls, and the walls of the fruit either are shaken open in the wind when the fruit is mature or they are auto-digested in order to release the seeds. In fact, that red fruit-like structure is the immature flower before it has opened up. Those red "fruit walls" are actually sepals, the bract-like structures that cover the developing flower in order to protect it. What I thought was the spent flower, the picture at the bottom, that was turning into the fruit is actually the flower growing out of the protecting bracts and eventually it will unfurl and be a bright yellow-orange. The plant sure stumped me! I was thinking it was very closely related to the bladder cherry (also called the Chinese lantern plant), but they're not at all related and not used at all for the same reasons. The bladder cherry is sometimes used as an edible plant, but I've only ever heard of it being used as a decorative plant. In fact, one of the uses my supervisor told me about the lantern plant I'm sure you can do with this one, too: literally turn them into lanterns. During the summer when these are ready to bloom, go out and catch lightning bugs (or fireflies; whatever you called them when you were a kid!). Gently squeeze the sides of the red sepals until they start to split open at the bottom. Stuff some lightning bugs in, and voila! Glowing botanical lanterns. Just remember to let the bugs back out after you've taken some photos.

Whether a prawn or a shrimp, this kind isn't edible

Species name: Justicia brandegeeana

Common name: shrimp plant

Location: UWO Greenhouse

The shrimp plant, a pretty fitting name if you have bad eyesight and a good imagination (don't look much like a shrimp otherwise...), is native to Mexico and was introduced to Florida where it has become naturalized. The pinkish "petals" around the bottom of the flowers start off white, turning pink as they mature. The darker, more intense the colour the more light they were exposed to during maturation. These bracts continue to grow along the top of the inflorescence stalk until they become too much weight for the plant to bear and they break off. The more mature the plant, the longer the bracts can be; in some fully-mature plants they can be up to a foot long! Thats a big shrimp. The leaves also change colour in response to light; the chlorophyll is easily bleached out in high light levels. As the leaves are exposed to more and more direct sunlight, white spots start to appear on the leaves. To get rid of the spots, shade the plant. If you like the spots (it doesn't seem to hurt the plant much, although there will be an upper limit for the plant's tolerance), make sure it gets lots of sun during the day!

The shrimp plant is incredibly sensitive for frost; it would do very poorly in temperate climates if left outdoors during the winter (anything below 7 degrees Celsius and the plant will die) but they do perfectly well indoors. Outdoors during the summer they will attract butterflies and hummingbirds due to the long, trumpet-like shape of the flowers and the abundance of nectar that they produce. They will also attract a lot of ants and bees, so probably best to make sure it's not planted right beside the doorway to the house. You might regret your decision...

Another common name of the plant is the "false hop" plant, named after the bracts in some cultivars that are yellow or yellow-green. They mimic the bracts of the hops plant which are used to give the characteristic flavour to beer, but just to warn the home-brewers amongst you: the shrimp plant won't make your home-brew taste like beer, or even like shrimp. There aren't any reports of the plant being poisonous, but it's certainly not edible, either.

These flowers aren't for the dogs!

Species name: Cornus kousa

Common name: Chinese dogwood, Kousa dogwood, Korean dogwood, Japanese dogwood

Location: Ontario

Based on the common names of this species, it should be incredibly obvious where this plant is native: The Himalayan highlands of China, mountainous regions of Korea, and the mountains of Japan. The bright, showy flowers are produced in May and June, with the red fruits ripening into September. Despite having two of these trees in our yard, I have yet to see the fruit actually successfully grow into a new plant so I highly doubt it has any kind of invasive ability. That being said, there is a native species of this same genus that produces brilliant white flowers that could be planted instead. The downside of the native species (Cornus florida) is that it is very susceptible to a fungal disease called "anthracnose," and the Asian species is much more resistant to this disease. For this reason it is favoured amongst horticulturalists.

Despite appearances, those aren't actually flowers that appear in the photos above. The pink or yellow "petals" are actually bracts that surround the flower, not the flower itself. The flowers are rather inconspicuous and are located in the ball of plant tissue in the middle of the bracts. Each tiny flower in the inflorescence must be pollinated in order for that inflorescence to turn into a fruit. All of the maturing ovaries of the flower merge into one fruit, kind of like what happens in a pineapple. The fruits themselves are actually edible, and are sometimes used to produce the unique flavour of some fruit wines without adding too much sweetness.

There are quite a few references to dogwoods in popular culture, the most relevant (to this blog, at least) being that many farmers back in the "olden days" referred to cold snaps in the spring as "dogwood winters." The implication of this is that it's not safe to plant this year's crops until the dogwoods have started flowering, as flowering will be delayed in suboptimal conditions.