The most hated plant in North America

Today is a very special blog post, brought to you by one of my very best(est) friends, Tanya! Everyone say Hi to Tanya! (Hi Tanya!) Tanya gets to work outside all day every day (OK, not all day every day, but she gets to be outside A LOT with her job), and has some really awesome pictures of really unusual plants in North America. This one certainly isn't uncommon, but that doesn't make it any less special! This blog is her first (of hopefully many!) guest post for my blog, and she's writing about a plant most of us absolutely hate. And if you don't know if you hate it...do you get a runny nose and red, itchy eyes in the fall? Yes? Then you hate this plant. Trust me :)

Without further ramblings by yours truly, take it away Tanya!

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Species name: Ambrosia artemisiifolia

Common name: common ragweed, annual ragweed

Location: top image from our guest contributor; images 2, 3, and 5 from melody at Dave's Garden (available HERE); image 4 from htop at Dave's Garden (available HERE)

There may be another plant that a greater number of people despise (dandelions, maybe?), but for sheer intensity of feeling, I would argue that the most hated plant around must be Common Ragweed (Ambrosia artemisiifolia).  Every year in mid-August, many of us get that old, familiar itchy-eyes and runny-nose feeling that sends us running for filtered, air-conditioned air and antihistamines, and Common Ragweed is most likely the culprit.   

As Jen mentions in THIS POST, many people blame their fall allergies on showy flowering plants like the innocent goldenrods.  But, in order to cause your allergic reaction, you must breathe in the pollen grains, which means that the plant you’re allergic to is wind-pollinated: the plant produces lots and lots of pollen light enough to be blown around in the wind, and it’s betting that some of it will land on the female parts of another plant of the same species.  Plants that use this strategy have small, inconspicuous flowers because they don’t need to expend energy to attract pollinators like bees and butterflies to carry the pollen around for them.  Common Ragweed falls into this category: its pollen can be carried by the wind for hundreds of kilometers.  It’s hard to get away from this stuff.

Common Ragweed is native to North America (Jen says: I put "non-native" for the species status so that I could have a diagram with the "Invasive" box highlighted!) but has become an invasive species in Europe and Japan.  It is a “supertramp” species (yes, that’s a legitimate ecological term), which means that it produces lots of seed, disperses widely, and does really well in disturbed habitats. When you start looking for Common Ragweed, you’ll most likely find it in highly disturbed areas, like beside roads and in agricultural fields rather than stable forested areas, so really, it’s all our fault there’s so much of this stuff around: we’ve created lots of habitat for it!  There’s probably much more Common Ragweed around now than there was when Europeans arrived in North America.  You can burn it, pull it, mow it, or kill it with chemicals, but it will most likely come back in full force the very next year.  A good argument for increasing the amount of healthy forest and grassland habitats where Common Ragweed can’t compete, I say.

Ragweed leaves are compound and finely divided, and look a little like Wild Carrot (Daucus carota, which you can read all about in THIS POST) or Yarrow (Achillea millefolium, which you can read all about in THIS POST).  The flowers and seeds are produced in a tall spike called a raceme, and the plant grows to be about one meter in height.  This means that, in many areas, it isn’t completely covered by snow throughout the winter, and any of the seeds remaining on the plant remain accessible to animals like birds and small mammals.  The seeds have a very high oil content too, which makes them even more valuable to wildlife.  When Common Ragweed is causing you or your loved ones autumn misery, think about the mice and voles that will be depending on their stored ragweed seeds to survive until spring... and in the process, spreading them all over the place so there will be lots more for next year!

A speedy way to wellness

Species name: Veronica longiflora

Common name: long-leaved speedwell

Location: Ontario

This plant is a "nearly native" wildflower common in roadside ditches and disturbed open fields. Unfortunately, it is a poor competitor in southwestern Ontario so is rarely found in large abundance in natural habitats for long since it is out-competed by native and non-native goldenrods, thistles, and other asters like daisies (likely the non-native ones), black-eyed susans, and Queen Anne's lace. This plant is very attractive to bees and other insects, and are an important food source in Canada for the Grizzled Skipper, a butterfly that actually builds itself a shelter when still a caterpillar to use at night and when it's not feeding. Pretty smart caterpillar!

Like all good things in botanical nomenclature, the genus Veronica is being reanalyzed using DNA sequencing to determine relatedness between species. The morphological variation between species in the genus is quite drastic, as are the habitats of each species, and geographic location. Since there seem to be at least two distinct groups, one having its origins in North America and the other having its origins in Australasia, it wouldn't surprise me if genetically those were two distinct genera as well. It's actually estimated that the 500 or so species of Veronica might actually fit into as many as 7 other genera once analysis is complete.

Since so many people consider this plant species a "weed" (I personally think it's actually quite attractive...), there is one good thing about this plant existing in urban areas. The entire plant is edible! The leaves reportedly taste a lot like watercress, so a peppery spinach. The flowers are also edible, but just make sure there aren't any bugs hiding in them or else you might have a nasty surprise when you bite into your salad. The roots and leaves when dried have commonly been used in traditional North American medicine in a tea that is consumed to relieve chest congestion. If you are going to attempt to eat this plant, just make sure you're not confusing it with another common species that grows in the same type of environment, skullcap. Skullcap is in the mint family and has square stems, speedwell is in the snapdragon family and has round stems. As with all wild plants, if you aren't 100% sure of the identification of the plant, don't eat it!

The phytolace sewn by Queen Anne

Species name: Daucus carota

Common name: Queen Anne's lace, wild carrot

Location: Ontario

Queen Anne's lace is native to Europe and parts of northern Asia, although it is now considered naturalized in North America and an integral part of a prairie landscape. This doesn't, however, mean that it can't be invasive still; there are certain instances where it is a better competitor than native species and so the USDA has listed it as a noxious weed. The common name of this plant, Queen Anne's lace, is derived from the look of the flower: it is a type of inflorescence called a compound umbel, and at most stages of its development it looks like lace. The purpleish-red flower at the very centre of the inflorescence acts as a pollinator attractant, but is also said to be the drop of blood from where Queen Anne pricked her finger while making the lace.

The wild carrot has been domesticated into a subspecies of plant that we now use as the cultivated carrot. The genes that produce beta-carotene have been selected for over-production, so the cultivated carrot is orange compared to its white wild relative. The carrot is a biennial plant, which means it completes its life cycle over two growing seasons (in Canada, this would be two years since we have winter). The leaves appear the first year, photosynthesizing and making sugars to be stored in the taproot, the carrot, as starch. The plant then uses this stored starch to create a new shoot the next year which produces a flower and then seeds.

In agriculture, there are certain circumstances where this plant is actually a beneficial weed. The flowers attract wasp pollinators, which can benefit other plants surrounding it. When Queen Anne's lace is planted in tomato fields, the tomato yield increases over fields that don't have it. Not a bad idea for increasing yield chemical-free! There are some dangers to this plant, however. It has a wild relative that is also a look-alike called poison hemlock which can cause death to humans with consumption of only 6 or 7 leaves. The most famous victim of this poisoning is, of course, Socrates. Even without the poisonous plant confusion, wild carrot on its own can be harmful. The leaves contain chemicals which can cause severe light sensitive areas (burning, blistering, and extreme itching upon contact with sunlight) on the skin if you're especially sensitive to the chemical; if you're not as sensitive then it will just cause an itchy rash.

Medicinally, this plant was popular in the time of Hippocrates 2,000 years ago. He reported that this plant should be used as a contraceptive, and it was used for such a purpose for hundreds of years. The seeds were crushed, and the powdery substance was consumed. It was shown relatively recently that there are chemicals in the seeds of this species that do disrupt egg implantation, so I'm sure it would have been at least partially effective in the time of Hippocrates (and now). There is also some evidence to show it disrupts progesterone synthesis, which could also explain its potential effectiveness as a contraceptive. Very little mention is made of exactly how many seeds one would have to consume to get any noticeable effect.