Column: Milkweeds are neat

Published 12:32 am Thursday, July 6, 2006

By Staff
I don't really know why but I'm a big milkweed fan. Maybe it's because milkweeds are associated with prairies and butterflies, two of my passions. Maybe it's from my childhood days when I, like all rural kids, could entertain myself for hours casting the parachute-like seeds onto the winds. There's nothing trickier than landing a tiny parachute onto a designated downwind drop zone when the breezes are fickle. Great sport, that is.
Most of us are familiar with the common milkweed. Given a chance they'll grow most anywhere there's well drained soil. They're commonly seen in fallow fields and along roadsides. For some reason one of their favorite places seems to be in the grassy areas inside the circle type freeway exits and entrances. Probably because these areas are mowed enough to keep invading brush at bay but not so often as to discourage the milkweed. That's just one of the species, though. There is actually somewhere around a hundred species native to North America lumped into the milkweed family. I don't get that crazy with it, though. In my book, milkweeds have to be in the Asclepias (pronounced as-KLEEP-e-us) genus and have the general milkweed appearance to really be a milkweed. That narrows the field down to ten species known to grow here in Michigan. All are important nectar plants for butterflies, bees and hummingbirds.
By far the most prolific is the common milkweed. Less common but still frequently seen along roadsides is the showiest of the milkweeds, the butterfly weed. Swamp milkweed can be found with some regularity if you get into unsullied, high quality wetlands. It will even occasionally stretch the boundaries and grow in uplands adjacent to moist areas. From there, the rest of the milkweed species found in Michigan get pretty scarce and can be a real challenge to find. Several are even listed as threatened or endangered. Several years ago, there was a large patch of whorled milkweed, which is quite uncommon, along a highway south of Cassopolis, but two years ago it abruptly disappeared, undoubtedly succumbing to herbicide. Others, such as prairie, showy, blunt leaved and sullivant's milkweed are so rare you'd have to be lottery-winner lucky to find them. The other day Nate Fuller, a Southwest Michigan Land Conservancy naturalist, and I were out and about and thought we may have found a sullivant's milkweed, which is extremely rare in these parts. In studying the photos I took, though, I suspect it's a purple milkweed, which is also rare but not to the degree of the sullivant's. Not that I'm disappointed, I've been looking for purple milkweed for years to collect just a few seeds for my prairies.
Most milkweed blooms are clustered balls of tiny flowers. The majority of them are a somewhat dull, washed out pink color. Notable exceptions are the butterfly weed with brilliant orange flowers and the purple milkweed with bright reddish-purple flowers. Swamp milkweed flowers are also more on the order of purple milkweed. The tall-green milkweed's flowers are green but showier than it sounds. A couple species have white flowers.
Milkweeds are best known as host plants for monarch butterflies. It's the only plant monarch caterpillars eat. Most of the milkweed species are poisonous and the caterpillars retain this poison (with no ill effects), making them poisonous to predators. It's not enough to do serious harm to predators but it often makes birds barf. It certainly leaves enough impression for them to not try it again. This poison is also in the adult monarchs when they emerge. The toxin is poisonous to all animals, including humans. Since milkweed tastes so bad it's rarely an issue but can be a problem with cattle and sheep if too much milkweed is in the hay. Carpe diem.