Tuesday, June 9, 2009

Bindweed and Milkweed

A few weeks back I was in some Adams County, Ohio prairie barrens. These are fabulous habitats full of rare flora and fauna; always interesting observations at every turn. I was quite pleased to see the above in peak bloom. It is perhaps my favorite member of the Morning-glory Family (Convolvulaceae), the Erect Bindweed, Calystegia spithamaea. Don't be put off by the name, which combines "bind" and "weed" to conspire to create the image of some terrible mini Kudzu that wreaks havoc. This one certainly is not weedy, and is quite showy and diminutive in stature.

The flowers are stark bright white, and almost luminescent. Even the reproductive parts are white, but peer down into that corolla and you'll see a blush of yellow. When viewed head on, many morning-glory flowers seem to subtly glow from within, probably a ploy to attract the attention of pollinators.

The whole thing only stands eight inches tall, maybe, and the foliage surpasses the flower. This species occurs sparingly in dry barren openings, and in Ohio mostly in the eastern half of the state. Note the large leaf-like green bracts that cup the base of the flower. This separates bindweeds (Calystegia) from morning-glories (Ipomoea). The latter have much smaller bracts.

A real jawdropper, this one. One of thirteen species of true milkweeds in Ohio, Spider Milkweed, Asclepias viridis, may be the most bizarre. It is quite the rarity here, being confined to just five southern counties and mainly in the prairies of Adams County.

The identification is easy, as the flowers are massive - far larger than any of our other species.

Floral art in real life. The flowers almost defy description. And like all milkweeds, the blooms attract insects galore. While not much can eat milkweeds due to the toxic cardiac glycosides in the sticky white sap, bugs galore flock in to take advantage of the nectar. Note all of the tiny ants in these flowers, if you click on and enlarge the photo.



Heather said...

Wow, I dig that Spider Milkweed - love the color of the flowers! Looks like they're growing in some quite parched soil - is that their preferred habitat, or did you just happen to take the pictures during a dry spell?

nina at Nature Remains. said...

You're the one to asnwer this question that has been perplexing me for years (really!)
Is there some resemblance between convolvulaceae and milkweeds?
I always find more Monarch caterpillars munching away on the heart-shaped leaves strangling my vegetable garden, than the milkweed we leave standing in the field, just for that purpose.
What's up with that?!
No one else seems to have noticed this preference.

Jim McCormac said...

Hi Heather,

Yes, this is a milkweed of very arid lands. The barrns in which it grows are typically as parched as a tortoise in the desert.

Hi Nina,

I may have the answer to your mystery. I wonder if your "morning-glory" isn't actually Sandvine, Cynanchum laeve. This common plant is in the milkweed family, but is a clambering vine with leaves that look much like things in the morning-glory family. It contains the cardiac glycoside-filled sap as do other milkweeds; hence the monarch caterpillars' fondness for it.


nina at Nature Remains. said...

Thanks, Jim.
I'll check it out.
Would love to understand this better.