Wednesday, October 15, 2008

Playing host

This summer, while combing through the vigorous, green plants of 120 vegetative monitoring plots in the Niangua Basin, my colleague let out a slow, low “uhhhh….huh.” Pointing to a blackened, desiccated flower stalk roughly 3 inches tall, he indicated he was, in short, stumped. Fire had ripped over most of the glade in early April leaving only small patches of grasses and wildflowers standing in the continually moist marly fens. The black stem was there among brown clumps of little bluestem and this year’s flowering loosestrife. We had both seen it on the glade before, but not very often. We knew what it was, but simply couldn’t remember it. Two days later, I called him at home and shouted “Buchnera americana!” into his cell phone. “Yes. Right. That’s it. Good,” he calmly uttered. And so our 2008 monitoring data was complete.

Blooming on Missouri’s glades and prairies from mid-June through October, blue hearts (B. americana) tend to grow in isolated populations, though I don’t know if this is diagnostic or just an anecdotal observation. After setting seed, their stems turn coal black. They thrive in fire-adapted landscapes, sharing ground with big bluestem, gentians, coneflowers and other glade and prairie plants. Blue hearts are hemiparasites, plants that receive at least some of their nutrition from a host plant but photosynthesize for survival, as well. A specialized root structure of parasitic plants, called the haustorium, allows the parasitic or hemiparasitic plant to feed off of other plants. In the case of B. americana, unfortunately, the fragile haustorium breaks easily, making determination of the host plant difficult at best.

Researchers in the 1930s discovered that blue hearts are generalist parasites, living on the roots of everything from sweetgum to Shumard oak. In fact, they lived on the roots of almost every bottomland hardwood forest tree species except cypress and pecan trees. However, I've never seen a blue hearts plant in a woodland or a forest, only on glades and prairies. For questions like this one: what is the host plant of Buchnera americana on a glade? I defer to an expert botanist, a talented, lovely man in St. Louis, who answered my question thus:

My impression is that the species does not show strong host specificity and will parasitize anything from grasses to woody hosts, similar to the situation in Castilleja arvensis.

He further added
This would be a good study for you to undertake in your spare time! You could do some excavations, but also you could harvest some seeds of Buchnera along with seeds of various plants from the immediate vicinity and grow the hosts in pots seeded with the parasite.

He's right. It would be a great study, very elucidating. I could find the plants, gather seeds of various surrounding grasses and herbs, even look for all of the species that cross over from glade to prairie. My loyal colleague suggested last week that goldenrods could be the host plant, known as they are from glades, woodlands and prairies alike; his mentor Julian Steyermark didn't even mention that blue hearts are parasitic. Oh, finding out the host plants of blue hearts would be a fun project. It's that "spare time" part that really confuses me. Where does a girl find that?

1 comment:

beetles in the bush said...

I wasn't aware of this plant - though I suspect I've seen it and stupidly assumed it was some kind of Phlox.

I once sent that lovely, talented man a photo of spring beauty in seed - asking him what sort of strange plant this was (hiding face)!

I'm glad there are such talented naturalists in the state whose footsteps I can follow.

all my best -- ted