Tom's Blog

Wednesday, July 8, 2009

Savanna grasses in bloom

This is the time of year when the savanna grasses are blooming. These are so-called cool-season grasses, which flower earlier in the year than the warm-season prairie grasses. We have four species of savanna grasses at Pleasant Valley Conservancy, three ryes and one brome. Two of the ryes are flowering now: bottle brush (Elymus hystrix) and silky rye (Elymus villosus).

Bottle brush grass is a distinctive grass that is dead easy to identify. It used to be classified in its own genus, Hystrix, when it was called H. patula, but after it was found to hybridize with Elymus virginicus its classification was changed.

We originally had only a few small patches in open areas along our ridge trail, where we collected seeds. After we began savanna restoration, we created lots more habitat, and planted this grass (and the other savanna grasses) widely. It thrived, and as we continued opening up areas, this grass moved in. Now we have it in all of our savanna areas and no longer need to plant it.

Although it does not burn as hot as the prairie grasses, it does contribute to a burn. I dug a few clumps and found last year's leaf bases present with charred areas from this year's burn.

We usually plant these savanna grasses in swaths rather than broadcast them, so that we find patches here and there in the savanna.

Along with many other cool-season grasses, bottle brush grass has a unique symbiotic relationship with an endophytic fungus that occurs intercellularly within the leaves and seeds. According to research by Keith Clay of Indiana University, the fungus symbiont enhances plant growth, reduces pest damage, and increases resistance to drought and other abiotic stresses. When the grass flowers, the fungus grows into the seeds and is hence transmitted to the next generation. Thus, the symbiont is transmitted from generation to generation via the maternal line, an interesting example of vertical transmission.


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