Tom's Blog

Friday, August 15, 2008

Cream gentian now flowering

Cream gentian (Gentiana alba) is one of those great plants that we are now fortunate to have lots of at Pleasant Valley Conservancy. It is not common in Wisconsin and is State Threatened. It has a high Coefficient of Conservatism (7).

Originally, we had just a few plants lurking among the undergrowth in semi-wooded areas, but we had an alternate seed source and planted it widely. Where we now find it growing tells us quite a bit about its requirements. It has become very common in the savannas, and is also flourishing in the wet-mesic parts of the Valley Prairie.

It isn't a tall plant, and can be easily missed if you are just walking the trails, but with a careful eye you can see it in lots of places. The photos here are from the White Oak Savanna (Unit 12A) where it has been doing very well for the past four or five years.

In Wisconsin this species is found in scattered counties in the south and west, but according to Cochrane and Iltis, the abundance of known locations is deceptive, as this species has been over collected. The USDA distribution map shows it principally in the "prairie peninsula", with outliers in a few other states. It is considered endangered in Kentucky and Michigan, rare in Indiana, and extirpated (a gruesome term) in Pennsylvania.

There is a related species, bottle or closed gentian (Gentiana andrewsii), and in fact these two species are known to hybridize. We have this gentian also, introduced from a Wisconsin seed source. Although bottle gentian is generally blue or blueish, it also sometimes forms cream flowers which can be confused with those of cream gentian. However, the bottle gentian flowers remain closed at maturity, whereas cream gentian flowers open (as my photo here shows).

How do bottle gentian flowers get pollinated if the flowers remain closed? Actually, the bees have no trouble pushing there way into the flowers. In our flower garden I have watched a bee completely disappear inside a bottle gentian flower and then reappear with presumably a good load of nectar (and pollen).

Another gentian species that I wish we had is downy gentian (Gentiana puberulenta) which is a dry prairie species with stunning deep blue flowers. We have tried to grow this but the available seed source was defective. Our only other gentian at Pleasant Valley Conservancy, stiff gentian, although native to the property, is not very showy.


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