Monday, August 10, 2009

Nodding onion at peak in the savannas


Nodding onion (Allium cernuum) has become widespread at Pleasant Valley Conservancy in our savannas and is now at peak bloom. Although this species is also widely cultivated by gardeners, our populations have mostly spread on their own, as we have continued to control invasive shrubs in our savannas. It is also a prairie species, although most of our populations are in the savannas.

Although this species is widespread in the U.S., it is fairly restricted in its distribution in Wisconsin, just a few scattered counties, although our county (Dane) is one of them. According to Cochrane and Iltis (Atlas of Wisconsin Prairie and Savanna Plants), it is found primarily in dolomitic or other calcium-rich areas. This agrees with my observations; at Pleasant Valley Conservancy it flourishes on the ridge top savannas (Prairie du Chien Dolomite).

Yesterday while mowing our trails/fire breaks, I saw it all over, sometimes single plants, but more often large clusters. It is quite an attractive plant and should be easy to get established.

It has a Coefficient of Conservatism value of 7, a fairly high number.

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