Monday, January 01, 2018

Fassett's Locoweed (Oxytropis campestris var. chartacea)

WI endangered, Federally threatened.

Photo 6/23/09. Western Bayfield County, WI
A story: Notice the secondary taxonomic ranking, a variety. Species within the Oxytropis campestris complex are found around the northern hemisphere. This variety is disjunct, that is, distant from other O. campestris varieties - the nearest variety is v. gracilis, some 340 miles to the west. At one time this was considered to be identical to v. johannensis, a variety found near James Bay and the Saint John River. However, genetic studies showed that the Fassett's locoweed samples descended from a common ancestor and the variety is a sister to v. johannensis. Thus, it was more isolated than some had thought. 
It exhibits high within-population diversity and low among-population differentiation. This leads to the notion that this species is a relict of a wider pre-Holocene distribution, possibly along the shores of large glacial lakes in the region. Glaciers receded, populations became isolated and differentiated.
Today, v. chartacea it is limited to the sandy, exposed, sunny shores of shallow, seepage lakes in WI. In times of high-water tables, when shores are submerged, the plant will be absent. Some may panic, thinking that it has been extirpated, or has become locally extinct. However, when periodic drought resumes and the exposed shoreline expands, the dormant seeds buried in the substrate, the seed bank, will sprout and the shoreline will be repopulated with the species. 
This was the case in 2009, as northern WI was in the midst of a 9-year drought and seepage lakes were shrinking dramatically. Although surveys a few years earlier during high water had revealed no Fassett's locoweed, and a grave sense of alarm was growing, the surveys in 2009 revealed approximately one gazillion specimens. 
Interestingly, the low water conditions exposed old corduroy logging roads that may have been constructed during the drought of the 1930's. 
Rain comes and rain goes.

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