Polemonium chartaceum (CHSC3180) at Donner Pass
I hereby record that I did not relocate a Polemonium at Crater Lake, on
the western flank of Boreal Ridge, Nevada County (ca. 7500 feet
elevation), visited on Friday last. The terse label on the
specimen suggests that it was gathered on an ascent to the lake from Norden, to
the south. I obtained Crater Lake by
driving to the summit of Boreal Ridge, thence to the lake and vicinity from the
ridge proper.
The immediate vicinity of the Crater Lake is an odd geologic setting in
that the andesite (?) locally forms blocky (ca. 2 dm average diameter) patches
largely barren of vegetation – not unlike typical habitat for the tufted-alpine
polemoniums (Grant 1989)
The record CHSC3180 filed as Polemonium eximium is worthy of more study.
First, the elevation of this record is an
extreme low-elevation outlier, being located several thousand feet in elevation
below the lowest known records for Polemonium eximium, which as you know is one
of the highest-elevation limit vascular plants in the Sierra Nevada alpine.
Secondly Polemonium CHSC3180 has the membranous/chartaceous leaf bases
which characterize P. chartaceum and its sister taxon P. eddyense, which are poorly developed in P. exemium
Third, the geographic location is essentially distant from either
taxon, in being removed ca. 130 km from
the population of P. chartaceum (proximal in the Sweetwater Mountains, Mono
County), or, 300 km from P. eddyense on Mt Eddy, largely on the Siskyou County
side, in far northwestern California.
An ascent and search from Norden is suggested. My working hypothesis is that CHSC3180 is the
sole collection of an undescribed taxon in the P. chartaceum-P. eddyense clade,
geographically and mid-Pleistocene era isolated from its congeners.
Grant, Verne. 1989. Taxonomy of
the Tufted Alpine and Subalpine Polemoniums (Polemoniaceae). Botanical Gazette Vol. 150, No. 2, pp. 158-169
No comments:
Post a Comment