The series on narrow-range endemics of the Pacific Northwest of North America continues today. The first photograph in today’s entry is mine, while Keith Reher has kindly supplied the other two (thank you, Keith). Keith included the following comments:
“Attached are two images that I captured on June 1, 2008 near Peshastin, Washington. I have found Tweedy’s lewisia in Chelan County near Leavenworth and Peshastin, and I have read that an outlier population can be found in Manning Provincial Park, BC, but I have never been there during flowering season. Tweedy’s lewisias in Chelan County show a broad range of flower coloration, from the most common –yellow with pink tips — to pure white, pure yellow, and ivory with green central striping. The plant prefers exposed rocky soil or talus, but I have found them growing on shaded rock outcrops, deep in fir forests.”
My photograph is from an outlier population in Manning. Between Keith’s and my photographs, most of the entire distribution of Cistanthe tweedyi is covered — see the distribution map via the Flora of North America entry on Cistanthe tweedyi.
Many older references to this species will use the name Lewisia tweedyi, but a reclassification in 1990 moved this taxon out of Lewisia and into the genus Cistanthe. Will the name settle? Perhaps not quite yet; the Flora of North America states in its entry on Cistanthe: “The inclusion of Cistanthe tweedyi appears to be somewhat equivocal and it might best be treated as a distinct genus.”
Paghat has an excellent entry on Cistanthe tweedyi, though it is under the now-rejected Lewisia tweedyi. Note also that other common names are used: Pagaht uses Tweedy’s bitterroot while the USDA PLANTS database uses Tweedy’s pussypaws.