Tuesday, November 26, 2013

Two species masquerading as Tauschia glauca?

Tauschia glauca is a serpentine endemic limited the California Floristic Province of far southwestern Oregon and northwestern California.    Two flower color forms are known: plants with yellow flowers occur in Jackson, Josephine and Del Norte counties.    Plants with purple flowers are more narrowly distributed, being restricted to Trinity County.

The purple flowered taxon was described as Velea glauca var. purpurascens J.T. Howell (Leaf. W. Bot. 2:185. 1939).  The purple-flowered taxon escaped the attention of Abrams (1951): then, there was only one California specimen, of the yellow flowered form (DS310004), at this disposal.   The purple-flowered taxon also escaped the attention of Munz (1959): again, he had access only to the yellow flowered taxon (RSA470298).  Jepson (1936) also did not treat Tauschia glauca as occurring in California, and in point of fact, his key to genera (p. 613) makes Velea yellow flowered!  The image below is my #21,353 from Gasquet, Del Norte County (Calphoto0000 0000 0813 2445 (2013-08-22)

This basionym has not been transferred to Tauschia, as it might well ought to be.

The protologue of Velea glauca var. purpurascens J.T. Howell, using a practice that remained acceptable at the time, designated types for both flowering and fruiting material.  Here, I consider the fruiting material, CAS255381, is considered as a syntype, and the flowering specimens are considered as the lectotype (lectotype CAS255378, isolectotypes CAS255379, NY406299, GH77821, POM251762).

The flower color of imaged specimens from Oregon specimens in flowering condition are all yellow (cf. SOC-VP-6465, REED-VP-3429, CIC-VP-40792, HPSU-VP-1130).    On Calphotos, the two posted yellow- flowered images [6249 3022 3948 0001 (1997-01-16) and  0000 0000 0813 2445 (2013-08-22)] are from Del Norte County.  By contrast, the Trinity County posted images [0000 0000 1211 0870 (2011-12-09) and  0000 0000 0711 1165 (2011-07-14)] are purple flowered.

The key uncertainty in my analysis is this: four specimens (shown on the map as red, three at: HSC38883. HSC49986 and HSC65900), are situated geographically intermediate between the centers of distribution of clearly yellow and clearly purple flower color forms.  What color might these be?   Might they be intermediate?  Might they be a third taxon?   The disposition of flower color forms in Tauschia glauca makes it necessary to go hither. 

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