194 GREENE 



Head Lake, near Lake Okanogan, is every way true to the 

 type, except that the leaflets are less numerous ; nine in most of 

 the leaves and none with a greater number, a few having seven 

 only. In the same herbarium 4473, from Spence's Bridge, in 

 the same general region, has mostly 13 leaflets. The like is 

 true in the case of number 63749, collected at Cascade, B. C, 

 by Mr. J. M. Macoun in 1902. But all these specimens are in 

 one and the same unsatisfactory condition of early flowering, 

 with foliage, of course, not fully grown. They indicate, how- 

 ever, a northerly species, from which the two Washington spe- 

 cies herein characterized are sufficiently distinct. Not, however, 

 until mature foliage and fruiting panicles of it shall be brought 

 to light can R. occidentalis be properly described. 



26. RHUS ALBIDA, sp. nov. 



Probably low, the branches not robust, very light-colored 

 and, with the rachis and lower face of leaves, much whitened 

 with bloom, even the upper face of foliage of a pale color and 

 glaucescent : leaves 1.5-2.5 dm. long; leaflets about 13, not 

 crowded, not deflected but spreading, subsessile, 4-6 cm. long, 

 oval to oblong-lanceolate, abruptly acute or short-acuminate, 

 saliently serrate, the serratures 10-14 on each side : fruiting 

 panicle about 1 dm. high and quite broadly pyramidal, its 

 branches only very delicately but rather densely velvety : drupe- 

 lets much compressed and acutish. 



As far as known this very beautiful Rhus is local on the San 

 Francisco Mountain not far from Flagstaff in northern Arizona. 

 The type specimen, sheet No. 410696 of the National Her- 

 barium, was collected there, at an altitude of between 6000 and 

 7000 feet, August 18, 1901, by J. B. Leiberg, his distribution 

 No. 587 1. A perfect male flowering specimen is in my own 

 herbarium, as collected by myself at the same station, July 13, 

 1889. Again, National Herbarium sheet 334404 holds a flower- 

 ing branch from the same locality by D. T. MacDougal, his dis- 

 tribution No. 309, July 18, 1898. This, too, from an altitude 

 of about 7000 feet. The late date of its flowering, as an ally 

 of Rhus glabra in the generally torrid climate of Arizona, indi- 

 cates the subalpine character of its habitat. 



