160 



PITTONIA. 



would become the most striking of its characteristics when 

 contrasted, in the flowering state, with its western aiialngne; 

 for this is comparatively a rigid ungra.ceful clumpy bush 

 with dark roughish bark, few and ascenditig branches, and a 

 foliage which in its maturity is firm enough to be described as 

 subcoriaceous. In the Eocky Mountain form the leaves are 

 almost as broad as in C. Virginiana; hence, no doubt, the 

 confusion of these two in the herbaria : but in the original 

 C. demissa of the fartlier West there is a decidedly longer 

 and relatively narrower foliage, though its texture is less 

 firm, and more like that of the eastern shrub ; the branches 

 more elongated and divergent than in the bush of Colorado 

 and the Rocky Mountain plateau : moreover, this like Vir- 

 giniana sometimes approaches the form and dimensions of a 

 small tree. But the western aggregate is more inclined to be 

 pubescent ; and the foliage, when perfectly mature, is almost 

 white beneath, as if covered with a permanent bloom. Of this 

 whiteness there is nothing to be seen in my fruiting speci- 

 mens of a Virgmkina. It is also more pronounced and con- 

 spicuous in the Colorado shrub than in that of the Pacific 

 coast; indeed, I am not sure that its partial or total absence 

 trom the maturest foliage of true C. demissa may leave the 

 ^ocky Mountain form to take specific, or at least varietal rank. 

 J5ut this matter of lower surface color in the leaves, as well 

 as color and quality of drupes, form of putamen, etc., is much 

 la need of further investigation. Meanwhile, the constant 

 mfferences of habit and leaf-texture, will suffice to distinguish 

 the eastern from the western species, and to exclude C. Vir- 

 Uimana from the Rocky Mountain flora. It would, however, be 

 ^ery interesting to know how far eastward in Dakota, Nebraska 

 or perhaps Minnesota, the Rocky Mountain Choke-Cherry 

 perchance may run. 



/< 



^EUASUS EMARGINATA, Dougl. in Hook, Vl i. 169. C CaU- 



> mm Greene, PL Fr. 50 ; Gard. & Forest, iy. 243. Since 

 tue initial pages of the Flora Franciscana Avere published, 



