A STUDY OF RHUS GLABRA I9I 



on a side, upper face of a lightish green but somewhat polished, 

 the lower only pale, not whitened : fruiting panicle small, only 

 about 8 cm. high, definitely pyramidal, its branches short, 

 sparsely hirtellous : drupelets immature but perhaps full grown, 

 orbicular, or a little broader than high. 



At 6000 feet in the mountains near Provo, Utah, July 10, 

 1894, as collected by Mr. Marcus E. Jones, his No. 5612 as in 

 the National Herbarium. This differs from all other far-western 

 species in that its foliage is almost as highly polished as that of 

 R. copallina. 



21. RHUS TESSELLATA, sp. nov. 



Shrub low, copiously and densely leafy, the leaves rigidly 

 ascending, about 2.5 dm. long, the pinnae approximate; leaflets 

 about 15, lance-oblong, 5-7 cm. long, not quite sessile, cuspi- 

 dately acuminate, evenly and quite sharply serrate, the serra- 

 tures 13-17 on a side, the texture subcoriaceous even at flowering 

 time, upper face very smooth and somewhat shining, in general 

 dark green, showing very prominently the fine whitish midvein 

 and veinlets, but some intervals between veinlets wholly of a 

 light green, exhibiting the whole surface as notably checkered, 

 lower face merely pale and glaucescent, not glaucous : panicle 

 small for the foliage ; fruit not seen. 



Foothills of the Rocky Mountains in northern Colorado, at alti- 

 tudes of 6000 to 7000 feet; type specimen in U. S. Herbarium 

 No. 257466, collected by J. H. Cowen, July 20, 1895 ; no spe- 

 cial locality mentioned. The species by leaf characters alone 

 is a very good one, even if the checkering of dark and light 

 green be but accidental or occasional. The species here defined 

 may or may not include all the so-called R. glabra of eastern 

 Colorado mountains. 



22. RHUS MACROTHYRSA Goodding. 



Rhus macrothyrsa Good. Bot. Gaz. 37 : 56. 1904. 



Shrub 1.5-2.5 m. high, glabrous except as to vigorous young 

 growing shoots, these at base ferruginous-tomentose : leaves 

 2-2.5 dm. long; leaflets 9-15, green above, not glaucous be- 

 neath, oblong-lanceolate, sessile, acuminate, sharply serrate : 



