CONTRIBUTIONS FROM THE ROCKY MOUNTAIN 



HERBARIUM. III. 



A V E N Nelson. 



STUDIES IN ERIOGONUM. 



This genus is remarkably well represented in Wyoming. 

 Since most of the species in it are peculiar to arid America, any 

 of the states with desert areas may be expected to represent a 

 considerable number of the increasingly long list of species. A 

 line drawn from central Wyoming to western Arizona will divide 

 into somewhat equal parts the Eriogonum belt. 



No recent revision of the genus has been published, but a 

 considerable number of new species have appeared. When one 

 considers how extensively collections have been made in the 

 and west indicated above, it seems rather remarkable that Dr. 

 Watson's revision of twenty-five years ago (Proc. Am. Acad. 

 ^2 -^54) should so nearly represent our knowledge of these 

 plants as it does. That a revision is now needed I think all will 

 admit, but until some one finds time and occasion to do so, notes 

 upon and additions to the species may not be out of place. 



Eriogonum orendense, n. sp. — Caudex woody, almost wholly 

 subterranean, its numerous branches densely tufted : tomentum 

 rather dense, uniform throughout the plant, giving it a greenish- 

 vviiite hue : stems numerous, crowded, very short, exclusive of 

 the woody persistent base not to exceed S"""^ • leaves numerous, 

 crowded, narrowly oblong or oblanceolate, subacute, 1-3 ^"^ long, 

 tapermg into a slender petiole which usually exceeds the blade : 

 scapes erect, 7-^1 5 ^m lon^, surpassing the leaves : inflores- 



cence umbellate, with short subulate bracts ; the rays unequal, 

 1-2^"^ long, terminating in a few^flowered cyme (3-7)^ with very 



short connate bractlets : involucres short-peduncled 

 turbinate, merely toothed around the summit, about 3""^ long, 

 niany.flowered (8-12): calyx bright yellow; the segments 



1902] 



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