Nelson: New Plants FRO>f Wyoming 247 



ranged : rays 50-60, wliite or barely pinkish : disk flowers very 

 numerous, all of them perfect. 



By separating the American forms from the Old World E. 

 uinfionis, Dr. Greene has simplified the study of the American 



species 



ipL 



As 



characterized by Dr. Greene, " Stem solitary, simple, involucre 

 densely villous-hirsute," the form now proposed as a species is ex- 

 cluded. E. vidanoccpJialus shows a constant tendency to a caespi- 

 tose habit and several stems : its dark, almost black, involucres are 

 strongly in contrast to the light colored ones of E. simplex. The 

 fact that the very numerous florets of the disk are all perfect seems 

 also to be in disagreement with E. simplex, as it is most frccjucntly 

 described. Both species occur in the Rockies but the latter has 

 the wider range and is, I believe, alpine while E. mdanoccphalus is 

 mostly alpestrine, occurring in the small, grassy parks below or 

 near the timber line. Undoubtedly many of the collections from 

 the Rockies belong to this species. Our numbers, 1772 and 

 5180 from the LaPlata IVIines, Medicine Bow Mountains well il- 



lustrate it. 



Erigeron Engelmanni 



Root single, short, tapering rapidly, woody, more or less 

 branched below : crown woody, from nearly simple to numerously 

 but very short branched : leaves very numerous, crowded on the 

 crowns, linear, on very slender petioles which about equal the 

 blade, closely sub-cinereous, somewhat ciliolate on the petioles, 

 from 2-6 cm. long (including the petioles): stems weak, decum- 

 bent or prostrate, moderately leafy, pubescence similar to that of 

 the leaves, 3-6 cm. long, monocephalous or with 2 or 3 heads : 

 peduncles short, ascending, i or morebracted: heads rather small, 

 involucre about 5 mm. high, its bracts equal, in two series, nar- 

 rowly linear, acuminate, dark green with light margins, ciliolate : 

 rays white, broadly linear, 40 (more or less), the ligules about 5 

 mm. long, equal : achcne small, obscurely pubescent. 



. In looking through the " inquircndi " sheet of Erigeron in 



Herb. Mo. Bot. Garden, I found just one specimen of this plant 



collected by Dr. Geo. E. Engelmann, June 26, 1880, at Ev^ans- 



ton, Wyo. My no. 5389, which I cite as type, is from the same 



locality, June 19, 1898, and is a perfect duplicate of luigelmann's. 



The habitat of this species seems to be the stony slopes of the 



foothills where each plant forms a flat, spreading mat among the 



stones. Its affinities, I should think, arc with E. Eatoni. 



