126 PROCEEDINGS OF THE AMERICAN ACADEMY 



branched, wliite-tomentose becoming mostly glabrous and yellowish 

 green; bracts all small and deltoid i involucres shortly pedicellate or 

 subsessile toward the end of the branches, erect or spreading, tur- 

 binate-campanulate, a line long : perianth villous, the elliptical segments 

 yellow with greenish or reddish midveins, 1 to 1^ lines long. — In the 

 southwestern part of the Colorado desert, San Diego County, Cali- 

 fornia ; C. R, Orcutt, November, 1890 (n. 2189). 



P:RYTHR0N1UM, Linn. It is within the limits of the United 

 States that this genus reaches its fullest development. On this conti- 

 nent it is found scarcely beyond our own boundaries, and in the Old 

 World it shows a far narrower range of variation than here. Much 

 unavoidable uncertainty has long existed respecting the species of 

 western North America. Having taken advantage of such opportuni- 

 ties as presented themselves for studying these various forms, I now 

 propose, though with some hesitation, the following revision of the 

 genus. For material and for field-notes upon the ditficult western 

 species, tlianks are due especially to Mr. Carl Purdy, G. R. Kleeber^er, 

 and Volney Rattan, of California, Mrs. P. G. Barrett, Thomas Howell, 

 and W. C. Cusick, of Oregon, L. F. Henderson and W. N. Suksdorf, 

 of Washington, and Prof. John Macoun of the Canadian Geological 

 Survey. 



The eastern and western species are conveniently separated, as will 

 be seen, upon good distinctive characters. The Old World species, 

 considered as a unit, is most nearly allied to the eastern group in its 

 always solitary flowers, the want of a gibbous crest upon the petals, 

 and the shape of the capsule, while in its mode of underground prop- 

 agation it more resembles the western species. 



The characters that must be relied upon for the distinction of species 

 are rarely constant. The thinly coated corms produce new ones, either 

 as in the eastern species at base within the old coats or at the ex- 

 tremit}'^ of long oflHshoots, or as in nearly all the western species along 

 a rhizome, sometimes in near succession for several years, sometimes 

 at intervals of an inch or less. The habit of spreading by offshoots, 

 where it occurs at all, appears to depend much upon the season or lo- 

 cality, and is usually attended with a diminished production of flowers 

 and seeds. The form of the leaves is only exceptionally of any value. 

 In all the species the leaves in the cauline pair are unequal, one being 

 as a rule narrower and more acuminate than the other. The mottling 

 varies greatly in degree in the same species, or may even be wholly 

 wanting, and like the minute dotting, which is generally present, it 

 very often disappe irs in dried specimens. Only in J^. propullans do 



