JOURNAL 
OF THE 
WASHINGTON ACADEMY OF SCIENCES 
Vou. 13 JUNE 4, 1923 | No. 11 
BOTANY.—Dissanthelium, an American genus of grasses. A. S. 
Hitcucock, Bureau of Plant Industry. 
The genus Dissanthelium is interesting because of the peculiar 
distribution of its three species and because of the confused nomen- 
clature of the original Peruvian species. 
Of the three species now referred to this genus, two are found in 
the Andes of Peru and Bolivia, one occurring also in Mexico, and a 
third is confined to islands off the southern coast of California. 
The genus was originally described by Trinius in 1836, based upon 
a single species, D. supinum, from Peru, “‘in frigidissimis ad Cerro de 
Pasco (America calidiore, Poeppig),’’ and is characterized by the two 
awnless florets, exceeded by the equal glumes. Cerro de Pasco is 
north of Lima. 
The California species is an annual (30 to 40 em. tall), with flat 
blades, growing at low altitudes. The other two species are dwarf 
alpine plants with narrow often folded or involute blades, D. calycinum 
being a cespitose perennial and D. minimum an annual. 
The type species of the genus was first described by Presl under 
Brizopyrum and was soon after transferred to Poa by Kunth, apparently 
without having seen the plant. The writer examined the type speci- 
men of Presl’s species at the herbarium of the German University in 
Prague and found that it was the same as the type of Trinius’s species, 
which he examined in the herbarium of the Academy of Sciences at 
St. Petersburg. On grounds of priority the older name must be 
adopted. The second Peruvian species was first given a name by 
Steudel without description and the plant was distributed by 
Hohenacker in his exsiccatae (Lechler, Plantae Peruvianae, no. 1836) 
as Vilfa macusaniensis Steud. Later Pilger described the same 
species as Dissanthelium minimum, basing it on Weberbauer’s no. 
5451 from Peru. 
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