No. 5.— Contributions from the Gray Herbarium of Harvard 
University. New Series. — No. 17. 
By B. L. Robinson and J. M. Greenman, Cambridge, Mass. 
1. REVISION OF THE GENUS GYMNOLOMIA. 
The genus Gymnolomia, so far as known, is exclusively Ameri¬ 
can and extends from the northwestern parts of the United States 
to Brazil. More than half its species, however, are confined to 
Mexico and Central America. The genus in its present circum¬ 
scription has never been monographed. Kunth when founding it 
in 1820 described 4 sjDecies. De Candolle in the Prodromus, 5, 561 
(1836) changes rather arbitrarily Gymnolomia to Gymnopsis under 
which 10 species are described of which several have since 
been referred to other genera. In 1873, Bentham and Hooker f. 
ascribe to the genus Gymnolomia 16 species. Baillon in his His- 
toire des plantes regards the genus Gymnolomia as of doubtful 
value. Hoffmann in Engler and Prantl’s Nat. Pflanzenfamilien 
maintains the genus and ascribes to it 20 species. Aside from the 
brief citations of the Index Kewensis by far the best bibliographic 
enumeration of the Gymnolomias is that of Hemsley (Biol. Cent.- 
Amer. Bot., 2, 161) who cites literature and stations for 15 species, 
found in Mexico and Central America. 
The present revision, including 37 recognized species and several 
varieties, has been chiefly based upon the specimens in the Gray 
herbarium, now largely supplemented by the incorporation of the 
Klatt herbarium. But through the kindness of Mr. Coville and 
Dr. Rose, the representation of the genus in the U. S. national 
museum has also been examined with profit. 
The revision of the genus has presented three chief difficulties, 
vi Z- : — 1. The distinction of our own western and southwestern 
forms, which have, notwithstanding great diversity of foliage, pu¬ 
bescence, size of heads, and duration, been loosely grouped under 
G. multiflora. 2. The exact interpretation of the Central Ameri¬ 
can G. subflexuosa , Benth., upon which must depend the varietal 
and specific nomenclature of some of the nearly related species. 
3. The explanation and proper treatment of several large-headed 
