December 29, 1914 
Vol. XXVII, pp. 221-224 
PROCEEDINGS 
()!•' THE 
BIOLOGICAL SOCIETY OF WASHINGTON 
THE GENUS CFIOISYA 
BY PAUL C. STANDI.EY 
(Published by permission of the Secretary of tlm Smithsonian Institution.) 
The genus Choisya is a member of the Rutaceae, whose species, 
hitherto considered to number only two,* are confined to Mex¬ 
ico and the southwestern United States. One of tliem, C. 
ternata, occurs in central and southern Mexico, while the other, 
C. dumosa, has included plants of local occurrence in the low 
arid mountain ranges of northeastern IMexico, extreme western 
Texas, southern New Mexico, and southeastern Arizona. 
The writer recently had occasion to determine a plant of this 
genus from the State of Coahuila, Mexico. It was obviously 
related to Choisya dumosa; but it came from a locality far 
removed from the previously known range of that species, and 
differentiating characters were at once apparent. Careful inspec¬ 
tion of the material in the U. S. National Herbarium under 
cover of C. dumosa soon convinced the writer that there were 
here represented three distinct types, besides the one from 
Coahuila. The four species of the dumosa group to be described 
have widely separated ranges, so far as known, there being 
some uncertainty as to the locality from which one of them 
comes. All except one are known from incomplete material, 
and it is to be hoped that, when flowers and fruit of all have 
been collected, additional distinguishing characters may he 
found. 
Key to the Species. 
Leaflets)), oblong to obovate, o-30 inni. broad. 1. C. ternata. 
leaflets linear, 1-4 mm. broad. 
Pubescence of the pedicels consisting of minute, appressed hairs. 
* Percy Wilson, N. Amer. FI. 25 : 205. 1911. 
44—Proc, fliOb. Sog, Wash., Vol. XXVIl, 1914. 
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