126 BOTANICAL GAZETTE [ AUGUST 
The lack of mechanical devices for distribution in these 
genera seems not to have restricted them, which makes apparent 
the often substantiated fact that certain inherent ground gaining 
tendencies apparently render distribution independent of mechan- 
ical contrivances. 
LOASACE. 
The Loasacee are almost exclusively a New World family, 
having, according to Gilg,? their center of distribution in Chili. 
The more extreme xerophytic genera spread thence over Argen- 
tine, and reaching North America find a second development 
chiefly in the Lower Sonoran zone. Four genera, Cevallia, 
Petalonyx, Eucnide, and Sympetaleia are endemic within this 
zone, Scyphanthus, Cajophora and Blumenbachia are southern 
extra-tropical. The largest genus, Loasa, furnishes many desert 
species for the Atacama and Argentine deserts, and while 
developed mostly in these regions and in the Andes, some 
species push north into Mexico (§ Saccate, 13 species, including 
L. triphylla, Peru to Mexico). But Mentzelia is the genus most 
conspicuous because of its distribution in the two zones under 
discussion, although quite abundantly distributed elsewhere, and 
particularly along the intervening Andes. 
Sec. I. TRACHYPHYTUM, eight species; two Chili, one Chili-Argentine, 
one Argentine, four western North America, of which M/. adbicaulis 
reaches the plains and gulf coast. 
Sec. II. MICROMENTZELIA, one species, M@. Zorreyi, in California and 
evada, 
Sec, III. EUMENTZELIA, twenty-six species. 
A, M. aspera, with the distribution of the genus; J. 0/#ge- 
sperma, North American, east to Florida; two Argentine 
species. 
Ba. One Atacama, one California, one Florida, two Texas and 
north Mexico. 
Bb Ia. Two Mexico, one Chili and Peru. 
Bb 18. Five Mexico, one Argentine. 
B bila. One Mexico. : 
BbIls. Two Mexico, one Bolivia, one Venezuela, one Colombia. 
9 Pflanzenfamilien 3%:106. The above account of the Loasacez is taken from 
this source. 
