244 PITTONIA. 
2. L. sP1Nosa. Aster? spinosus, Benth. Pl. Hartw. 20 
(1839); Gray, in T. & G. Fl. ii. 165 (1841). Aster spinosus, 
Gray, Pl. Lindh. ii. 219 (1850), and Syn. Fl. 208. Notwith- 
standing the great elasticity of the genus Aster as main- 
tained by Bentham and by Asa Gray, both these authors 
early held this plant to be only a very dubious Aster. But 
it was never, like the type-species of Leucosyris, shifted about 
from genus to genus on trial. The two species go well to- 
gether, being at agreement in having pale green reedy al- 
most leafless stems, and permanently white corollas, the 
rays being either very short or wanting. 
The typical L. spinosa is Mexican and Central American, 
and is described as shrubby or at least suffrutescent; and 
the same character is attributed by Lindheimer to the Texan 
plant. This leads me to doubt if the plant of the lower 
Colorado and Gila rivers be not a distinct species. I have 
seen many acres of this, both in Arizona and California, 
and am certain that there it is at least ordinarily a herba- 
ceous perennial, the numerous annual stems arising from 
horizontal roots or rootstocks, and when young are clothed 
with long linear flaccid leaves; these mostly disappearing 
before the flowering season; and some specimens pass to 
the flowering and fruiting without developing any spines. 
It is, in fact, never the manifestly shrubby and forbiddingly 
spiny bush which comes to us from towards Central Amer- 
ica under the name of Aster spinosus. 
To the genus Leucelene, proposed at page 147 preceding, 
I tentatively referred Nuttall’s Chrysopsis alpina when fin- 
ishing the manuscript of the Composite for the Flora Fran- 
ciscana ; but such a disposal of that interesting plant of the 
northern Rocky Mountains does not satisfy. Leucelene, a8 
based on the small branching herbs of the Rocky Mountain 
plains and hillsides, will doubtless be shown a genus | 
several species at one in habit as well as character; mean- : 
