48 PITTONIA. 
5. X. TORTIFOLIA. Aplopappus tortifolius, Torr. & Gray, - 
Jour. Bost. Soe. v. 109 (1845). Aster tortifolius, Gray, Proc. — 
Am. Acad. vii. 353 (1868). A. Mohavensis, Coville, Death 1 
Valley Exp. 126 (1893).—Along the Colorado River in Utah — 
and Arizona, westward to middle California in the vicinity | 
of the Mohave Desert. 
6. X. FRUTESCENS. Aster frutescens, S. Wats., Proc. Am 
Acad. xxiv. 55 (1889).—Northern Lower California ; strictly 
congeneric with the last, though with heads much smaller, - 
and foliage reticulate-venulose. : 
X. OnouTTH. Aster Orcuttii, Rose, Bot. Gaz. xvi. 118 
t. H (1891).—Of the Colorado Desert, in the southern part . 
of California; in aspect too unlike any of the preceding, 
and more soiifmed to that of certain species of Hazardia 
by its leafiness and short-peduncled heads; but in char 
acters of flower and fruit it is a Xylorrhiza. Mr. Rose ha 
shown himself a careful observer by noticing the white bark 
of all the stems and branches. It, however, characterizes 
every species of this genus, though I believe no one in de- 
scribing any of the others made any mention of it. 
should enter into the description of the genus as a marked 
vegetative character. 
pi 
- It sometimes happens that a botanist's first impression 0 
the affinities of some new plant are nearer the truth tha 
the different conclusions which he may have reached under 
the guidance of the conventional eriteria of affinity; 
metbod largely empirical, and its results often unsatisfactory. — 
The case of the plant which Asa Gray, after he had given it 
analytic study, named Aster eryngiifolius, I take to be illus- 
trative of this; for, in my view, his earlier judgment that i 
was a species of Prionopsis, though not quite correct, was 
more philosophical, and came nearer the truth. 
In its whole aspect this plant is most unlike anythin 
