68 BOTANICAL GAZETTE [JANUARY 
A. Gray, Syn. Fl. 2:263. 1878, not P. secundiflorus Benth.” 
Inasmuch as GRAY wrote his description from a specimen or speci- 
mens deposited in the Gray Herbarium, one of these collections 
must logically be taken as the type of P. unilateralis, and not a 
specimen arbitrarily set up as such in another institution. But to 
return to the question of the relationship of these species. In the 
first place, the status of P. wnilateralis seems to depend primarily 
upon the value of the presence or absence of hair on the sterile 
stamen as a specific character. Most recent authors, including 
RypBERG in his Flora of Colorado (306. 1906), have relied upon this 
character as a means of separating groups of species, and ordinarily 
it is doubtless of value, especially when accompanied by other 
characters, including distribution. Now according to RyDBERG’S 
key (Fl. Colo.), P. secundiflorus Gray and, in fact, P. secundi- 
florus Benth. (see DC. Prod. 10:325. 1846), have the sterile 
stamen bearded at the tip,.while in P. wnilateralis Rydb. it is 
glabrous. But in P. perpulcher A. Nels. the sterile stamen is 
always bearded, yet RypBERG would reduce the latter to his 
species. Obviously the reduction of P. perpulcher means the 
reduction of P. unilateralis, and indeed it is very doubtful whether 
the latter is specifically distinct from true P. secundiflorus, as 
the two forms grow in the same localities in Colorado and seem 
to possess no constant difference unless the sterile stamen character 
is reliable. But the case is much stronger for P. perpulcher. Both 
the other species are glabrous, the corollas average a good 2 cm. in 
length, and the plants range from Wyoming to northern New 
Mexico. P. perpulcher has only been collected in northwestern 
Idaho, but is frequent throughout that part of the state. Its 
foliage is decidedly puberulent and the corollas generally run less 
than 2 cm. in length. The puberulence is suggestive of P. virgatus 
Gray of New Mexico and Arizona, and in spite of the narrow leaves 
and glabrous sterile stamen of that species P. perpulcher is probably 
more nearly allied to it than to the Colorado species. 
n Bor. Gaz. 55:382. 1913 we proposed var. pandus to take 
care of a plant in which the puberulence extends throughout. We 
did not notice, however, that the sterile stamen is glabrous. Alto- 
gether this plant seems to be related rather to P. virgatus, although 
