1883.] The Achenial Hairs of Townsendia, 1103 
In Professor Asa Gray’s synopsis of the species of this difficult 
genus,’ the species are arranged in two sections, according to the 
size of the flower-heads and the more or less decided acumina- 
tion of the involucral bracts; and for sub-sections most use is 
made of the characters of the achenial hairs. In some of the 
species the hairs covering the fruit are described as acute or 1-2 
dentate, or again as 2—3 cleft or bracted; and ina large sub-sec- 
tion (including ten out of the seventeen species) the distinguish- 
ing character is “ achenial hairs glochidiate-capitellate, i. e., briefly 
bidentate at the apex, the teeth obtuse, recurved and sub-glandu- 
lar (?),” whilst an additional species of a preceding section is 
shown to have similar hairs. This peculiarity of the hairs is 
referred to in Torrey and Gray's Flora of North America as to 
T. sericea (“hairs minutely capitate ”), but not as to any of the 
other species. In Vol. vr of Wheeler’s Survey it seems to be in- 
dicated in the plate of Z. Rothrockii. 
In a former paper? I described and figured the curiously hooked 
hairs of the fruit of Z. grandiflora, and explained them as a spe- 
cial case of the duplex hairs which I had found to be characteris- 
tic of the Asteroidee and of most of the other tribes of the 
Composite. Professor Gray kindly suggested that I ought to 
extend my examination to all the species of Townsendia, and for 
this Purpose he generously furnished me with materials from the 
Harvard collections. I have also to acknowledge additional spe- 
cimens kindly furnished by Professor Vasey, of the Agricultural 
Department at Washington. sae 
My first step was to test the glabrous achenes of T. eximia, as 
Previous experience had shown that the glabrous species of gen- 
era belonging to what I may term the duplex tribes, themselves 
some duplex hairs, few in number or reduced in size, but 
Sufficient to establish their affinity. It was consequently no surprise 
to observe in the first shred examined from the achenial wall of 
L eximia, several stout duplex hairs (each .23™™ by 0.27 mm) with 
abruptly divaricating and slightly recurving tips, a decided case 
Athe glochidiate-capitellate ” pattern. These hairs are so 
parse as not to disturb the specific qualification of “glabrous 
achenes ;” but they justify its reference to this genus, notwith- 
Standing its chaffy pappus, and suggest that it (along with T. 
1 
„Proc. Amer. Acad. Arts and Sci., Vol. xvr, p. 82 (1880). 
On the Achenial Hairs of Composite, AMERICAN NATURALIST, Jan. 1883. 
