& 
STUDIES IN THE COMPOSITA. 265 
List! as applying to North American plants, is precluded. 
I therefore here assign this group the name 
TETRANEURIS. 
Of this genus, very easily recognizable by habital peculiar- 
ities, the essential characters are (1) an involucre of thin 
soft herbaceous bracts all distinct, and, though biserial, all 
alike; (2) a merely low-conical receptacle; (3) quadrate rays 
not dilated at the 3-toothed summit, and marked by just 
four parallel simple nerves (whence the name); (4) very 
broad anther-tips, as broad as long. 
Of this I recognize the following species : 
* Peduncles scapiform and leafless. 
1. T. acautis. Galardia acaulis, Pursh, Fl. ii. 743 (1814). 
Actinella acaulis, Nutt. Gen. ii. 173 (1818). Cephalophora 
acaulis, DO. Prodr. v. 663 (1836). Ptilepida acaulis, Britton, 
Mem. Torr. Club, v..339 (1894). Tufted and almost sublig- 
neous perennial of bleak hills, with silvery-silky foliage, 
frequent along the Rocky Mountains from New Mexico to 
Assiniboia. 
2. T. Torreyana. Actinella Torreyana, Nutt. Trans. Am. 
Phil. Soe. vii. 379 (1841). A. glabra, A. Nelson. Fl. Wyom. 
137, not of Nuttall. Certainly one of the best of species by 
its almost glabrous strongly punctate foliage, and scarious- 
margined bracts of the involucre, awnless pappus, ete. No 
one has yet noticed that in this species alone the flowers 
ave a greenish-yellow shade. 
3. T. LANATA. Actinella lanata, Nutt. 1. c. Comparable 
With the last, but very dwarf and woolly, especially as to 
Scape and involuere, the bracts of the latter scarious-mar- 
Eined ; the leaves also very woolly when young, but in age 
dn 1 Mem. Torr. Club, v. 339. 
