374 RYDBERG: SOME SENECIOID GENERA—I 
many, in a leafy panicle; involucre campanulate-turbinate, 12- 
13 mm. high, about Io mm. broad, subtended by I-3 narrowly 
linear leaves, scarcely longer than the bracts; bracts about 8, 
lance-linear, acute, hispidulous on the back; flowers 10-12; 
corolla-tube 7 mm. long; throat 0.5 mm. long; lobes nearly 5 mm. 
ong; achenes glabrous; pappus 7 mm. long. 
Type collected at San Luis Potosi, 1879, Schaffner 725 (herb. 
N. Y. Bot. Gard.). 
P. argutum is closely related to P. peliatum differing in the 
outline and cut of the leaves. 
SAN Luts Potosi: Schaffner 725; Parry & Palmer 543. 
DuRANGO: E. W. Nelson 4954. 
7. Psacalium megaphyllum (Rob. & Greenm.) Rydb. 
Cacalia megaphylla Rob. & Greenm., Am. Jour. Sci. III. 50: 
157. 
This is related to the two preceding, differing in the smaller 
5-6-flowered heads and usually only 5 bracts. The type came 
from Guadalajara, Jalisco. 
JALisco: Pringle 2490. 
MorELos: Pringle 6165. 
MIcCHOACAN: Arséne 2386. 
PUEBLA: Nicolas 334; Arséne (in 1908). 
8. Psacalium obtusilobum (Rob. & Greenm.) Rydb. 
Cacalia obtusiloba Rob. & Greenm. Am. Jour. Sci. III. 50: 
< 
It differs from the last in the round-lobed basal leaves and 
the smaller involucre. It is known only from the type collection 
from Sierra de San Filipe, Oaxaca, Pringle 5840. 
9. Psacalium peltigerum (Rob. & Seaton) Rydb. 
Cacalia peltigera Rob. & Seaton, Proc. Am. Acad. 28: 111. 1893. 
This is characterized by its deeply divided leaf-blades, the 
divisions again divided into lanceolate or lance-linear lobes; 
the bracts are 5 or 6, glabrous, and the flowers 5-7. Type 
locality, Rio Blanco, Jalisco. 
JaLisco: Pringle 9872, 4627, 5154; Palmer 171. 
10. Psacalium Nelsonii Rydberg sp. nov. 
Ste h or more, sulcate, tomentulose-puberulent; 
basal leaves long- petioled ; pinta about 3 dm. broad, cleft 
