HITCHCOCK AND CHASE—NORTH AMERICAN PANICUM. 231 
135. Panicum thermale Boland. 
Panicum thermale Boland. Proc. Calif. Acad. 2: 181. 1862. ‘‘On hot rocks and 
in hot water flowing from the Geyser springs and Geyser mountains, in the northern 
part of Sonoma County,” California, The type, in the Gray Herbarium, is the early 
branching form. It is marked ‘‘I call this: Panicum thermale till I shall know 
better. It grows in the Geysers Sonoma Co. and on hot rocks,”’ 
DESCRIPTION. 
Vernal culms grayish green, densely tufted, velvety-villous, 10 to 30 em. high, 
ascending or spreading, the nodes with a dense ring of short hairs; sheaths often over- 
lapping, velvety-villous; ligules 3 mm. long; blades thick, ascending or spreading, 
3 to 8 cm. (mostly about 5 cm.) long, 5 to 12 mm. wide, acuminate, rounded or sub- 
cordate at base, both surfaces densely velvety-villous; panicles exserted or in high 
alpine specimens partly included, 3 to 6 cm. long, about as wide, densely flowered, 
the axis villous, the flexuous branches spreading, often drooping; spikelets 1.9 to 2 
mm. long, | mm. wide, obovate-oblong, obtuse, 
turgid, papillose-pilose; first glume about one- 
third the length of the spikelet, obtuse or abruptly 
pointed; second glume and sterile lemma sub- 
equal, the glume shorter than the fruit at ma- 
turity; fruit 1.7 mm. long, 1 mm. wide, elliptic, 
subobtuse. 
Autumnal form widely spreading, the branches 
appearing even before the primary panicles are 
exserted, repeatedly branching, the whole form- 
ing a dense cushion, the blades and panicles of the ultimate branchlets reduced; 
winter rosette appearing early, the blades ovate-lanceolate, usually less pubescent 
than those of the culms. 
In the original description Dr. Bolander states: ‘“‘The whole plant is like velvet to 
the feel. There are, however, some specimens which are rather smooth.’ This 
smoother form is represented by part of Merrill 157, one tuft of which has lower blades 
nearly glabrous, but sheaths and upper blades nearly as velvety as in the type, while 
other specimens of this collection are fully as villous. The Bolander type collection 
represents about the average of the species. Some of the specimens cited below are 
longer villous than the type and some few are smoother, 
A specimen from Banff, Alberta, McCalla 2318, ‘on tufa and old bogs in warm 
sulphur stream; alt. 4,500 ft.,’’ has 
short, early-branching culms, broad 
leaves and small panicles like P. ther- 
male, but the pubescence is of sparser 
long hairs, somewhat harsh and promi- 
nently papillose as in P. pacificum. 
Fria. 243.—P. thermale. From 
type specimen, 
DISTRIBUTION. 
Wet saline soil in the immediate 
vicinity of geysers and hot springs 
ascending to 2,500 meters, Alberta to 
Wyoming and California. 
Auperta: Banff, McCalla 2318. 
Montana: Lo Lo Hot Springs, Williams & Griffiths 306. 
Wyomina: Yellowstone National Park, Chase 5252; /Titchcock 1902, 2061, 2086, 
Mearns 3061, 4050, 4166, 4203, 4789, 4870, 4983, 5064, 5110, 5134, Merrill 157, 
Fic, 244.—Distribution of P. thermale. 
