142 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Subgenus DICHANTHELIUM subgen. nov. 
Perennial, from a crown, rarely from short, matted rootstocks, surrounded by a more 
or less well-marked rosette of usually short winter leaves, in spring producing simple 
culms with mostly narrowly lanceolate blades and terminal panicles with numerous 
spikelets, these rarely perfecting seed; the early culms branching at some or all of 
the nodes (in a few species from the base only) after the maturity of the primary pani- 
cles or sometimes before; the branches often repeatedly branching, the short branchlets 
more or less fascicled and bearing usually much reduced leaves; the terminal one or 
two joints of the primary culms often finally falling, the whole producing an autumnal 
form usually strikingly different from the vernal form; the secondary panicles re- 
duced, the latest more or less included in the sheaths, cleistogamous and perfecting 
their grains. 
The type species is ?. dichotomum L. 
In this group there is an intermediate stage of branching, in which the plants do 
not show the characteristic vernal nor autumnal habit. Vernal culms are sometimes 
produced on plants during the branched condition, because of renewal of activity, 
due to increased moisture, excess of nutriment, injury, or other causes. 
SYNOPSIS OF GROUPS. 
Blades elongated, not over 5 mm, wide, 20 times as long as 
wide; autumnal form branching from the base only (from 
the lower nodes in P. wernert)......2222-00+++0-+--++2+-- DepauPERAtTA (p. 151). 
Blades not elongated, (or if so, more than 5 mm. wide and 
autumnal form not branching from base). 
Plants branching from the base, finally forming rosettes or 
cushions, foliage soft and lax; blades prominently ciliate 
except in P. laviflorum......--.-----++-2222 2200 eee LAXIFLORA (p. 158). 
Plants branching from the culm nodes or rarely remaining 
simple. 
Blades long, stiff; autumnal form bushy-branched above. 
Spikelets turgid, attenuate at base; mostly pustulose- 
pubescent; blades conspicuously striate, tapering 
from base to apeX........------------ +2222 ee eee ANGUSTIFOLIA (p. 165). 
Spikelets scarcely turgid, not attenuate at base; blades 
tapering to both ends.........---------------+---- BicKNELLIANA (p. 176). 
Blades not long and stiff (somewhat so in P. oligo- 
santhes, P. malacon, P. commonsianum, and ?. 
equilaterale); not bushy-branched. 
Plants not forming a distinct winter rosette; spikelets 
attenuate at base, papillose........-----.----+---- PEDICELLATA (p. 292). 
Plants forming a distinct winter rosette, spikelets not 
attenuate at base. . 
Spikelets turgid, blunt, strongly nerved (not strongly 
turgid in P. oligosanthes); blades rarely as much 
as 1.5 em. wide (sometimes 2 cm. in P. rav- 
enellit and P. xanthophysum). 
Sheaths, or some of them, papillose-hispid (some- 
times all glabrous in P. helleri); spikelets 3 to 4 
mm. long (2.7 to 3 mm. in P. wilcorianum)...-OLIGOSANTHIA (p. 278). 
Sheaths glabrous or minutely puberulent; spikelets 
1.5 to 2.5 mm. long, unsymmetrically pyri- 
form; culms Wiry.......---------------eee-e LANCEARIA (p. 271). 
