322 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
a feathery panicle, the small narrow spikelets margined with silky white hairs 
6 to 8 mm. long, the general appearance unlike that of any other species of 
Paspalum. 
Banks and steep slopes, Costa Rica and the Lesser Antilles to northern South 
America, Originally described from St. Christopher. Paspalum saccharoides 
was described from the West Indies. Moenchia speciosa was based on Panicum 
saccharoides, 
Guadeloupe, Dominica, Martinique, Grenada, Trinidad, and Tobago. 
36. PANICUM L. 
Inflorescence paniculate (rarely racemose) ; spikelets pedicellate, biconvex; 
first glume present; sterile lemma usually inclosing a hyaline palea, sometimes 
a staminate flower; fruit chartaceous-indurate, the margins of the lemma in- 
rolled. 
The North American species of this genus have been described in two earlier 
papers* in which a detailed citation of specimens is given. In the present 
paper there is given only a résumé collated from these two papers. 
Axis of branchlets produced beyond the base of the uppermost spikelet as a 
point or bristle 1 to 6 mm. long. (Subgenus PaurocHarTIuM. ) 
First glume rounded or truncate; second glume about as long as fruit. 
3. P. chapmani. 
First glume acute; second glume about two-thirds as long as fruit. 
Spikelets 1.5 mm. long; blades involute____.______ 1. P. distantiflorum. 
Spikelets 2 mm, long; blades flat__ — 2. P. utowanaeum, 
Axis of branchlets not produced into a bristle. (In P. geminatum the somewhat 
flattened axis pointed but not bristle-form. ) 
Basal leaves usually distinctly different from those of the culm, forming a 
winter rosette; culms at first simple, the spikelets of the primary panicle 
not perfecting seed, later usually becoming much branched, the small 
secondary panicles with cleistogamous fruitful spikelets. Mostly delicate 
grasses with small open primary panicles (narrow in P. neuranthum and 
P. caerulescens), the small elliptical or obovate, obtuse spikelets (pointed 
in P. fusiforme) on capillary, often flexuous pedicels. (Subgenus Dt-. 
CHANTHELIUM. ) 
Foliage soft and lax, the flat blades prominently ciliate; plants branching 
from the base, finally forming rosettes or cushions. (LAXIFLORA.) 
Spikelets papillose-pilose; sheaths retrorsely pilose____50. P. xalapense. 
Spikelets glabrous; sheaths not retrorsely pilose, 
Blades glabrous on the surface_ _-01. P. polycaulon. 
Blades pilose on the surface___ - -- _-52. P. strigosum. 
Foliage not soft and lax; plants branching from the culm nodes. 
Spikelets glabrous; plants glabrous throughout; autumnal phase erect, 
not bushy-branching. (DicHoTomMa in part.) 
Plants delicate, tufted, not over 25 cm. tall; spikelets 1.2 mm. long. 
67. P. chamaelonche, 
Plants slender but not delicate, usually at least 50 cm. tall; spikelets 
1.6 mm. long or more, 
Spikelets not over 16 mm. long; panicles narrow; plants glaucous 
bluish green______._--_-__- 60. P. caerulescens. 
Spikelets 2 mm. or more long; panicles open____60. P. roanakense. 
*Contr. U. S. Nat. Herb. 15: 1910; 17: 459-539. 1915, 
