GRASSES OF Porto Rico 375 
leaf-sheaths very broad and reticulated, at least when dry- 
Spikelets about 1.5 mm. long: racemes numerous. 
1. P. densum. 
Spikelets about 2.5 mm. long: racemes 12-18. 
2. P. Underwoodit. 
Third scale dark brown at maturity: basal sheaths not broad 
nor reticulated. 3. P. Boscianum. 
Spikelets pubescent. 
Spikelets elliptic, about one half as wide as long, the pubes- 
cence appressed. 4. P. Helleri. 
Spikelets broadly oval .or obovate, the pubescence spreading. 
Spikelets less than 1.5mm. long. 5. P. hemisphaericum. 
Spikelets 2,5—3 mm. long. 6. P. virgatum. 
Stems slender, creeping at the base: leaf-blades short, rarely more than 
5 cm, long: outer scales of the spikelet without a midnerve. 
9. P. orbiculatum. 
** Spikelets surrounded by a broad toothed margin. 8. P. fimbriatum. 
4. Spikelets narrowly elliptic, lessthan one half as broad as long: rachis of racemes 
barely, if at all, margined. 9. PF. Portoricense. | 
2. Racemes long and slender, arising in pairs at the apex of the stem, rarely with another 
one a short distance below, 10. P. conjugatum, 
1. PaspALuM DENsuM Poir. in Lam. Encycl. §: 32. 1804. 
A single specimen of this species from Porto Rico has been 
seen by the writer, and is the type in the herbarium of Lamarck 
at Paris; it was collected by Ledru. 
2. Paspalum Underwoodii sp. nov. 
A tall perennial with reticulated basal leaf-sheaths, elongated 
leaf-blades and rather dense inflorescence. Stems 8~12 dm. tall, 
erect, rather stout at the base: leaves numerous at the base ; 
sheaths glabrous, the basal ones strongly reticulated, at least when 
dry, rather abruptly narrowed into the blade at or below the mid- 
dle, equitant ; ligule a scarious ring; blades 4-7 dm. long, about 
I cm. wide, long-acuminate at the summit, exceedingly rough on 
the lower surface, densely hirsute on the upper surface, serrulate 
on the margins: inflorescence 1.5-2.5 dm. long: racemes 12-18, 
sessile or nearly so, ascending or nearly erect, the lower ones 7—I0 
cm. long, the rachis including its serrulate wings about I mm. 
wide and more or less setiferous, usually purplish: spikelets in 
Pairs in two rows, on short hispid pedicels, yellowish green, usu- 
ally more or less purplish tinged, glabrous, broadly obovate, 2.5 
mm. long, 2 mm. broad, and about o.8 mm. thick, apiculate, the 
2 outer scales 3-nerved, apiculate, the third scale yellowish-white, 
oval, 2.2 mm. long and about 1.7 mm. wide, minutely striate. 
Type collected by Underwood and Griggs along roadsides, 
