HOW TO KNOW THE GRASSES 



23b. Leaf sheaths with tufts of hairs on the auricles; second glume 

 minutely hairy; spikelets 2.5 — 3.5 mm. long. Fig. 305. 



KNOTGRASS Paspalum distichuzn L. 



Perennial; spreading by long creeping stolons; 

 erect culms 8 — 50 cm. tall; inflorescence of 2 or 

 rarely 3 racemes, each 2 — 7 cm. long and some- 

 what curved, attached together at the summit of 

 the culm; spikelets often with a minute first 

 glume. Knotgrass forms large flat mats in ditches 

 and on shores of rivers and ponds, usually in 

 fresh water areas, rarely also in brackish locali- 

 ties. May — September. Found also in South 

 America and Europe. 



Figure 305 



24a. Inflorescences borne at the tips of the culms and in the axils of 

 the sheaths (sometimes hidden within the sheaths) 25 



24b. Inflorescences borne only at the tips of the culms, none in the 

 leaf axils or hidden in the sheaths 26 



25a. Spikelets 1.5 — 1.8 mm. long, minutely hairy or glabrous. Fig. 306. 



Paspalum setaceuzn Michx. 



Perennial; tufted from a knotty crown; 

 plants 30 — 50 cm. tall; hairy; culms slen- 

 der and erect; leaf sheaths hairy; blades 

 up to 12 cm. long and 2 — 6 mm. wide, 

 '> hairy on both surfaces and the edges; 



inflorescence of 1 or 2 slender, arched 

 racemes, 5 — 7 cm. long; first glume of 

 spikelets lacking. Dry sandy soil and 

 open woods, especially on the Atlantic 

 and Gulf Coastal Plains. July— Septem- 

 ber. 



Paspalum debile Michx. has spread- 

 ing culms, densely grayish hairy foli- 

 age, and minutely hairy spikelets, 1.8 — 

 1.9 mm. long. Most of the foliage is at the base of the plant; upper 

 leaves short. Sandy woods of the Atlantic and Gulf Coastal Plains; 

 Long Island to Mexico and Cuba. 



Figure 306 



180 



