HOW TO KNOW THE GRASSES 



8b. Perfect spikelet lanceolate, smooth or rough; rachis joint and pedi- 

 cel separate. Fig. 343. 



Manisurus rugosa (Nutt.) Kuntze 



Figure 343 



Perennial; culms from hard, knotty crowns; 

 culms flattened, much branched, 70 — 120 cm, 

 tall, with numerous axillary racemes. Ra- 

 cemes slender, "rat-tail"-like, brownish, 4 — 8 

 cm. long, tapering from the middle toward 

 the base and apex. They break up into in- 

 dividual joints readily, each joint bearing a 

 perfect sessile spikelet and a sterile spikelet 

 on a thickened pedicel. The first glume of 

 the spikelet is strongly corrugated across the 

 width. Wet pine woods and bogs, Atlantic 

 and Gulf Coastal Plains. September. Four 

 other similar species are found in the south- 

 ern states, differing in the degree of rough- 

 ness, pitting, etc. of the first glume. 



9a. One raceme on each peduncle 10 



9b. Several to many racemes on each peduncle 12 



10a. Awns hairy, stiff and strong, 3 — 12 cm. long; awned spikelets 

 bearing a sharp hairy callus at the base 11 



10b. Awns not hairy, thin and delicate, 2 cm. long or shorter; spike- 

 lets disarticulating at the base of the glumes 12b 



11a. One awned and one awnless spikelet falling as a pair; rachis of 

 the raceme disarticulating. Fig. 344. 



TANGLEHEAD Heferopogon contoTtus (L.) Beauv. 



Perennial; tufted; plants 20 — 80 cm. tall; leaf 

 sheaths flattened and keeled; racemes borne 

 at the tips of slender peduncles. The pairs of 

 spikelets at the base of each raceme are all 

 staminate. In the upper portion of the raceme, 

 each pair consists of a sessile perfect spikelet 

 and a stalked staminate spikelet. The sessile 

 spikelet has a long, bent awn and a hairy rachis 

 joint, which is attached below the base of the 

 glumes. This spikelet greatly resembles the 

 floret of some species of Stipa. Attached at the 

 base of the perfect spikelet is a short pedicel 

 bearing an awnless, laterally compressed and 

 winged staminate spikelet. The two spikelets 

 of each pair fall as a unit. Because of the 

 sharp hairy callus and stiff awn, the perfect spikelets may injure graz- 

 ing sheep. A good forage grass when not in fruit. Rocky deserts in 



Figure 344 



179 



