CLASS IV. 147 



shorter than the calyx and coriaceous : rudiments opposite, senile, "e- 

 sembling valves : nectary lateral. (ribbon-grass.) 



C. Spikelets many-flowered. 



PO'A. Spikelets oblong or linear, compressed, many-flowered; ca- 

 tyx shorter than the florets : corolla herbaceous, awnless, often arach- 

 noid at the base; lower valve scarious at the margin. (spear-grass.) 



Exotic. 



SORG"HUM. Florets in pairs, one perfect, with a 3-valved corolla, 

 and sessile; the other staminate or neutral, and pedicelled. (broom 

 corn.) 



DAC"TVLIS. Spikelets aggregated in unilateral heads, many flower- 

 ed : calyx shorter than the florets, with one large glume, keeled, point 

 ed: corolla with the lower valve keeled, emarginate, mucronate.-- 

 (orchard grass.) 



AVE'NA. Calyx 2-valved; 2,3, or many flowered : corolla valves 

 mostly bearded at the base, lower one torn, with a twisted awn on the 

 back: glumes membranaceous, and somewhat follicle-like; seed 

 coated. (oats.) 

 mm D. Flowers in spikes. 



TRI'TICUM. Calyx 2-valved, about 3-flowered ; florets sessile on the 

 teeth of the rachis, obtusish and pointed ; glumes beardless, or inter- 

 ruptedly bearded. (wheat.) 



SFCA'LE. Calyx 2-valved, 2 or 3-flowered : spikelets sessile on the 

 teeth of the rachis, with the terminal floret abortive: glumes subulate, 

 opposite, shorter than the florets : corolla with the lower valve long- 

 awned. (rye.) 



CLASS IV. TETRANDRIA. FoUT StamOlS. 



Order 1. Monogynia. One pistil. 



A. Flou-ers superior. 



(1-petaled.) 



CEPRALAN"THUS. Inflorescence in a head : general calyx none ; 

 proper calyx superior, minute, angular, 4-cleft: corolla funnel-form: 

 receptacle globular, hairy : seed solitary, oblong. (button-bush.) 



HOUSTO'NIA. Calyx half superior, 4-toothed": corolla salver-form, 

 4-cleft ; capsule 2-celled, many-seeded, opening transversely. (inno- 

 cence.) 



(k-petaled.} 



COR"NUS. Calyx 4-toothed : drupe with a 2-celled nut Some spe- 

 cies have a 4-leaved involucrum. (dogwood, false box.) 



Southern. 



LY'CIUM. Corolla tubular, having the throat closed by the beards of 

 the filaments : stamens often 5 : berry 2-celled ; many seeded. (mat- 

 rimony.) 



