36 CLASS III. ORDER II. 



ORDER II. DYGVNIA. 



A. SpiMets l-Jlowered ; corollas without abortive rudiments of flowers at the 



base. [ Calyx and carolla different in texture.] 



Leer"sia. Calyx ; corolla 2-valvqd, closed ; valves compressed, boat-shap- 

 ed ; nectary obovate, entire, collateral; stamens varying in number, (cut- 

 grass.) 



Sac"chauum. Calyx involucred with long wool at the base, 2-valved ; corolla 

 1 or 2 valved; stamens I to 3. (sugar-cane.) 



[Calyx and corolla of similar texture— flowers in spreading panicles] 



AGR0s"tis. Calyx herbaceous, 2-valved, 1-flowered, valves acute ; a little 

 less than the corolla; corolla 2-valved, membranaceous, often hairy at the base ; 

 stigmas longitudinally hispid or plumose, florets spreading; nectary lateral; 

 seed coated, (redtop.) 



Arun"do. Calyx 2-valved, unequal, membranaceous, surrounded with hair 

 at the base ; lower valve mucronate or slightly awned. Sometimes there is a 

 pencil-form rudiment at the base of the upper valve, (reed.) 

 [ Calyx and corolla of similar texture— flowers in compact panicles, often spike- 

 form.] 



Phle'um. Calyx hard, 2-valved, equal, sessile, linear, truncate, picuspidate; 

 corolla enclosed in the calyx, 2-valved, awnless, truncate, (timothy-grass.) 



B. Spikelets l-flowered ; corolla loith \ or 2 abortive rudiments of flowers at the 



base. [Calyx and corolla of similar texture.] 

 Phala'ris. Calyx membranaceous, 2-valved, valves keeled, nerved, equal in 

 length, including the 2-valved pilose corolla. The corolla is shorter than the 

 calyx and coriaceous; rudiments opposite, sessile, resembling valves — nectary 

 lateral, (riband-grass, canary-grass.) 



C. Spikelets many-flowered. [Flowers in 'panicles ; corolla unarmed.] 



Phragmi'tes. Calyx 5 to 7-flowered. The florets on villose pedicels; lower 

 valve elongated, acuminate, involute; upper one somewhat conduplicate. 



Bri'za. Spikelets heart-ovate, many-flowered ; calyx chaffy, shorter than the 

 2-ranked florets; corolla ventricose ; lower valve cordate; upper one orbicular, 

 short. (qub,ke-grass ) 



Po'a. Spikelets oblong or linear, compressed, many-flowered ; calyx shorter 

 than the florets ; corolla herbaceous, awnless, often scarious at the base; lower 

 valve various at the margin, (spear-grass.) 



SoRG^uaM. Florets in pairs, one perfect, with a 3- valved corolla, and sessile, 

 the other staminate or neutral, and pedieelled. (broom-corn.) Ex. 

 [Flowers in panicles ; corolla armed or mucronate.] 



DAC"TyLis. Spikelets aggregated in unilateral heads, many-flowered; calyx 

 shorter than the florets, with one large glume, keeled, pointed; corolla with the 

 lower valve keeled, emarginate, mucronate ; upper valve sub-conduplicate. 

 (orchard-grass.) 



Ave'na. Calyx 2-valved ; 2, 3, or many-flowered ; corolla with 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.) Ex. 



[Flowers in spikes.] 



Lo'uuM. Calyx 1-leafed, permanent, many-flowered; florets in many flower- 

 ed, 2-rowed, simple, sessile spikelets on a rachis; lower valve of the corolla 

 herbaceous-membranaceous, mucronate, or bristled at the Jtip. (darnel-grass.) 



Trit'icum. Calyx 2-valved, about 3-flowered ; florets sessile on the teeth of 

 the rachis, obtusish and pointed ; glumes beardless, or interruptedly bearded, 

 (wheat.) Ex. 



Seca'le. Calyx 2-valved, 2 or 3-flowered; spikelets sessile on the teeth of the 

 rachis, wilh the terminal floret abortive; calyx 2-valved; glumes subulate, 

 opposite, shorter than the florets ; corolla with the lower valve long-awned. 

 (rye.) Ex. 



D. Flowers polygamous. [In panicles.] 



Pan"icum. Calyx 2-valved, 2-flowered; the lower glume generally very 

 small ; the lower floret abortive, 1 or 2-valved ; the lower valve resembling 



