TRIANDRIA DIGYNIA. 299 



glumes cuspidate ; corolla bearded at the base ; inferior valve 2-tooth- 



ed, with a twisted awn between the teeth; superior valve obtuse, 



entire. 

 >6. TRISETUM. calyx 3 5-flowered, membranaceous, as long as the 



florets. Inferior valve of the corolla with two bristle-form teeth at 



the tip, awned below the division of the teeth. 

 57. BROMUS. Spikelets oblong, distichous, many-flowered; calyx 



shorter than the florets. Inferior valve of the corolla bifid, with a 



bristle between the teeth a little below the tip ; superior valve sub- 



conduplicate, ciliate. 



4. Inferior valve of the corolla awned on the back. 



. AIRA. calyx 2 3-flowered, longer than the florets. Inferior valve 

 of the corolla eroded or many-toothed, awned on the back below the 

 middle. 



b. Flowers spiked. 



1. Calyx l-valved. 



"tef. LOLIUM. Spikelets sessile on a rachis, many-flowered ; calyx of 1 

 glume. Inferior valve of the corolla herbaceo-membranaceous, mu- 

 ^ronate, or with a short bristle at the tip. 



*^*' 2. Calyx 2-valved. 



60. KLEUSINE. Spikes digitate, unilateral ; calyx membranaceous, 4 

 6-flowered ; glumes obtuse, unequal ; corolla membranaceous, un- 

 equal, unarmed ; inferior valve carinate, the superior concave on the 

 back. Ssed triangular, transversely rugose. 



51. AGROPYRON. Spikelets sessile on the teeth of the rachis, 39 

 flowered. Glum, lanceolate, carinate. Inferior valve of the corolla 

 mucronate, or terminating in a subulate bristle. 



n2. ELYMUS. Spikelets two or more at each joint of the rachis, 39- 

 flowered. Glum, (involucrum) germinate, subulate. Inferior valve 

 of the corolla entire, mucronate, or with a short bristle at the tip. 



* * Terminal florets abortive, or mere rudiments. 



63. ATHEROPOGON. Spikes in a unilateral raceme. Cal. 2-valved, 

 membranaceous, 2-flowered ; inferior glume setiform. Perfect floret 

 2-valved ; inferior valve 3-toothed, or 3-bristled ; superior valve bifid. 

 Abortive floret pedicellate, 2-valved ; 3-bristled. 



B. Flowers polygamous. 

 t Panicled. 



64. PANIC UM. Cal. 2-valved, 2-flowered ; the inferior glume oftei, 

 very small. Florets dissimilar; the lower one abortive or anther- 

 ifero'is, 1 2-valved; the inferior valve resembling in texture the 

 glumes ; superior membranaceous. Perfect floret with cartilaginous 

 valves, unarmed. 



1 1 Spiked. 

 * With an involucrum. 



65. SET ARIA. Spikelets with an involucrum of 2 or more bristles at 

 the base. Cal. 2-flowered ; glumes unequal, herbaceous. Inferior 

 floret abortive, 1 2-valved, herbaceous. Superior floret perfect, 



with cartilaginous glumes. 



