GENUS i. 



GRASS FAMILY. 



i ii 



Empty scales shorter than the uppermost flowering 



ones. 92. Poa. 



Rachilla of the spikelets hirsute, extending into a hairy 

 appendage ; flowering scales membranous. 



95. Graphephontm. 

 Scales rounded on the back, at least below. 



Flowering scales with basal ring of hairs, apex toothed. 



94. Scolochloa. 

 Flowering scales naked at the base. 



Flowering scales obtuse or subacute and scarious at the apex, 



usually toothed. 



Manifestly 5-7-nerved ; styles present. 96. Panicnlaria. 

 Obscurely 5-nerved ; no styles. 97. Puccinellia. 



Flowering scales acute, pointed, or apex awned. 98. Festuca. 

 Stigmas arising below apex of the ovary ; scales rarely awnless. 



99. Bromus. 



Tribe XL HORDEAE. 



Stigma i ; spike unilateral ; spikelets i-flowered, narrow. 

 Stigmas 2 ; spikes symmetrical. 



Spikelets solitary at the notches of the rachis. 



Flowering scales with their backs turned to the rachis. 

 Flowering scales with their sides turned to the rachis. 



Spikelets i- or 2-flowered, in slender articulate spikes. . 

 Spikelets 2-many-flowered, in stout inarticulate spikes. 

 Spikelets 2-6 at each joint of the rachis ; scales mostly long-awned. 

 Spikelets i -flowered, or with the rudiment of a second flower. 

 Spikelets 2-many-flowered. 



Rachis of the spike articulated, readily breaking up. 

 Rachis of the spike continuous, not breaking up. 



Empty scales a little smaller than the flowering ones. 

 Empty scales very small or none. 



Tribe XII. BAMBUSEAE. 



Tall canes with large flat spikelets in panicles or racemes. 



100. Ngrdus. 



101. Lolium. 



102. Leptunis. 



103. Agropyron. 



104. Hordeum. 



105. Sitanion. 



1 06. Ely in us. 



107. Hystrix. 



1 08. Arundinarla. 



i. 



TRIPSACUM L. Syst. Nat. Ed. 10. 1261. 1759. 



Tall perennial monoecious grasses with thick rootstocks, rather broad flat leaves and 

 spicate or racemose inflorescence. Spikelets i- or 2-flo\vered, in terminal or axillary, solitary 

 or clustered, elongated spikes. Staminate spikelets in 2's at each node of the axis, 2-flo\vered. 

 consisting of four scales, the two outer coriaceous or membranous, the two inner thinner, the 

 palet hyaline; stamens 3. Pistillate spikelets in excavations at the lower joints of the spike, 

 l-flowered; stigmas exserted; style slender. Grain partly enclosed in the excavations of the 

 spikes, covered in front by the horny exterior lower scale. [Name from the Greek, in allusion 

 to the polished outer scales.] 



About 7 species, in tropical and temperate America. Type species : Tripsacum dactyloides L. 



i. Tripsacum dactyloides L. Gama- Sesame- 

 or Bull-grass. Fig. 254. 



Coi.r dactyloides L. Sp. PI. 972. 1753- 

 Tripsacum dactyloides L. Sp. PI. Ed. 2, 1378. 1763. 

 Tripsacum dactyloides var. monostachyum Wood, Class- 

 book Ed. 2, 623. 1847. 



Culms stout, erect, 4-8 tall. Leaves smooth and 

 glabrous; blades i or more long, i'-iA-' wide, long- 

 acuminate, truncate or subcordate at the base; spikes 

 terminal and in the upper axils, solitary or 2 or 3 

 together, 4'-$' long, the lower spikelets pistillate, the 

 upper staminate and very numerous ; outer scales of 

 the staminate spikelets linear and obtuse, 3*"-5i" 

 long, faintly many-nerved ; exterior scale of the 

 pistillate spikelets horny, shining, closely appressed 

 in fruit. 



In swamps or along streams, Rhode Island to Ne- 

 braska, south to Florida, Texas and Mexico, the southern 

 Bahamas, Haiti and South America. June-Sept. 



2. COELORACHIS Brongn. in Duperr. Voy. Coq. Bot. Phan. 64. 1829. 



Mostly tall perennials, with narrow flat leaves and cylindric jointed spikes, terminal and 

 from the upper axils. Spikelets in pairs at each node of the excavated rachis, one sessile 



