GRASS FAMILY. 97 
Flowering scale of some other structure. 
Flowering scales 1-3-nerved, all with perfect flowers, or the uppermost with a 
staminate flower only or empty. 
Panicle branches spirally arranged. 
Panicle branches simple, in spike-like racemes. 63. Diplachne. 
Branches of the panicle mostly again divided. 
Spikelets loosely 2-4-flowered; conical rachilla articulated. 
64. Molinia. 
Spikelets densely 2-7o-flowered; rachilla not articulated; ligule or 
throat of sheath bearded. 65. Eragrostis. 
Primary branches of the panicle distichous, usually branched again at the base. 
Panicle spike-like or much contracted. 
Second scale broader than the 2 flowering ones. 66. Eatonia. 
Second scale not broader than the 3-7 flowering ones. 67. Koeleria. 
Panicle diffuse, with long slender branches. 68. Catlabrosa. 
Flowering scales 3-many-nerved, with 2 or more of the upper scales empty, 
appressed, convolute around each other. 
Stamens 3; upper sterile scales usually club-shaped. 69. Melica. 
Stamens 1-2; sterile scales not club-shaped. 70. Korycarpus. 
Flowering scales 5-many-nerved, each with a perfect flower, or the upper sometimes 
abortive. 
Keel of the palet winged or with a linear appendage. 71. Pleuropogon. 
Keel of the palet not appendaged. 
Scales more or less strongly compressed and keeled. 
Empty basal scales 3-6; spikelets flat, 2-edged. 72. Uniola. 
Empty basal scales 2; spikelets flattened. 
Panicle contracted; spikelets dioecious. 73. Distichlis. 
Panicle open; spikelets perfect. 
Flowering scales herbaceous, awn-pointed; spikelets collected 
in one-sided clusters. 75. Dactylis. 
Flowering scales scarious-margined; rachis glabrous or with 
webby hairs. 
Spikelets large, cordate. 74. Briza. 
Spikelets mostly smaller, not cordate. 
Empty scales projecting beyond the uppermost flower- 
ing ones; arctic grass. 78. Dupontia. 
Uppermost scales exceeding the empty ones; flowering 
scales 2-10, mostly webby at base. Poa. 
Flowering scales membranous; rachis hirsute with stiff hairs, 
extended into a hairy appendage. 80. Graphephorum., 
Seales rounded on the back, at least below. 
Stigmas placed at or near the apex of the ovary. 
Flowering scales with a basal ring of hairs, prominently 7-nerved, 
toothed at apex; water grass. 79. Scolochloa. 
Flowering scales naked at the base: 
Obtuse or subacute and scarious at the apex, usually toothed. 
Plainly 5-7-nerved ; styles present. 81. Panicularia, 
Obscurely 5-nerved; no style or awns. 82. Puccinellia,. 
Acute, pointed or awned at apex; not webby. 83. /es/uca. 
Stigmas plainly arising below the apex of the ovary; spikelets large, 
usually drooping; scales mostly awned. 84. Bromus. 
Tribe XI. HoRDEAE. 
Stigma 1; spike unilateral; spikelets 1-flowered, narrow. 85. Nardus. 
Stigmas 2; spike symmetrical. 
Spikelets solitary at the notches of the rachis. 
Flowering scales with their backs turned to the rachis. 86. Lolrum. 
Flowering scales with their sides turned to the rachis. 
Spikelets 1-2-flowered in slender articulate spikes. 87. Leplurus. 
Spikelets 2-many-flowered in stout inarticulate spikes. 88. Agropyron. 
Spikelets 2-6 at each joint of the rachis; scales mostly long-awned, 
Spikelets 1-flowered or with the rudiment of a second flower. 89. Hordeum. 
Spikelets 2-many-flowered. : 
Empty scales a little smaller than the flowering ones. 90. Elymus. 
Empty scales very small or none. gt. Hystrix. 
Tribe XII. BAMBUSEAE. 
Tall canes with large flat spikelets in panicles or racemes. 92. Arundinaria. 
TRIPSACUM L. Syst. Ed. 10, 2: 1261. 1759. 
[Dicirarta Heist.; Adans. Fam. Pl. 2: 38. [1763.] 
Tall perennial grasses with thick spotstocks: rather broad flat leaves and monoecious 
flowers. Spikelets 1-2-flowered, in terminal or axillary, solitary or clustered, elongated 
spikes. Staminate spikelets in 2’s at each node of the axis, 2-flowered, consisting of four 
scales, the two outer coriaceous, the two inner thinner, the palet hyaline; stamens 3. Pis- 
tillate spikelets in excavations at the lower joints of the spike, 1-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 3 species, natives of tropical and temperate America, Besides the following, another 
occurs in the southern United States. 
“I 
