ANDROPOGOXE.E. 21 



Stamens 3, rarely 2 or 1. Styles free. Stigmas plumose. Embryo 

 nearly half as large as the unfurrowed obcompressed grain. 



A. Spikeiets homogamous, paniculate, larely spicate, joints of the 

 racliis usually hairy, not much thickened, nor excavated for the 

 reception of the spikeiets. 



a. Axis of the racemes continuous, spikeiets in pairs, rarely in 

 threes. 



b. Racemes in a spikelike panicle, spikeiets awnless. 5. (73) 

 b. Racemes in broad panicles. Spikeiets usually awned. 6. (74) 



a. Axis of racemes articulate. Spikeiets 2-flowered, the spikes 

 or racemes paniculate, main axis elongated. 



b. Spikeiets awnless 7. (75) 



b. Spikeiets awned 8. (76) 



B. Axis of the spikes articulate, somewhat thickened and excavated 

 for receiving the spikeiets ; fertile glumes awnless. 



a. First empty glume of the perfect spikelet flattened or con- 

 vex 9. (84, 88) 



a. First empty glume of the perfect spikelet hard and globular, 

 externally pitted 10. (87) 



C. Spikeiets heterogamous, the sessile perfect (rarely pistillate), 

 the pedicellate staminate, neuter or rudimentary (in Trachypo- 

 gon one spikelet is pedicellate, the other subsessile). 



a. Secondary spikeiets 2-flowered, sessile, awned, pedicellate 

 spikeiets flower-bearing; racemes 3-16, digitate . 1.1. (91) 

 a. Sessile or subsessile spikeiets 1 -flowered, floral glume of the 

 pedicellate spikeiets awnless. (n) 



n. Axis of the racemesim perfectly articulate, not brittle, 

 spikeiets all more or less pedicellate . . . . 12. (92) 

 n. Axis of racemes distinctly articulate; spikeiets both 

 sessile and pedicellate, (o) 



o. First empty glume with abalsam-bearing line along 



the nerves ; racemes solitary ; spikelet awnless. 13. (83) 



o. First empty glume without a balsam-bearing line 



along the nerves, racemes in pairs, often subtended l)y 



a leaf-sheath or bract 14. (94) 



5. (73). IMPERATA Cyrill. PI. Rar. Ic. 2. 26, t. . 11 (1792). 



