l6. GRAMINEAE 8l 



12. Spikelets surrounded or subtended singly or 2 — 3 together by an involucre 



formed of one or several bristles or spines or of 2 toothed glumes inserted 



below the two empty glumes 13 



Spikelets without an involucre formed of bristles, spines, or toothed glumes. 

 Empty glumes i — 3. Stigmas 2, feathery 16 



13. Involucre formed by two toothed glumes. Stigma i, papillose. Aquatic 



herbs. — Species i. Abyssinia Odontelytrum Hack. 



Involucre formed by one or several bristles or spines. Stigmas 2, feathery. 14 



14. Axis of the spikelet jointed above the persistent involucre. Bristles of 



the involucre stiff and rough. Styles free from the base. Spikelets in 

 spike-like panicles. — Species 30. Some of them (especially S. italica 



Beauv.) are cultivated as cereals Setaria Beauv. 



Axis of the spikelet jointed below the involucre or not jointed ; involucre 

 falling together with the spikelet ; rarely axis jointed above the per- 

 sistent involucre, but then styles united at the base 15 



15. Bristles of the involucre numerous, stiff, thickened and often united at the 



base. Spikelets in spikes or racemes. — -Species 10. Tropics and Egypt. 

 Some have edible seeds ; several are fodder-grasses. Cenchrus L. 

 Bristles of the involucre fine, not thickened at the base. — Species 65. Some 

 (especially the duchn, P. fyphoideum Rich.) are cultivated as cereals, as 

 fodder, or as ornamental plants. (Including Gymnothrix Beauv. and 

 Penicillaria Willd.) Pennisetum Pers. 



16. Spikelets with 2 outer glumes and i flower, or with i outer glume and 2 



flowers. 17 



Spikelets with 3 outer glumes and i flower, or with 2 outer glumes and 2 

 flowers 21 



17. Spikelets containing an hermaphrodite and a male flower, arranged in 



panicles. Glumes a wnless. Styles free. — ^ Species i. South-west Africa 



(Nama-land) Anthaenantia Beauv. 



Spikelets i-flowered, arranged in one-sided, usually digitate or panicled 

 spikes 18 



18. Rachis of the spike prolonged beyond the spikelets. Style i, with 2 stigmas. 



— Species 3. North-west and South Africa. . . . Spartina Schreb. 



Rachis of the spike not prolonged beyond the spikelets. Styles 2, free or 



shortly united 19 



19. Styles united at the base. Flowering glume papery. Upper outer glume 



awTied. Spikelets in digitate racemes. — Species i. East Africa. 



{Siereochlaena Hack.) Chloridion Stapf 



Styles free. Flowering glume cartilaginous 20 



20. Lower outer glume decurrent into a callous swelling. Flowering glume 



mucronate. — Species 6. Central Africa. . . . Eriochloa Kunth 



Lower outer glume without a callus at the base. — Species 15. Tropical 



and South Africa. L^sed as fodder-, medicinal, or ornamental plants. 



F 



