008 CXLVTT. GRAMINE.li, 



lower floral glume generally resembling the invol .-glumes in structure 

 and nervation ; upper floral glume firmer, at length rigid, often 

 chartaceous to crustaceous. 



Shrubs; flowers dioecious 1. Spinipbx. 



Herbs ; flowers not dioecious. 



Spikelets 2-flowered, the upper 2-sexual; lower male or 

 neuter, rarely (Isachnc) both fertile. 

 Mature spikelets persistent on their pedicels, sur- 

 rounded singly or in clusters by an involucel of naked 

 or plumose bristles or spines which fall along with 

 the spikelets. 



Involucel of bristles 2. PENmsETUM. 



Involucel of spines connate at the base 3. OENcnuus. 



Mature spikelets falling entire and singly from the 

 tips of their pedicels. 



Spikelets subtended by an involucel of bristles 4. SETARfA. 



Spikelets not subtended by bristles. 



Branches of the panicle produced beyond the 

 uppermost spikelets ; lower invol.-glume 



minute, orbicular, white, hyaline 5. CHAji.EiUPnis. 



Branches of the panicle not produced beyond 

 the uppermo.st spikeleLs. 

 Glumes 4, all distinct or 3 distinct and 1 

 obsolete (in Panicum suheghcme sometimes 

 2 obsolete). 



Invol. -glumes separately deciduous 6. IsaChne. 



Invol. -glumes not separately deciduous. 

 Spikelets awned (except in Tricholoena 

 TenerijfcB). 



Spikelets densely silky 7. TRicnoL.E5r.\. 



Spikelets not silky. 



Palea of lower floral glume 



very short, 2-fid 8. Axonopus. 



Palea of lower floral glume 



entire or 9. Oplismbncs. 



Spikelets not awned except in 

 Panicum stagninum (mucronate or 

 apiculate in a few species of 

 Panicum and in Eriochloa). 

 Lower invol. -glumedistinct (except 

 in Panicum suhcylume) ; in- 

 florescence paniculate 10. Panicd.m. 



Lower invol.-glumc minute (rarely 

 absent) ; nerves of lower floral 

 glume 5-7, sti'aight, prominent; 

 inflorescence usually digitate ... 11. DioiTAUfA. 

 Lower invol.-glume absent; nerves 

 of lower floral glume b or 

 fewer, the side-nerves curved. 

 Spikelets not thickened at the 



base 12. Paspalu.m. 



Spikelets thickened at base ... 13. EKiociiLo.i. 



Teibb 2. ANDROPOGONE.ffi. Spikelets usually in pairs, one sessile, 

 the other petlicoUate, rarely o-iiate or solitary on the axis of a usually 

 spike-like raceme. Invol. -glumes more or less rigid and firmer than 

 the floral glumes, the lower always longer than the florets ; floral 

 glumes membranous, often hyaline, that of the upper floret usually 

 awned or reduced to an awu. 



