GRAMINE^E. (GRASS FAMILY). 399 



two inferior imperfect ones, or of from two to many flowers, the upper ones or some 

 of them imperfect. The rhachis sometimes produced beyond the upper flower as a 

 stipe-like pedicel or as an imperfect flower. — Poaoe^;. 



Tribe IV. Spikelet one to three-flowered, perfect flower solitary and terminal : glumes 



one-nerved or keeled (sometimes three-nerved in Plialaris). — Phalamde^e. 



# Rhachis articulated above the outer glumes. 



10. Fhalaris. Spikelets one-flowered, compressed, on the densely flowered branches of 



a panicle (in ours). Outer glumes acute, boat-shaped, becoming coriaceous or carti- 

 laginous ; within these the flower consisting of two glumes, sometimes called palets, 

 enclosing stamens and pistil ; below the -flower one or two small scales or bristles. 



11. Hierochloa. Spikelets 3-flowered, in an open panicle : terminal flower perfect, but 



with only 2 stamens ; the two lower flowers male only, each with 3 stamens. Two 

 outer glumes thin and scarious, acutely keeled ; glumes of the male flowers thicker, 

 sometimes short-awned, each enclosing a narrow, thin, bifid, two-keeled palet ; the 

 upper or perfect flower has a one-nerved glume in place of a palet. 

 # # Rhachis articulated below the spikelet. 



12. Alopecurus. Spikelets one-flowered, crowded in a cylindrical spike. Outer glumes 



strongly compressed, boat-shaped, keeled, nearly equal, frequently united at base ; 

 flowering glume shorter, keeled, with a slender dorsal awn, frequently more or less 

 united below by the opposite margins and enclosing the stamens and styles. 



Tribe V. Spikelet perfect, one-flowered ; rhachis often prolonged beyond the flower as a 

 bristle or stipe. — Agrostide.e. 



* Spikelets paniculate : rhachis not produced beyond the flower : beard of the flowering 



glume terminal. 



13. Aristitla. Spikelets in a spicate or open branching panicle, generally on filiform 



pedicels. Outer glumes unequal, often bristle-pointed : flowering glume narrow, 

 rolled around the flower, terminating with a trifid awn, or apparently 3-awned : palet 

 small and thin, enclosed in the flowering glume. 



14. Stipa. Spikelets terete. Outer glumes membranaceous, keeled: flowering glume 



narrow, coriaceous, rigid, involute, with a simple twisted awn from the apex : palet 

 small and thin. 



15. Oryzopsis. Eesembling Stipa, but the flowering glume shorter and broader, often 



oblique at top, and the awn usually short, slender and very deciduous. 



16. Mnhlenbergia. Spikelets small, articulated above the glumes. Outer glumes vari- 



able in size, from minute to nearly as large as the flowering glume, sometimes bristle- 

 pointed, keeled, persistent, thin : flowering glume 3 to 5-nerved, rigid or thinnish, 

 mucronate or awned, sometimes with a long capillary awn from the apex between the 

 short teeth, frequently pubescent below : palet about as long as the flowering giume 

 and of the same texture. 



* * Spikelets in a dense spike-like cylindrical panicle : rhachis produced beyond the flower 



in a bristle, or naked : flowering glumes awnless, or produced in 1 to 3 straight bristles. 



17. Phleum. Outer glumes one-nerved, mucronate or short-awned : flowering ^iume 



membranaceous, shorter and broader than the outer glumes, truncate and toothed at 

 the apex : palet hyaline, narrow. 



* * * Spikelets small, loosely spicate or variously paniculate : rhachis not produced beyond 



the flower : glumes awnless and beardless. 



18. Sporobolus. Spikelets rarely 2-flowered. Outer glumes unequal, the lower one 



shorter, 1 to 3-nerved : flowering glume mostly longer : palet about equalling the 

 flowering glume and of the same texture, 2-nerved. 



* * • • Spikelets small, variously paniculate : flowering glume usually with a more or 



less twisted dorsal awn, rarely mucronate or awnless. 

 ■i- No bristle standing opposite the palet. 



19. Aerostis. Outer glumes nearly equal or the lower rather longer, 1-nerved, awnless : 



flowering glume shorter and wider, hyaline, 3 to 5-nerved, awnless. or sometimes 



