CTPESAGEAE. 71 



top of • the scape,: or the . lowest .• distant and 

 atalked.j.j ■ i. .-. . , , . ■; 



Perigynium with a stout 2-toothed ,beak; plants 

 with glabroijs foliage. . .20.. Extensae. 

 ■ '. Perigynium with a short entire, beak or beakleBs; 



plants with pubescent foliage. 



• .--*•; 21. Pallescentes. 



Pistillate spikes few-several-flowered, often loose. 



Leaf -blades 2-36 mm. wide;' bracts leaf -like, 

 ■ usually large. ■:" r "-' 

 Perigynia finely many-striate. 



"'■''-' 22; Oli'gocarpae. 

 Perigynia with few or many, mostly strong 

 .''nerves.,- M " 23. Laxiflorae. 



Leaf -blades and stems mostly capillary; bracts 

 mere bladeless sheaths. 24. Digitatae. 

 Perigynia pubescent. 



Bracts mainly reduced to purple, bladeless sheaths. ■ 



25. Pedunculatae. 

 Bracts various, not sheathing. 



Perigynia mostly founded. 26. Montanae. 



■ Perigynia conspicuously 3 -angled. 

 ,.,:,:., • ■ • ..,( 27. Triquetrae. 



* * Spike splitary,, sometimes , dioecious. . ... 



, .Scales of the spikes elongated, leaf -like. 28. Phyllosiachyae. 



Scales of the. spikes, short, normal. 29. Leptoceptyalae. 



B. Staminate flowers few, at the summits or bases of the always sessile 

 spikes or sometimes forming whole spikes, or variously intermixed 

 with the pistillate; stigmas always 2; achene lenticular, compressed, 

 ellipsoid or plano-convex. Vignea. ■•: ■ 



Staminate flowers at the summit of the spike. > - • ' ' > 



Spike solitary, terminal. 30. Dioieae. 



Spikes several, clustered. 



Spikes yellowish or brown at maturity, in compound or panicled 

 ..clusters. ... ...•:. .. :, >• 



Perigynia strongly several-nerved, especially on the ,outer face. 



, 31. Vulpinae. 



Perigynia nerveless or faintly nerved. 32. Multiflorae. 

 Spikes green or greenish when mature, aggregated or separated, in 

 simple clusters. • ,'.)■- 33. Muhlenbergianae. 



Staminate flowers at the base of the spike, variously intermingled with the 

 pistillate in the spikes, or occasionally forming whole spikes. 

 Perigynia wingless, the inner; face flat. 34. Elongatae. 



Perigynia with . narrow or broad marginal wings, the inner face con- 

 cave. . 35. Ovales. 



1. LUPULINAE. 



Pistillate-spikes ovoid or globose, few-many-flowered. 



Perigynia subulate, reflexed when mature. 1. C. Collinsii. 



Perigynia conic, or ovoid, not reflexed. 



Plants yellow or yellowish; perigynia little inflated. 

 ■ . v . • ■ ' 2. C. follioulata. 



Plants green ; perigynia much inflated ; staminate spike stalked. 

 Leaves. 4-6 mm. wide ; heads loosely flowered. 



. : : 3, C. intumescens. 



Leaves 6-10 mm. wide; heads globose, dense. 



...... ■•;,■ •'•■', ., , , 4..C. Asa-Grayi r [ 



Pistillate spikes oblong or cylindric, densely many-flowered. 

 Pistillate spikes oblong; achene longer than thick. 



,'• 5. C. lupulina. 



