C7PEBACEAE. 71 



top of the scape, or the lowest distant and 



stalked. 

 Perigj'nium vrith a stout 2-toothed beak; plants 



with glabrous foliage. 20. Extensae. 

 Perigynium with a short entire beak or beakless; 



plants with pubescent foliage. 



21. Pallescentes. 

 Pistillate spikes t'ew-several-flowered, often loose. 



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

 usually large. 

 Perigynia finely many-striate. 



22. Oligocarpae. 

 PerigjTiia with few or many, mostly strong 



nerves. 23. Laxiflorae. 



Leaf-blades and stems mostly capillary; bracts 

 mere bladeless sheaths. 24. Digitatae. 

 Perigynia pubescent. 



Exacts mainly reduced to purple, bladeless sheaths. 



25. Pedunculatae. 

 Bracts various, not shepthing. 



Perigynia mostly rounded. 2(5. Montanae. 



Perigynia conspicuously 3-angled. 



27. Triqaetrae. 

 * * Spike solitary, sometimes dioecious. 



Scales of the spikes elongated, leaf dike. 28. Phyllostachyae. 



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



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. Dioicae. 



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. Muhlcnbergianae. 



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

 pistillate in the spikes, or occasionally forming whole spikes. 

 Perigj-nia wingless, the inner face flat. 34. Elongniae. 



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. 



Perig^Tiia conic, or ovoid, not reflexed. 



Plants yellow or yellomsh ; perigynia little inflated. 



2. C. folliculata. 

 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. 

 Pistillate spikes oblong or cylindric, densely many-flowered. 



Pistillate spikes oblong ; achene longer thaoi thick. 



5. C. lupidina. 



