296 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 



6. CAREX L. Sedge. 



(Contributed by Mr. Kenneth K. Mackenzie.) 



Perennials; culms mostly triangular; leaves 3-ranked; plants monoecious or some- 

 times dioecious; flowers solitary in the axils of glumes; spikes pistillate or staminate- 

 or partly both with the pistillate flowers either at the top or bottom of the spikes: 

 perianth none; staminate flowers of 3 (rarely 2) stamens, the filaments filiform; 

 pistillate flowers of a single pistil, with a style and 2 or 3 stigmas; achenes triangular 

 or lenticular, completely surrounded by the perigynium. 



I. Spike solitary. 

 Stigmas 2; achenes lenticular. 

 Plants very densely cespitose; si^ikes staminate at top; perigynia appressed. 



1. C. hepburnii. 

 Plants with slender elongate rootstocks; spikes usually pistillate or staminate; 



perigynia widely spreading at maturity 4. C. gynocrates. 



Stigmas 3 ; achenes triangular. 

 Perigynia widely spreading or reflexed at maturity, conspicuously stipitate; 

 pistillate scales deciduous. 

 Plants densely cespitose; leaf blades involute, 1 mm. wide; staminate flowers 



few; perigynia erect until full maturity 2. C. pyrenaica. 



Plants short-stoloniferous; leaf blades flat, 1.5 mm. wide or more; staminate 



flowers conspicuous; perigynia early deflexed 3. C. nigricans. 



Perigynia appressed or ascending, little if at all stipitate; pistUlate scales per- 

 sistent. 

 Spikes staminate at top. 

 Perigynia short-beaked; leaf blades acicular. 



Perigynia glabrous, the upper half empty 1. C. hepburnii. 



Perigynia puberulent, nearly filled by the achene 29. C. filifolia. 



Perigynia beakless or very nearly so; leaf blades not acicular. 

 Perigynia rounded at apex, many-nerved; scales not chartaceous. 



27. C. leptalea. 

 Perigynia not rounded at apex, 2-ribbed, otherwise nerveless; scales 



chartaceous 28. C. geyeri. 



Spikes entirely staminate or entirely pistillate, the culms dioecious. 



Perigynia strongly pubescent 30. C. scirpoidea. 



Perigynia glabrous 36. C. parryana. 



II. Spikes more than one. 



A. Stigmas 2; achenes lenticular. 



B. Lateral spikes short, sessile, the terminal spike pistillate at top or bottom, or 



throughout. 



C. Perigynia not white-puncticulate. 



Plants with long-creeping rootstocks, the culms arising one or few together; spikes 

 staminate at top or throughout. 

 Sheaths white-hyaline opposite the blades. 



Rootstocks slender, light brownish; culms obtusely triangular, normally smooth; 

 heads dioecious or nearly so; perigynia strongly nerved ventrally. 



6. C. douglasii. 

 Rootstocks stout, blackish; culms sharply triangular, normally rough above; 

 heads not dioecious; perigynia nerveless or nearly so ventrally. 



6. C. praegracilis. 



Sheaths green-striate opposite the blades nearly to the mouth. Heads not dioecious; 



perigynia strongly striate ventrally 7. C. sartwellii. 



