SEDGE FAMILY 



269 



2. Eriophorum gracile Koch. 

 Slender Cotton-grass. Fig. 644. 



Eriof'honim gracile Koch; Roth, Catal. Bot. 2: 259. 1800. 

 Culms slender, smooth, nearly terete, spreading 

 or reclining, 6 dm. long or less. Leaves triangular • 

 channeled, the basal ones mostly wanting al 

 flowering time, those of the culm 2 or 3, the upper 

 one with a blade shorter than its sheath. 3 cm. 

 long or less; involucral leaf about 1 cm. long; 

 spikelets 2-4, rarely 6. the slender peduncles 

 pubescent, mostly less than 2 cm. long; scales 

 ovate, gray to nearly black, acutish, the midvein 

 prominent ; achene obovoid-oblong, about 2 mm. 

 long; bristles bright white, 1-2 cm. long. 



In bogs. Transition and Canadian Zones; Calaveras 

 County, California, north to British Columbia, east to 

 Colorado, Iowa, Pennsylvania, New Jersey, and Quebec. 

 Europe and Asia. Type locality: not cited. 



3. Eriophorum angustifoHum Roth. 



Tall Cotton-grass. 



Fig. 



645. 



EriophoniDi atigustifolitim Roth, Tent. 1: 24. 1788. 



Culm stiff, smooth, obtusely triangular above, 

 0.4-0.6 m. tall, all the sheaths blade-bearing. 

 Leaves flat, 3-8 mm. wide, tapering to a chan- 

 neled rigid tip, those of the involucre 2-4, the 

 longer commonly equaling or exceeding the 

 inflorescence, 3-8 mm. wide ; spikelets 2-12. 

 drooping, in a terminal umbel ; rays filiform, 

 smooth ; scales ovate-lanceolate, acute or acumi- 

 nate, purple-green or brown ; bristles numerous, 

 bright white, about 2.5 cm. long, 4-5 times as 

 long as the scale ; achene obovoid, obtuse, light 



brown. 



In bogs, Canadian to Arctic Zones, base of Mount 

 Rainier, north to Alaska, east to Colorado, Illinois, 

 Maine, and Newfoundland. Europe and Asia. Type 

 locality: Germany. Included by authors in E. polysta- 

 chyuni L., an Old World species. 



6. SCIRPUS L. Sp. PI. 47. 1753. 



Annual or perennial very small or very large sedges, with leafy culms or the leaves reduced 

 to basal sheaths. Spikelets terete or somewhat flattened, solitary, capitate, spicate or umbel- 

 late, subtended by a one- to several-leaved involucre or the involucre wanting in some species. 

 Scales spirally imbricated all around, usually all fertile, the 1-3 lower soinetimes empty. 

 Flowers perfect. Perianth of 1-6, slender or rigid, short or elongated, barbed, pubescent or 

 smooth bristles, or none in some species. Stamens 2-3. Style 2-3-cleft, not swollen at the 

 base, wholly deciduous from the achene or its base persistent as a subulate tip. [Latin name 

 of the bulrush.] 



About 150 species of wide geographic distribution. Besides the following some 20 others occur in the 

 eastern L'nited States. Type species, Scirpus lacustris L. 



Bristles not longer or but little longer than the scales, or w-anting. 

 Spikelet solitary, terminal (rarely 2 or 3 in No. 2). 

 Fibrous-rooted low annuals. 



No involucral bract; bristles 6. 

 Involucral bract one; bristles none. 

 Scales of the spikelet keeled. 

 Scales of the spikelet not keeled. 

 Perennials. 



None of tjie sheaths leaf-bearing; no involucral bract. 



One or more of the sheaths leaf-bearing; an involucral bract present or wanting. 

 Involucral bracts shorter than the spikelet or none; terrestrial species. 



Perianth-bristles present. 5. S. caespitosus. 



Perianth-bristles none. 6. .S]. pumdus. 



Involucral bract longer than the spikelet; aquatic species. 7. 5". subtcrimnahs 



