Scirpus. CYPERACEyE. 217 



t.lie spikelets in a terminal (or apparently lateral) involucrate cluster or compound 

 umbel-like {)anicle, or solitary. 



A cosmopolitan genus of nearly 250 species, of wliieh about 30 are found in tlie United States. 



§ 1. Spikelet solitari/, small, with a siuf/le erect involucral bract : bristles none : 

 stems low and slender. — Lsolepis, Bentli. 



1. S. riparius, Spreng. Stems tufted, from fdjrous roots, very slender and often 

 setaceous, 2 to G or rarely 10 inches high, sheathed at base, the upper sheath usually 

 bearing a short slender leaf : involucral bract 1 to 10 lines long or nearly wanting : 

 spikelet ovate to oblong-ovate, 1 ^ to 2i lines long : scales pale or often deep brown, 

 with a palo prominent midvein, concave, obtuse or pointed : stamens usually 3 : 

 stylo 3-cleft : nutlet triangular-obovoid with distinct angles, the sides convex, smooth 

 or minutely granular, not striate nor ribbed, dark brown when mature, less than half 

 a line long. — l>enth. Fl. Austr. vii. 327. lsolepis riparia, K. Br.: Hook. f. Fl. 

 Tasm. ii. 89, t. 145. S. Savii, Reichenb. Icon. Fl. Germ, viii, t. 301. lsolepis 

 leptocanlis, Torr. Pacif. K. liej). iv. 153. -S'. p)/gm(tns, Gray, Proc. Amer. Acad. vii. 

 31)2. S. setaceiis, Linn., var., Doeckeler, Linniea, xxxvi. 500. 



Frequent in niarsliy nlaces near tlie coast from Santa Barbara to Oregon ; also in South America, 

 Australia, Africa and the Mediterranean region. 



2. S. carinatus, Gray, 1. c. IJesembling the last in habit, the slender stems 

 triangidar and ciiannelled, 1 to 4 inches high, with a short leaf at base : spikelet 

 (rarely 2 or 3) greenish or tinged with brown, 5- lO-flowered ; scales in 4 ranks, 

 very broadly ovate, strongly carinate and boat-shaped, acute, gibbous in fruit and 

 retaining the brown nutlet, which is very broad, acutely triangular, smooth, over 

 half a line long, with a broad scar at the summit. — Boeck. 1. c. 498. lsolepis cari- 

 nata, Hook. Sc Arn. ; Torr. (Jyp. 349. /. koilolepis, Steud. Cyp. 318. 



In swainiis about S.in Francis-o. abundant witb the last {Bolandrr); Santa Rosa Creek {Bigc- 

 loiv); Mendocino County {Bu/dudcr); in the Gulf States, from Alabama to Arkansas and Texas. 



§2. Bristles present, retrorschj barbed or ciliate, not elongated: stems mostly 

 tall and stout. — Eusciupu.s, Benth. 



* Lijlorescence apparently lateral, with a single erect involucral leaf. 



H— Stem terete or nearly so. 



++ Stem leafy at base : spikelets in a sessile cluster. 



3. S. Nevadensis, Watson. Stems clustered, from a running rootstock, a foot 

 or two high, very slender, somewhat llattened above : leaves nearly equalling the 

 stem, deeply channelled or revolute, very rough on the margins, sharply acute : 

 spikelets 1 to 8, ovate-oblong, acute, 4 to 10 lines long; scales brown and shining, 

 ovate, slightly carinate, acutish : bristles 1 to 3, not half the length of the nutlet : 

 style 2-cleft : nutlet broadly ovate, plano-convex, acute;, a lino long, — Bot. King 

 Exp. 3G0. 



Borders of Mono Lake, on alkaline soil (Brewer, n. 184G); at Soda Lake, Nevada, JVntson. 



++ ++ Stem leafless or nearly so : spikelets umbelled. 



4. S. lacustris, Linn. Stem stout and tall, from creeping rootstocks, terete or 

 very obtusely triquetrous above, leafless or the upper basal sheaths with a short 

 terete leaf: involucral bract stout, shorter than the iidlorescenco : spikelets numerous, 

 solitary or more or less clustered, in an irregularly compound umbel, oblong-ovoid, 

 3 to 6 lines long ; scales broadly ovate, very obtuse or usually emarginate and mucro- 

 nate, ciliate : bristles usually 6, slender with scattered barbs, about equalling the 

 obovato plano-convex nutlet: style usually 2-cleft. — Peichenb. 1. c, t. 306-308; 

 Boeck. 1. c. 712 ; Bonth. 1. c. 33;3. S. vaiidm, Vahl. 



