198 CYPERACEAE 



4. SCIRPUS L. Club-Rush. Bulrush. 



Perennials or annuals. Stems leafy or the leaves reduced to mere sheaths 

 at base. Spikelets terete or somewliat flattened, solitary or in heads, spikes or 

 umbels, subtended by an involucre of 1 to several leaves or the involucre wanting. 

 Perianth bristles 1 to 6, barbed or smooth, or none. Stamens 2 or 3. Style 2 or 

 3-eleft, not swollen at the base, deciduous or its base persistent on the achene. 

 Achene triangular, lenticular or ijlano-eonvex. — Species 137, widely distributed 

 in all lands. (Latin scirpus, buh'ush.) 



Bibliog. — Feruald, M. L., Representatives of Scirpus maritimus in America (Rhod. 2:239, — 

 1900). Cliase, A., N. Am. allies of Scirpus lacustris (Rhod. 6:65-71, — 1904, with two excellent 

 plates, 52 and 53). 



Spikelets solitary and terminal ; stems low, slender. — Subgenus Isolepis. 

 Annual ; involueral bract present. 



Scales obtuse or merely acute 1. S. cernuus. 



Scales acute, shortly beaked, strongly keeled 2. S. carinatus. 



Perennial; involucral bract none 3. S. pauciflorus. 



Spikelets in clusters; perennial. — Subgenus Euscirpds. 



Stems low; achene longitudinally ribbed and horizontally striate 4. S. setaceus. 



Stems tall; achene not longitudinally ribbed. 



Bristles rctrorsely barbed or ciliate, rarely wanting. 



Stems terete or nearly so; spikelets congested or umbellate. 



Stems leafy at base; spikelets in a sessile cluster 5. S. nevadeiisis. 



Stems leafless; spikelets in an umbellate or congested cluster. 



Achenes (1 or) 1% to IVi lines long, mostly % to % longer than the scales. 



Umbels capitate or of a few short rays ; bristles barbed 6. S. acutiis. 



Umbels long-rayed; bristles plumose 7. S. calif ornicus. 



Achenes 1 line long, nearh' equaling the scales 8. S. vaUdus. 



Stems S-angled. 



Stems Trith a single head or compact imibel. 



Involucral bract solitary; spikelets densely capitate-clustered, the inflorescence 

 apparently lateral. 



Stems very slender, leafy below; scales awn-tipped 9. S. americanus. 



Stems stout, leafless or mostly so; scales truncate or obtuse, quite awnless 



or with a minute point 10. S. olneyi. 



Involucral leaves several, f oliaceous ; inflorescence terminal, the spikelets capi- 

 tate, or in an umbel with unequal mostly short rays; leaves mainly 

 basal. 



Awn of scale glabrous, smooth; achene plano-convex 11. .S'. cnmpestris. 



Awn of scale minutely scabrid ; achene as if trigonous, in reality flat on 



one face, carinate-eonvex on the other 12. S. fliivwtiUs. 



Stems bearing a panicle of irregular umbels, leafy to the top. 



Pedicels or raylets erect or spreading, bearing few to several sessile spikelets. 



Achenes rounded on the back; bristles 4 13. S. microcarpus. 



Achenes angled on the back; bristles 6 14. S. congdonii. 



Pedicels drooping, bearing a single spikelet 15. S. lineatus. 



Bristles with the barbs pointed upward ; mature heads conspicuously hairy on account 

 of the elongated bristles 16. S. crinigir. 



1. S. cernims Vahl. Slender Club-Rush. Stems tufted, filiform or seta- 

 ceous, 2 to !) inches high, sheathed at base, the uppermost sheath often bearing 

 a short slender blade ; involucral bract 1 to 3 lines long or almost none : spikelet 

 solitary, oblong-ovate, 1 to IVU or 2 lines long; scales round-ovate, concave, 

 obtuse or merely acute, lincate-carinate ; style 3-cleft ; achene brown, i'^ line long, 

 obovoid, flatfish on one side, convex-rounded and with a fine median ridge on the 

 other, finely or somewhat obscurely papillate, apieulate. 



Springy or marshy places near the coast, from San P>ernardino Valley to 

 Humboldt Co. and north to Oregon. All continents. 



Locs. — Elsinore, McClatchic 24: San Bernardino, Parish; Neponset, Salinas River, Abrams 

 4025; Carmel, Ferg-usan 297; Montara I't., Copchind 3315; Oakland. Bnlauder; Lake Merced, 

 San Francisco, Greene; Tiburon, Harriet Walker; Olema, Davy 4356; Eureka, Tracy 816. 



