Seirpus.] LXXXVIII. CYPERACE^E. 485 



extending into central Asia, and in western Europe to the Loire and 

 Belgium, and here and there into central Europe. In Britain, only in 

 North Devon and the Channel Islands. PL late in summer. 



11. S. pong-ens, Vahl. (fig. 1102). Sharp S. Very near S. triqueter, 

 but a rather smaller plant; one or two of the sheaths bear narrow, 

 keeled leaves 1 to 3 inches long, the spikelets are few (usually 3 to 6), 

 all sessile, in a close cluster ; the stiff, triangular, outer bract continuing 

 the stem as in S. triqueter. 



In bogs, marshes, and on the margins of pools, chiefly in North 

 America and the West Indies, but occurs in western Europe, and is 

 found on the sandy banks of St. Ouen's Pond, in Jersey. Fl. summer, 

 rather late. 



12. S. triqueter, Linn. (fig. 1103). Triangular Rootstock creep- 

 ing. Stems acutely triangular, 2 or 3 feet high, leafless, except fchat 

 the one or two loose sheaths at the base bear a short lanceolate blade, 

 from a couple of lines to near an inch long. Spikelets usually 8 or 10 

 or even ,more, the central ones sessile, the others stalked, forming a 

 compound lateral cluster or umbel; the stiff, triangular outer bract 

 continuing the stem for an inch or more: Each spjkelet is ovoid, 4 or 5 

 lines long ; the glumes brown, broad, usually notched or fringed at the 

 top, with a minute point. Hypogynous bristles about 5. Style 2-cleft. 

 Nut smooth and shining. 



In marshes, and edges of pools, in central and southern Europe, ex- 

 tending eastward to eastern Asia and Australia, and northward chiefly 

 in western Europe to Denmark; also found in America. Bare in 

 Britain, and limited to the banks of tidal rivers from the Thames to 

 Cornwall. Fl. late in summer. 



13. S. lacustris, Linn. (fig. 1104). Lake S. Rootstock creeping, 

 with stout, erect stems, from 2 or 3 to 6 or 8 feet high, cylindrical at 

 the base, gradually tapering upwards, and sometimes obtusely triangular 

 near the top, with a single short leaf near the base. Spikelets ovoid or 

 oblong, 3 to 6 lines long, rather numerous, in a compound lateral umbel 

 or cluster, the outer bract continuing the stem. Glumes numerous, broad, 

 brown, fringed at the edge, notched at the top, with a little point in the 

 notch. Hypogynous bristles 5 or 6. Style 2- or 3-cleft. Nut smooth. 



On the margins of lakes and ponds, and in watery ditches, in Arctic, 

 temperate and tropical regions over the globe. ' Abundant in Britain. 

 Fl. summer. Two varieties are often distinguished as species, S. lacustris, 

 with a 3-cleft style and smooth glumes, and S. Taberncsmontani, Gmel. 

 (S. glaucus, Sm.), with a 2-cleft style and raised dots on the glumes ; but 

 these characters are very inconstant, and there are often 2-cleft and 3- 

 cleft styles in the same spikelet. The name of S. Duvalii or S. carinatus, 

 Sm., is sometimes given to a variety of S. lacustris with the stems rather 

 more triangular at the top, sometimes to a slight variety of S. triqueter. 

 [There are three principal British forms of this species, S. lacustris 

 proper, with terete green stems, leaves often floating, ciliate anther- 

 tips and compressed nuts; S. Tabemcemontani, Gmel., with glaucous 

 terete stems, scabrid glumes, glabrous anther-tips, and 3-gonous nuts ; 

 S. carinatuSj Sm. , with green stems obtusely three-angled above, glabrous 

 anther-tips, and compressed nuts. This last occurs on tidal river banks 

 in the south of England only.} 



H- S* ^WitjjnuB, Linn. (fig. 1105). Sea -Rootstock creeping. 



