| Stems terete, spongy, leafless, 2–6 ft. high. Spikelets in a broad panicle or umbel 2–4 in. diam. | 12. S. lacustris. |
| Stems acutely trigonous, 1–5 ft. high. Leaves longer than the stems, broad, flat. Spikelets in a terminal umbel; involucral bracts long, leafy | 13. S. maritimus. |
1. S. lenticularis, Poir. Encyc. Suppl. v. 103.—Stems slender, in very wet places 6–18 in. long, elongated and much branched, putting out a small tuft of leaves at each node, often forming large floating masses; in drier situations shorter and stouter, much more sparingly branched, 2–6 in. high. Leaves 1–3 in. long, filiform in floating specimens, stouter in terrestrial ones. Peduncles shorter or longer than the leaves, slender, usually 1 from each tuft of leaves, each bearing a single terminal spikelet. Spikelets variable in size, ⅛–¼ in. long, oblong or oblong-ovoid, obtuse, pale-green; bract (lowest glume) usually longer than the spikelet. Glumes ovate, acute, concave but scarcely keeled, green, sometimes stamed with chestnut-brown. Hypogynous bristles wanting. Stamens 2 or 3. Style-branches 2. Nut three-quarters the length of the glume, obovoid, biconvex, tipped by a minute point, slightly narrowed at the base, smooth, pale.—Benth. Fl. Austral. vii. 826. S. fluitans var. terrestris, Benth. l.c. 325. S. crassiusculus, Cheesem. in Trans. N.Z. Inst. xv. (1883) 300 (not of Hook. f.). Isolepis lenticularis, R. Br. Prodr. 222; Hook. f. Fl. Tasm. ii. 86, t. 145d. Isolepis fluitans, Kirk in Trans. N.Z. Inst. iii. (1871) 166 (not of R. Br.).
North Island: Auckland—North Cape Peninsula, T.F.C; Waikato River, Lakes Whangape, Waikare, and Waihi, Kirk! T.F.C.; Lake Taupo, Kirk! swamps near the base of Ruapehu, Berggren! H. Tryon! A. Hamilton! Petrie! Sea-level to 2500 ft. December–March.
Also in eastern Australia and Tasmania, and very closely allied to the widely spread S. fluitans, L.
2. S. basilaris, C. B. Clarke, MS.—A dwarf species forming dense tufts 1–3 in. diam. Stems very short, ⅛–½ in. long, much branched at the base, leafy. Leaves far overtopping the stems, ½–1½ in. long, sheathing at the base, semiterete above, channelled in front, convex at the back, tip obtuse. Spikelets terminal, solitary or rarely 2 together, concealed amongst the leaves and sometimes almost radical, 110–16 in. long, ovoid, obtuse, pale-green; bract long, leafy. Glumes broadly ovate, obtuse, with broad white membranous margins, and a stout green midrib which is usually produced into a thick excurrent tip. Stamens 2. Style-branches 2. Nut orbicular-obovoid, not angled nor trigonous, slightly compressed, obtuse, smooth but not polished, minutely dotted, lighter dark-brown.—Isolepis basilaris, Hook. f. Handb. N.Z. Fl. 302. I. novæ- zealandiæ, Col. in Trans. N.Z. Inst. xxi. (1889) 102.
