Flora of New Zealand Series

Isolepis fluitans (L.) R.Br. Prodr.  1810,  221.

Eleogiton fluitans (L.) Link Hort. Berol.  1,  1827,  285.

Scirpus carsei Kük. in Carse in T.N.Z.I.  48,  1916,  240.

Type: European. Also recorded from Asia, Africa, Malaysia and Australia.

Plants bright green, floating, stems elongated, 12–40 cm., sending out tufts of lvs, rootlets, and flowering culms at each node; terrestrial plants more compact and tufted. Flowering culms 1–10 cm. × c. 0.5 mm., filiform. Lvs in floating forms filiform and flaccid, in terrestrial forms setaceous, = or > culms, < 0.5 mm. wide; sheaths long and membr., dotted with minute red striations, sheath of lowermost lf on culm with oblique orifice, sheath of upper lvs with truncate orifice. Infl. a solitary spikelet; subtending bract <, = or slightly > spikelet, us. floriferous, glume-like or with an elongated mucro. Spikelet 2–4.5 × 1–2 mm., elliptic-ovoid, narrow, pale green or with red markings. Glumes 1.5–3 mm. long, narrow-ovate, obtuse, sides pale and membr., or red-dotted, or evenly red-brown, keel green. Hypog. bristles 0. Stamens 2. Stylebranches 2. Nut c. 1.5 mm. long, slightly < 1 mm. diam., slightly < glume, obovoid, plano-convex, minutely apiculate, slightly stipitate, grey, shining, surface extremely finely reticulate.

DIST.: N. Northland, Kaimanawa and Ruahine Ranges. S. Lake Tekapo.

Swampy ground and lake edges to 750 m. altitude.

HYBRIDISM

× S. prolifundus Carse in T.N.Z.I. 60, 1930, 572. Original localities: Hamilton, Waikato H. B. Matthews; Matatoki, Thames, H. Carse. This presumed hybrid, S. prolifer × inundatus var. major, is represented by a specimen at CANTY, Carse Herb. 345, "in wet place on side of track, Stone Crusher, Matatoki, Thames", H. Carse, Jan. 1929. The specimen resembles large forms of S. inundatus rather than S. prolifer and the fls have 1 stamen and 3 style-branches.

CHR 81251, tidal creek at bridge on Carter's Beach Rd., Buller County, water's edge, R. Mason and N. T. Moar 1665, 24/1/1953, and CHR 81161, Ballarat creek near Westport, damp track, somewhat shaded, R. Mason and N. T. Moar 2275, 4/2/1953 may be S. prolifer × inundatus. The specimens resemble S. inundatus in their slender stems but have 3 stamens, and the spikelets in CHR 81161 are rather long and narrow.

A suite of specimens at CHR, Paekakariki, peat swamp, I. W. Davey, Dec. 1943, comprises normal specimens of S. prolifer and S. inundatus and intermediate specimens smaller than normal S. prolifer but with the long spikelets and 3 stamens characteristic of that sp.

× S. prolifulcus Carse in T.N.Z.I. 60, 1930, 572. Original locality: Glen Eden, Auckland, H. Carse. This presumed hybrid, S. prolifer × sulcatus var. distigmatosus, is represented by CANTY, Carse Herb. 347/12, "Roadside, lower Glen Eden, nr. Auckland" H. Carse, 2/2/1924. The specimen has spikelets larger than usual for S. sulcatus var. distigmatosus and fls with 1 stamen and 2 or 3 style-branches and plano-convex or trigonous nuts.

CHR 122905, Hokitika—south of Hokitika R., wet silt between dredge tailings, A. J. Healy 61/156, 3/2/1961, is a small plant with red-brown glumes characteristic of S. sulcatus var. distigmatosus but resembling S. prolifer in length and width of spikelets. The fls have 1 stamen and 2 or 3 style-branches and the nuts are trigonous or plano-convex.

Apart from the combinations prolifer × inundatus, × sulcatus var. distigmatosus, Cockayne and Allan (Ann. Bot. 48, 1934, 14) also list aucklandicus × cernuus, × antarcticus. CHR 9651, Denniston, V. D. Zotov, 20/1/1936, has been determined as aucklandicus × antarcticus but seems to be either a very fine-lvd form of S. aucklandicus or perhaps a hybrid between that sp. and S. subtilissimus.

S. carsei Kük. in Carse. Type: CANTY 2704, on muddy margins of channel, Lake Tangonge, Kaitaia, H. B. Matthews, Mar. 1913. Carse himself (loc. cit.) thought it a depauperate state of S. fluitans L.

Scirpus productus C. B. Clarke in Addit. Ser. Kew 8, 1908, 28 (S. fluitans L. var. productus (C. B. Clarke) Carse in T.N.Z.I. 57, 1927, 90) was reported (Carse loc. cit.) to occur in N.Z. but specimens so-labelled match either S. fluitans or S. crassiusculus. S. productus was based on a Tasmanian plant and is said to have purplish lf-sheaths and glumes and nuts with ± thickened edges.

INCERTAE SEDIS

Hooker in Fl. N.Z. 1, 1853, 271 lists Isolepis setacea (L.) R.Br. as occurring in N.Z. but from his description he apears to have applied the name to plants of S. cernuus. Under I. setacea, Hooker (loc. cit.) described 3 new vars, var. monandros, var. lenticularis and var. capillaris, but no specimens have been seen. Again, judging from the description, these vars appear synonymous with the following spp.— var. monandros with S. inundatus, var. lenticularis with S. pottsii, and var. capillaris with S. reticularis.

Scirpus ebenocarpus Kirk in T.N.Z.I. 17, 1885, 224, was described as "a tufted species resembling a luxuriant state of S. cartilaginea but easily distinguished by the shining jet-black nuts. The Neck." (Stewart Id). No specimens have been found.

Two specimens, CHR 73796, Molesworth airstrip, Awatere Valley, temporary stream margin, L. B. Moore, 26/2/1953, and CHR 92306, Lake Camp, headwaters of the Ashburton R., Canterbury, dried out edge of lake, R. Mason 4414, 26/3/1956, could not be assigned to any sp. Both were small, tufted and apparently annual; culms 1–3 cm. × 2 mm.; lvs 1–2 per culm, < culms; infl. of 1–2 spikelets; glumes membr., acute, with very prominent, thick keel; hypog. bristles 0; stamen 1; style-branches 3; nut c. 0.6 × 0.4 mm., obovate, trigonous, light brown, surface faintly reticulate. The specimen from Lake Camp has red-brown keeled glumes and is slightly smaller than the one from Molesworth which has green keels. The plants show most resemblance to S. antipodus but differ in being smaller, in having slightly thicker culms, in the glumes not being prominently nerved, and in having a lighter brown, slightly broader and more flattened nut. It has been established that these specimens match the type of an Australian annual sp. (S. australiensis) in a number of characters, but the material is rather meagre for a firm decision.