Flora of New Zealand Series

Original localities: "Canterbury—drains and streams running into the Selwyn. In a small stream near the outlet of L. Ellesmere. T. Kirk. Otago—Waihola Lake, D. Petrie." Kirk's and Petrie's collections are both represented at AK and at WELT.

Submerged summer-green herb. Rhizome to 1 mm. diam., internodes 1–2 cm. long. Stems occ. branched, to 20 cm. long, filiform; internodes c. 1–4 cm. long. Lvs regularly alt.; lf-base at first sheathing stem, to 4 mm. long, fibrous in age; lamina c. 2.5–3.5 cm. × 1 mm., 1-(or 3-) nerved, entire, tip squarely truncate, nerve (or nerves) shortly excurrent. Fl. enclosed within lf-bases. ♂ on pedicel that elongates to 5 mm.; per.-segs mucronate, enclosing only extreme base of anther; stamen solitary; anther 2 × 0.6 mm., sessile, curved; pollen sacs 2, connective excurrent in short, sharp mucro. ♀ shortly pedicellate; per.-segs narrow-oblong, ± laciniate, c. 1.5 × 0.5 mm.; carpels us. 3, occ. 4, shortly stipitate; style narrower than ovary, stigma obliquely funnel-shaped with long-fimbriate margins. Achene c. 1.5–2 × 0.5 mm., asymmetrically oblong, yellow, smooth, narrowing above to style-remnant c. 1 mm. long. 2n = 12.

DIST.: N., S., Ch.

Also recorded from Australia.

Fresh and ± brackish water.

FL. 11–5. FT. 12–5.

Kirk (loc. cit.) remarks: "The plant exhibits a departure from the usual characters of the genus—(1) In the large solitary anther which dehisces from the apex downwards, the cells diverging laterally; (2) in the produced connective; (3) in the reflexed and almost laciniate stigmas, which are very conspicuous." The N.Z. sp. would be at least as much at home in the genus Althenia Petit 1829, to which all 3 endemic Australian spp. have been attributed at one time or another.