Classification
Class
Magnoliopsida Brongn.
Order
Alismatales R.Br. ex Bercht. & J.Presl
Family
Ruppiaceae Horan.
Genus
Ruppia L.
 Nomenclature
Scientific Name:
Ruppia polycarpa R.Mason, New Zealand J. Bot. 5: 524 (1967)
 Description

Rhizome either much branched and congested giving rise to short stems and long lvs in dense grass-like mats or less closely branched with longer, sparsely branched stems. Lvs c. 5–30 cm. × 0.3–0.4 mm., dark green, almost filiform and only slightly flattened; apex obtuse, often most minutely denticulate; sheath (1)–2.5–3.5–5 cm. long, auricles narrow. Peduncles to 50 cm. long, us. conspicuously thicker just below fls, becoming spirally coiled as fr. matures. Fls protandrous; carpels us. 8, occ. to 16, rarely < 5. Podogynes slender. Achenes (1.7)–2–(2.7) mm. long, asymmetric, brown; mesocarp thin; endocarp smooth, black, with 2 longitudinal slits opp. to and about on level of top of operculum; beak 0.2–0.3 mm. long. 2n = 18.

[From: Moore and Edgar (1970) Flora of New Zealand. Volume 2.]

 Biostatus
Indigenous (Non-endemic)
 Phenology

Flowering: Oct.–(Feb.); Fruiting: Oct.–May.

 Bibliography
de Lange, P.J.; Rolfe, J.R.; Barkla J.W.; Courtney, S.P.; Champion, P.D.; Perrie, L.R.; Beadel, S.N.; Ford, K.A.; Breitwieser, I.; Schönberger, I.; Hindmarsh-Walls, R.; Heenan, P.B.; Ladley, K. 2018: Conservation status of New Zealand indigenous vascular plants, 2017. New Zealand Threat Classification Series. No. 22. [Not Threatened]
de Lange, P.J.; Rolfe, J.R.; Champion, P.D.; Courtney, S.P.; Heenan, P.B.; Barkla, J.W.; Cameron, E.K.; Norton, D.A.; Hitchmough, R.A. 2013: Conservation status of New Zealand indigenous vascular plants, 2012. New Zealand Threat Classification Series 3. Department of Conservation, Wellington. [Not Threatened]
Mason, R. 1967: The species of Ruppia in New Zealand. New Zealand Journal of Botany 5(4): 519–531.