Scientific Name:
Myriophyllum triphyllum Orchard, Brunonia 2: 259 (1980)
Vernacular Name(s):
Water milfoil

Perennial herb; stems 50–100 cm long, weak, simple or branched. Lvs dimorphic, whorled. Submerged lvs in whorls of (2)–3–(4), ovate, subsessile, (6)–10–15 × (5)–7–10–(15) mm, pectinate; pinnae 12–18, filiform, c. 8 mm long. Aerial lvs red-purple, in whorls of 3–(4), narrowly ovate to obovate, (2.5)–5–6–(12) × (1.5)–2–2.5–(4) mm, usually entire (lower or transitional lvs sometimes incised), obtuse. Fls solitary in axils of the aerial lvs, unisexual, the upper ♂, the lower ♀. Bracteoles lanceolate, (1)–1.4–1.8–(2) × (0.2)–0.3–0.4 mm. ♂ fls: sepals 4, 0.5–0.6 × 0.4–0.5 mm, deltoid; petals 4, hooded, 2–2.8 × c. 2 mm. ♀ fls: sepals 4, c. 0.2 × 0.2 mm; petals 4, c. 0.5 mm long. Frs ± globular or cubiform, 1.3–1.4–(1.5) × 1.4–1.5 mm, smooth and rounded on dorsal surface of mericarps, sometimes with a faint dorsal line.

[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]

Indigenous (Endemic)
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]
Orchard, A.E. 1979: Myriophyllum (Haloragaceae) in Australasia. 1. New Zealand: a revision of the genus and a synopsis of the family. Brunonia 2: 247–287.