Plants of South Eastern New South Wales

Myriophyllum caput-medusae

Leafy stems. Photographer Euan Moore, Murray River

Line drawings. Illustration: G. Thomlinson, i. branch (with submerged and emergent leaves); seed case. National Herbarium of Victoria, © 2021 Royal Botanic Gardens Board

Common name

Cat-tail, Coarse Water-milfoil

Family

Haloragaceae

Where found

Aquatic. In lakes, and backwaters of slowly moving watercourses. Ranges, tablelands, and Western Slopes.

Notes

Perennial herb, stems  to 2 m long, usually 3–4 mm in diameter, rooting mainly at the base. Parts of the plants above the water much-branched. Emergent leaves in whorls of 3–5 just above the water, alternating up the stems towards the tips of the stems, mostly 0.6–1 cm long, up to 3 mm wide, glaucous, more or less red-tipped to purplish, margins entire. Submerged leaves in whorls of 3–5, mostly 1.2–2 cm long, compound, with 16–20 narrow segments like the teeth of a comb. Male and female flowers on the same stem. Male flowers with 4 yellow to reddish hooded petals 2.1–2.6 mm long. Female flowers with 0 sepals, 0 petals, stigmas reddish. Flowers single at the base of whorled leaves.

Definite identification of species of Myriophyllum often requires microscopic examination of the seed cases, beyond the scope of this key.

PlantNET description:  http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Myriophyllum~caput-medusae (accessed 24 January, 2021)