Plants of South Eastern New South Wales

Myriophyllum simulans

Leafy stems with flowers. Photographer Jackie Miles

Leaves with male flowers above, female flowers below. Photographer Don Wood, Namadgi National Park, ACT

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

Common name

Amphibious water milfoil

Family

Haloragaceae

Where found

Aquatic or in mud. Coast and tablelands. Occasional elsewhere.

Notes

Perennial herb to 0.4 m tall, rooting at the nodes. Emergent stems to 8 cm. long. Stems hairless. Emergent leaves in whorls of 3-5 or irregularly arranged, 0.5-1.5 cm long, to 2 mm wide (wider in divided leaves), linear to cylindrical, entire. Submerged leaves in whorls of 4 or 5, 1.8-2.5 cm long, dissected into 16-27 fine segments like the teeth of a comb. In terrestrial plants all leaves are intermediate between these two forms. Male and female flowers on the same plant. Male flowers with 4 reddish hooded petals 2.5-3 mm long, which fall off easily. Female flowers small with 0 sepals, 0 petals, red or pink stigmas, fading to white, ovaries a deep reddish purple. Flowers single at the base of whorled leaves. Flowers Sep.–Mar. 

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~simulans (accessed 24 January, 2021)