Plants of South Eastern New South Wales
Myriophyllum gracile
Common name
Slender Water-milfoil
Family
Haloragaceae
Where found
In shallow water or on mud. Greater Sydney area and north from there (both varieties).
Notes
Perennial herb to 0.2 m tall. Stems mostly about 1 mm in diameter, rooting mainly at the base. Leaves alternating along the stems, 0.5-1 cm long, either margins entire to toothed, or leaves divided into 3–7 segments. Male and female flowers usually on the same plant, sometimes male and female flowers on different plants. Male flowers with 4 hooded petals, creamy-yellow with a reddish tip, 2–2.5 mm long. Female flowers with 0 sepals, 0 petals, stigmas white. Flowers single at the bases of the leaves. Flowers mainly spring.
var. gracile: Leaves divided into usually 5 narrow segments, mostly 0.5–1 cm long. Male and female flowers usually on the same shoot, sometimes on separate shoots. Seed cases deep reddish brown, sparsely warty
var. lineare: Leaves mostly 0.5–0.8 cm long. Lower leaves often with short teeth; upper leaves entire. Male and female flowers on the same shoot or some shoots have females only. Seed cases yellow-brown to deep reddish brown, densely warty.
Endangered Vic (var. lineare). Listed in the Flora and Fauna Guarantee Act, Vic. (var. lineare).
Definite identification of species of Myriophyllum often requires microscopic examination of the seed cases, beyond the scope of this key.
PlantNET description of species and key to varieties: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Myriophyllum~gracile (accessed 24 January, 2021)
This identification key and fact sheets are available as a free mobile application:
