Arrowhead plant

Sagittaria montevidensis

Description
Mainly emergent to 1 m tall.
Leaves:
Adult leaves: strongly arrow-shaped, to 25cm long
Submerged juvenile leaves: strap-like
Flowers:
■ 3 white petals, 2.5 cm diameter
■ 2–12 whorls of flowers at apex of a leafless
stem
■ Whorls of male flowers situated above
female flowers
■ Summer
Seeds:
■ Laterally flattened, 0.15–0.3 cm long with
wings
Similar species
■ Sagittaria (Sagittariagraminea ssp.
platyphylla): spear-shaped leaves
■ Juvenile leaves similar to Vallisneria spp.,
Ottelia ovalifolia, Alisma plantago-aquatica
■ #Water plantain (Alisma plantago-aquatica):
flowers on long stems and leaves rounder
at base
Background
Arrowhead is native to South America and is a common weed of rice in Australia. It grows
in warm-temperate, shallow, stationary or slow-moving water and can obstruct drainage
channels and compete with rice crops.
Distribution
Primarily found in rice-growing areas of southwestern NSW. Has also been found in a number
of waterways in Vic.
Means of spread
Arrowhead reproduces by seed, which is spread
by water and attaches to the hooves and fur of
animals.
Declaration status
NSW: C5(S); SA: 1@; WA: P1/2; Tas: D
If found, report this weed to your local weed
authority.


Source: Recognising Water Weeds Plant Identification Guide
Aquatic Weeds Early Detection Project Compiled by Jessica Grantley, Fiona McPherson and
Andrew Petroeschevsky,

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