Longleaf Primrose-Willow

Appearance

They are alternately arranged along the stems, mostly hairless, and have a
somewhat glossy appearance. The central vein of the leaf is prominent and often reddish in colour,
as are the younger stems.

The bright yellow flowers are borne singly in the upper leaf forks on stalks 5-40 mm long. Each
flower has four greenish or reddish sepals (1-2 cm long) with pointed tips. These sepals remain on
the fruit as it develops. Each flower also has four, or rarely five, bright yellow petals (20-25 mm long
and about 20 mm wide) with rounded tips. The fruit capsule is elongated in shape (1-4 cm long and
5-10 mm wide) and sharply four-angled. It contains large numbers of tiny dust-like seeds (less than
1 mm long) in four internal compartments. The fruit turn from green (or reddish) to light brown in
colour as they mature, and eventually split open or disintegrate to release their seeds.

Naming

Ludwigia longifolia (DC.) H. Hara
Jussiaea longifolia DC.

Distribution

Native range: Southern Brazil, Paraguay, Uruguay, and northern Argentina. Introduced in Australia (central and northern New South Wales and in south-eastern Queensland.) and the USA (Florida). Outside of its native range Ludwigia longifolia is regarded as an invasive species.

Reproduction

This species generally reproduces by seed, though stem segments may take root in suitable
conditions. The small seeds can be dispersed by water, wind, animals or human activities (e.g. in
contaminated soil or dumped garden waste). Seed production occurs throughout the year, but
is most abundant during summer and autumn.