Weed Identification

Australia > > Longleaf Ludwigia

Longleaf Ludwigia

Ludwigia longifolia

Alternative Name(s): Longleaf primrose willow

Family: Onagraceae

Form: Water plant

Origin: Native of Argentina, Brazil, Paraguay and Uruguay.

Flowers/Seedhead: Solitary. Open for 1 day and are produced in succession in leaf axils at the ends of stems.

Description: Erect annual herb to 2.5 m high. Roots fibrous, shallow. Stems branched, upper stems 4-angled and winged. Leaves alternate, ovate to lanceolate, 5–35 cm long, 0.5–2.5 cm wide. Capsule with seeds in each closed cavity in several rows, opening irregularly at maturity to release seeds. Seeds numerous, 0.5–0.8 mm long, 0.2–0.3 mm wide, oblong, straight to curved, brown to yellow.

Distinguishing features: Distinguished by erect habit; stems and leaves hairless; flowers with 4 (or 5) yellow petals 2–2.5 cm long, sepals 4 (or 5), stamens twice as many as sepals; capsule 4 (or 5) -angled 1–3.5 (rarely to 4) cm long, 0.4–0.8 cm wide; seeds not embedded in innermost wall of fruit.

Dispersal: Spread by seed.

Confused With: Other Ludwigia species, see taxonomic texts for detailed distinguishing features.


Narrow leaves, capsules and flower
Botany Wetlands, Jan

Notes: Introduced as an aquatic ornamental. Naturalised in swamps and marshes in New South Wales around Sydney, Gosford and Port Stephens and in Queensland around Brisbane. Longleaf Ludwigia displaces native species.

References:

    Flora of NSW. G. Harden (ed), Vol. 2, 2nd edition, 2002, page 237.

Web References: Search Australian web sites for further information on this weed.

Distinctive 4-angled hairless capsules
Botany Wetlands, Jan.

This weed has been included in the WEEDeck field guide as card W19

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.

 

Australia > > Longleaf Ludwigia

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