Peruvian primrose

Ludwigia peruviana
Aquatic
Alternate
Simple
Yellow
Green

State Category: Schedule 1 - Prohibited
Biosecurity Queensland must be contacted within 24 hours 13 25 23.
Biosecurity Queensland Must attend site before any control measure is administered, advice will be provided to the land holder at this time.
A large long-lived wetland shrub much-branched stems usually growing 2-4 m tall its younger stems and leaves are hairy. Its alternately arranged leaves (5-12 cm long and 1-3 cm wide) have prominent veins. Its flowers (2-4 cm across) are borne singly and have four or five bright yellow petals and four or five persistent sepals. Its reddish or brownish fruit (10-25 mm long and 6-10 mm wide) are four-angled and hairy.

Common names 
Also known as: Peruvian primrose, Peruvian water primrose, ludwigia, Peruvian primrose bush, water primrose,
Family 
Onagraceae
Deciduous 
No
Flowering time 
Spring-Autumn
Native/Exotic 
Exotic
Origin 
Native to Mexico, Central America, the Caribbean and South America.
Notifiable 
Yes
State declaration 
Category 1
Council declaration 
As per State Declaration
Known distribution 

Locally naturalised in the coastal districts of central New South Wales. Also naturalised overseas in south-eastern India, Sri Lanka, Indonesia, south-eastern USA (i.e. Texas, Louisiana, Alabama, Florida, Georgia and North Carolina) and French Polynesia.

Habitat 

A potential weed of warmer temperate, sub-tropical and tropical regions that is usually found in wetlands, swamps, marshes and along the edges of lagoons and slow-moving waterways (sometimes also floating on the water surface).

Habit 

A large, long-lived (i.e. perennial), wetland shrub usually growing 2-3 m tall, but occasionally reaching up to 4 m in height. It loses its leaves during winter (i.e. it is deciduous) in cooler climates and sometimes also floats freely on the water surface.

Biosecurity Queensland Must attend site before any control measure is administered, advise will be provided to the land holder at this time

Peruvian primrose (Ludwigia peruviana) is regarded as an environmental weed in New South Wales and as a potential environmental weed or "sleeper weed" in many other parts of Australia. During a recent survey, it was listed as a priority environmental weed in at least one Natural Resource Management region. While currently relatively localised in central New South Wales, Peruvian primrose (Ludwigia peruviana) is thought to have the potential to become a major aquatic weed in eastern AustraliaPeruvian primrose (Ludwigia peruviana) is mainly naturalised around swampy lake margins in and around Sydney. This species has become dominant in the Botany Wetlands, replacing much of the former vegetation of this series of shallow urban swamps and lakes. It is also considered to be a threat to endangered freshwater wetlands throughout the Sydney Basin bioregion. In recent years the distribution of this species has begun to expand. It has been found in Hornsby Shire, in northern Sydney, and a few outbreaks have also been recorded along drainage channels, creeks, and near lagoons in the Gosford and Port Stephens areas in the New South Wales Central Coast region.This species forms dense, monotypic stands in shallow slowly-flowing waterways, as well as in marshy areas, riparian vegetation and around the margins of still waterbodies. Once established, it sprawls out into the water surface and can form floating islands of vegetation. Its tall dense growth excludes most other vegetation and reduces light levels reaching the water surface, eventually replacing native vegetation and reducing biodiversity in invaded areas. It also causes more wide-ranging ecological damage, through increased sedimentation and accumulation of organic material. This results in the deoxygenation of the water column and can lead to the death of aquatic animals.

Stem and leaves 

The stems are green or brownish-green in colour and are much-branched. Younger stems are usually rounded and hairy (i.e. pubescent). The leaves are alternately arranged, or rarely paired, and are stalkless (i.e. sessile) or borne on very short stalks (i.e. petioles). These leaves (5-12 cm long and 1-3 cm wide) have prominent veins and are covered in hairs (i.e. pubescent). They are generally egg-shaped in outline (i.e. ovate), oval (i.e. elliptic) or elongated in shape (i.e. lanceolate) with entire margins. Their have upper surfaces are usually darker green than their paler undersides.

Flowers and fruits 

The yellow flowers (2-4 cm across) are borne singly on stalks originating in the forks (i.e. axils) of the upper leaves. These flowers usually have four petals (1-3 cm long and 1-3 cm wide), but occasionally there are five or six petals present. They also have four large green sepals that are persistent and turn reddish in colour as the fruit begins to mature. Flowering occurs mostly during late summer and autumn. The reddish or brownish coloured fruit is an upright, four-angled, and slightly elongated capsule (10-25 mm long and 6-10 mm wide) containing large numbers of seeds (i.e. 1000-3000). These tiny seeds (0.6-0.8 mm long) are light brown in colour and almost rounded in shape (i.e. sub-globular).

Reproduction and dispersal 

This species reproduces by seed and also vegetatively via suckers from submerged stems or stem fragments.Seeds are dispersed mostly by water and birds, but also by wind, machinery and in mud. Stem fragments may be spread by floods, machinery or during removal.

Similar species 

Peruvian water primrose (Ludwigia peruviana) is similar to several closely related species including native willow primrose (Ludwigia octovalvis), long-leaved willow primrose (Ludwigia longifolia) and water primrose (Ludwigia peploides subsp. montevidensis). These species can be distinguished by the following differences: Peruvian water primrose (Ludwigia peruviana) is an upright (i.e. erect) shrub with rounded stems and leaves that are covered in hairs (i.e. pubescent). Its relatively broad leaves are generally egg-shaped in outline (i.e. ovate). Its flowers usually have four large yellow petals and its fruit (10-25 mm long) are hairy (i.e. pobescent) and four-angled in cross-section.long-leaved willow primrose (Ludwigia longifolia) is an upright (i.e. erect) woody herb or small shrub with four-angled stems and leaves that are hairless (i.e. glabrous). Its glossy leaves are elongated (i.e. lanceolate) or linear in shape. Its flowers usually have four large yellow petals and its fruit (10-35 mm long) are hairless (i.e. glabrous) and four-angled in cross-section.native willow primrose (Ludwigia octovalvis) is an upright (i.e. erect) woody herb or small shrub with rounded stems and leaves that are usually covered in hairs (i.e. pubescent). Its leaves are quite variable and can be egg-shaped in outline (i.e. ovate) to very elongated in shape (i.e. linear-lanceolate). Its flowers usually have four large yellow petals and its fruit (20-45 mm long) are hairy (i.e. pubescent) and rounded in cross-section.water primrose (Ludwigia peploides subsp. montevidensis) is a creeping (i.e. prostrate or decumbent) or floating plant with rounded stems and leaves that are mostly hairless (i.e. glabrous). Its glossy leaves can be egg-shaped in outline (i.e. ovate) to elongated (i.e. lanceolate) in shape. Its flowers usually have five yellow petals and its fruit (10-30 mm long) are mostly hairless (i.e. glabrous) and rounded in cross-section.