Long-leaf willow primrose

Long-leaf willow primrose is an invasive aquatic plant from South America which forms dense colonies in slow-moving and static waterways. It was first introduced to Australia as an ornamental plant, and has invaded wetlands and riparian areas near Sydney, on the Central Coast of NSW and near Brisbane, in Queensland. If no control action is taken it will dominate temperate and tropical wetland and riparian systems throughout Australia, according to the NSW Department of Primary Industries. Long-leaf willow primrose is a Class 2 noxious weed across the North Coast, except for the Nambucca local-government area where it is Class 1. […]

Cabomba

Cabomba is a submerged aquatic weed that has great potential to spread in New South Wales. The plant is fully submerged, except for occasional floating leaves and flowers above the water surface. The roots grow on the bottom of water bodies and the stems can reach the surface. Parts of the plant can survive free-floating for six weeks to eight weeks. Cabomba was introduced into Australia as an aquarium plant and was first recorded as naturalised in 1967. It is now a serious threat to Australian waterways and is a Weed of National Significance. Cabomba occurs in several locations in […]

 

Water hyacinth

Water hyacinth is a free-floating perennial water weed which reproduces from seeds and horizontal stems. It forms large, dense rafts on the water surface up to 65 cm tall. Roots are feathery, black to purple, growing to one metre long, but are usually short if the water is nutrient rich. Seeds are ovate-oblong, ribbed, about 1mm long. Erect stems, up to about 60 cm long, bear flowers and horizontal vegetative stems about 10 cm long, which produce new daughter plants. Young plants have leaf stalks up to 25 cm long which are inflated at the base and older plants have […]

kidney leaf mud plantain above surface 

Kidney leaf mud plantain

Kidney leaf mud plantain is an aquatic plant native to North, Central and South America. It grows well in disturbed shallow freshwater habitats. It was introduced into Australia as a pond pant, with escaped plants colonising freshwater streams ponds and mudflats. Kidney leaf mud plantain (KLMP) is not a declared Noxious Weed in NSW, however declaration is being considered as a Category 1 weed. It is 20-50 cm tall and can form thick colonies which usually emerge 10-30 cm, but can be up to 50 cm, above the water’s surface. The leaves are bright glossy green, kidney shaped (1-4cm long, […]

 

Salvinia

Salvinia is an aquatic fern with most leaves floating on the water surface, forming mat-like growths. Stems are 30 cm long, 1 mm to 2 mm thick, with multiple branches. Length decreases with increasing plant density. Leaves of isolated plants are oval to heart-shaped, flat and as small as 10 mm by 5 mm. The floating leaves are green, non-wettable on the upper surface and have complex waxy hairs about 1 mm long. The submerged modified leaves, which act like roots, are short brown hairy stalks ending in hairy filaments up to 50 cm long which look like wet hair. […]

hymenachne close-up 

Hymenachne

Hymenachne  is a semi-aquatic perennial grass that has become a major weed of wetlands, flood plains and sugar cane crops of northern Australia. Originally introduced to Queensland and the Northern Territory as a ponded pasture species, it has invaded freshwater wetlands, flood plains and river banks. It forms dense infestations, displaces native plant species, reduces biodiversity and threatens native wetland habitat. Native to the tropics of South and Central America, it is a serious weed in Australia, the West Indies, Indonesia, the Florida wetlands of USA and Suriname. Once considered a source of dry season fodder for cattle, it has […]

water lettuce on lagoon 

Water lettuce

Water lettuce is a perennial stoloniferous aquatic herb growing to 20 cm above water level with feathery roots. Leaves are wedge-shaped, pale green, buoyant towards base, to 15 cm long and to 8 cm wide. Flowers are small and partly concealed at the base of the plant. Flowers occur on a column surrounded by a whitish slit funnel-shaped bract (spathe). A large number of unbranched feathery roots up to 80 cm long are submersed in water beneath the leaves of the plant. Water lettuce is dispersed by seed and vegetatively by daughter plants at the end of stolons. Seeds, seedlings […]

alligator weed infestation 

Alligator weed

Alligator weed is a perennial herb. There are different forms of this plant which grow on land and in water. Aquatic forms may be free-floating, or rooted and emergent from the water surface. Stems are hollow. The horizontal stem that produces roots and has shoots that develop into new plants, forming dense interwoven mats. Severe frosts may kill exposed stems. Leaves are without stalks, dark green, smooth, waxy, 2-7 cm long, 5-40 mm wide, in pairs opposite each other on the main stems. Veins from the central rib are visible beneath the waxy leaf surface. Flowers have silvery white heads […]