Eichhornia crassipes infestation2
Introduced, warm-season, perennial, erect, emergent, free-floating, stoloniferous aquatic herb to 1 m tall. Roots are black to purple, feathery and to 1 m long. Stolons root at nodes to form daughter plants. Leaves are all basal; the petiole is spongy, often inflated and buoyant; the blade is flat, circular to ovate, to 25 cm diam., apiculate, with numerous longitudinal veins; margins are gently incurved and often slightly undulate. Flowerheads are axillary spike-like to paniculate and slightly exceeding the leaves. Flowers are 3–6 cm in diam. There are 6 blue perianth lobes 3–4 cm long; fused below and upper lobe has a darker blue patch with a yellow centre. Stamens 6, 3 longer almost exerted, 3 shorter. Flowering is during the warmer months. It is one of the world’s worst weeds due to its ability to rapidly cover whole waterways. In Australia, it forms dense, impenetrable mats invading native wetlands and eliminating native aquatic plants. Water hyacinth blocks irrigation channels and reduces the aesthetic value of waterways. It restricts livestock access to and recreational use of waterways. Flood stranded water hyacinth can destroy fences, roads and infrastructure. It was brought to Australia as an ornamental plant in the 1890s and now occurs in coastal waterways from Kiama in NSW to southern Cape York Peninsular in Queensland.