willows
The term 'willow' refers to several different tree and shrub species, including weeping willow. Willow species are Weeds of National Significance (WONS). They can invade riverbanks and wetlands, causing erosion and blocking waterways. Willows are a serious weed in Victoria, New South Wales and the Australian Capital Territory, causing millions of dollars in damage. Smaller numbers are also found in southern Queensland.
Wide spread in the southern states, prefers tempeate climate, limited establishment around Stanthorpe, Towoomba. And southern Queenslands more temperate areas.
Prefers wet or moist soils, riparian zones can tolerate dryer soils but will loose leaves during dry periods
Willows are deciduous trees or shrubs. They have small seeds with long, silky hairs attached to one end like a parachute, which help them spread. The seeds are usually short-lived, from days to a few weeks.
Unlike most other vegetation, willows spread their roots into the bed of a watercourse, slowing the flow of water and reducing aeration. They form thickets which divert water outside the main watercourse or channel, causing flooding and erosion where the creek banks are vulnerable. Willow leaves create a flush of organic matter when they drop in autumn, reducing water quality and available oxygen, and directly threatening aquatic plants and animals. This, together with the amount of water willows use, damages stream health.
Stems and leves vary widely across the approximate 400 species
Most willows have either male or femeale plants although some may have both male and female flowers on the same plant the flowers of a willow are referred to as catkins which are Elongated cluster of single-sex flowers bearing scaly bracts and usually lacking petals.
Most willows spread by fragments of stems or twigs breaking off and growing new roots in water. Pieces can travel many kilometres before establishing at a new site. Fishermen often break off twigs and stick them in the riverbank to hold their lines, and these pieces will also grow. Seed is the main method of spread for several species, especially grey sallow and black willow. These species can invade off-stream wetlands from sea level to alpine locations.
Approximately 400 species within the salix genus which have varying growth forms
