Not tolerant of drought, the Australian hybrid willow establishes and grows quickly in any fertile soil that is close to a source of moisture. It is easily misidentified as other non-weeping willow tree species, and it creates seedlings with an ambiguous blend of parent tree characteristics. It reputedly grows successfully in USDA hardiness zones 5 through 9, although winter cold and high winds can be problematic.
The New Zealand Department of Science and Industrial Research created this tree by genetically crossing the white willow (Salix alba) with weeping willow (Salix matsudana). Nine clones, all believed to be male, were released over three decades in the latter 20th century and imported into Australia for use as windbreaks. Australians call this tree "New Zealand hybrid willow" while North Americans know it as the "Australian hybrid willow" or by the trademark name Austree.
Fast-growing, Australian hybrid willow becomes an upright plant that matures at 40 to 70 feet tall and no more than 15 to 20 feet wide. It develops a shallow, wide-reaching root system that benefits when moist soil pockets are encountered.
This deciduous tree's bark is fissured and grayish brown. The lance-like leaves are light green to pale bluish green. No branches weep, and the tree has a noticeable "tip" at the top, according to the Colorado State University Extension Service. Long white and pale yellow catkins (tiny flower clusters that look like elongated caterpillars) occur in early spring as the new leaves emerge. These catkins comprise either all male or all female blossoms. Any Australian hybrid willow tree marketed the Austree name is supposed to be an all male-flowering clone.
Australian hybrid willow's fast growth rate makes it a theoretical excellent choice to create a windbreak or shelterbelt in open landscapes as well as erosion control or noise and dust abatement. Overall it is not an attractive tree suitable for garden use. It provides light shade or wildlife cover/habitat in areas where the soil is moist to soggy.
According to the National Weeds Strategy of Australia and the New South Wales Flora Online, Australian hybrid willow is regarded as a noxious weed in southeastern Australia. It readily hybridizes with other willow species and spreads its seeds in the wind and then germinates reliably in moist soils. Any twig segment also potentially roots and develops into a new plant if left in contact with warm moist soil. The Colorado State University Extension Service says the tree is rather short-lived, weak wooded and in dry soils quickly succumbs to fungal cankers and often suffers branch die-back from cold winters.