Salix cinerea

It is a deciduous shrub or small tree growing 4–10 metres (13–30 ft) tall. The leaves are spirally arranged, 2–9 cm (1– in) long and 1–3 cm (– in) broad (exceptionally up to 16 cm long and 5 cm broad), green above, hairy below, with a crenate margin. The flowers are produced in early spring in catkins 2–5 cm long; it is dioecious with male and female catkins on separate plants. The male catkins are silvery at first, turning yellow when the pollen is released; the female catkins are greenish grey, maturing in early summer to release the numerous tiny seeds embedded in white cottony down which assists wind dispersal. ==Taxonomy==

The closely related species Salix atrocinerea Brot., which overlaps in distribution in France, Belgium, Netherlands, England and Ireland, is considered by some authors as the subspecies S. cinerea oleifolia (Gaudin) Macreight. S. atrocinerea differs from S. cinerea in that it is taller (reaching up to 15 metres), has a deeply furrowed bark, dark red-brown hairs beneath the leaves, smaller stipules, and is earlier deciduous. ==Ecology==

Grey willow grows in wetlands, moist depressions, ditches, embankments, banks of stagnant or slow-moving water bodies, and forest edges, where it encounters low-lying damp situations with waterlogged and nutrient-poor soils. S. cinerea is a pioneer species that rapidly colonizes disturbed sites. A common herbivore of Salix cinerea is Phratora vulgatissima, which prefers and is more common on female plants. Anthocoris nemorum, a natural enemy of Phratora vulgatissima, is also more common on S. cinerea. ==Invasive species==

Salix cinerea is an invasive species in New Zealand and is listed on the National Pest Plant Accord, which means it cannot be sold or distributed. S. cinerea is also highly invasive in south-eastern Australia, with the entire genus listed as a Weed of National Significance. The species was introduced to stop erosion along riverbanks, but has since caused worse erosion over time by widening and shallowing invaded streams. ==References==