|Salix cinerea subsp. cinerea, Germany|
|Green: Salix cinerea subsp. cinerea
Orange: Salix cinerea subsp. oleifolia
It is a deciduous shrub or small tree growing to 4–15 m (13–49 ft) high. The leaves are spirally arranged, 2–9 cm long and 1–3 cm 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.
- S. c. cinerea - central and eastern Europe, western Asia, shrub to 4–6 m (rarely 10 m) tall, with smooth bark, leaves densely hairy below with pale yellow-grey hairs, stipules large, persistent until autumn
- S. c. oleifolia (Sm.) Macreight (syn. S. atrocinerea Brot.) - western Europe, northwest Africa, shrub or tree to 10–15 m tall, with furrowed bark, leaves thinly hairy below with dark red-brown hairs, stipules small, early deciduous
Some overlap in the distributions (not indicated in the map, right) occurs, with both occurring in a broad band north to south through France, and scattered specimens of S. c. cinerea west to Ireland, western France, and Morocco; scattered specimens of S. c. oleifolia occur east to the Netherlands. Specimens of S. c. oleifolia in southern Scandinavia are planted or naturalised, not native. Intermediate specimens also occur.
It usually grows in wetlands. The two subspecies differ slightly in requirements, with S. c. cinerea generally restricted to basic marshland and fen habitats, while S. c. oleifolia is less demanding, occurring in both alkaline marshes and acidic bogs and streamsides. 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.
- Meikle, R. D. (1984). Willows and Poplars of Great Britain and Ireland. BSBI Handbook No. 4. ISBN 0-901158-07-0.
- Christensen, K. I., & Nielsen, H. (1992). Rust-pil (Salix cinerea subsp. oleifolia) - en overset pil i Danmark og Skandinavien. Dansk Dendrologisk Årsskrift 10: 5-17.
- Kabir, Faisal MD; Moritz, Kim K; Stenberg, Johan A (2015-04-19). "Plant-sex-biased tritrophic interactions on dioecious willow". Ecosphere. doi:10.1890/ES14-00356.1.
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