''Populus'' × ''canescens'', the grey poplar, is a hybrid between ''

Populus alba ''Populus alba'', commonly called silver poplar,Webb, C. J.; Sykes, W. R.; Garnock-Jones, P. J. 1988: Flora of New Zealand. Vol. IV. Naturalised Pteridophytes, Gymnosperms, Dicotyledons. 4. Christchurch, New Zealand, Botany Division, D.S.I.R. si ...

'' (white poplar) and '' P. tremula'' (common aspen). It is intermediate between its parents, with a thin grey downy coating on the

leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

, which are much less deeply lobed than the leaves of ''P. alba''. It is a very vigorous tree with marked

hybrid vigour Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions o ...

, reaching tall and with a trunk diameter over much larger than either of its parents. Most trees in cultivation are male, but female trees occur naturally and some of these are also propagated.

Taxonomy

In 1789

William Aiton William Aiton (17312 February 1793) was a Scottish botanist. Aiton was born near Hamilton. Having been regularly trained to the profession of a gardener, he travelled to London in 1754, and became assistant to Philip Miller, then superinten ...

described the grey poplar as a

variety Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

of ''

'', ''P. alba'' var. ''canescens''. In 1804, James Edward Smith raised it to a full species, ''P. canescens''. He described differences between the leaves of the two taxa: ''P. alba'' has lobed leaves with snow-white ("''niveus''") undersides, whereas ''P. canescens'' has wavy-edged leaves with hoary ("''incanus''") undersides. Later authors sometimes noted the possibility that the grey poplar was a hybrid. It is now considered to be a hybrid between ''P. alba'' and '' P. tremula'', so the scientific name is written with the hybrid symbol.

References

{{DEFAULTSORT:Populus canescens canescens Plant nothospecies