The whitebeams are members of the family Rosaceae, tribe Malinae, comprising a number of deciduous Simple leaves or lobe-leaved species formerly lumped together within Sorbus Sensu lato Many whitebeams are the result of extensive intergeneric hybridisation involving the genera Sorbus ( Sorbus aucuparia in particular), Aria, Torminalis and Chamaemespilus. As an effect, they are commonly Apomixis (reproducing solely asexually) and many have very restricted ranges. The best known species is the common whitebeam ( Aria edulis), a columnar tree which grows to tall by broad, with clusters of white flowers in spring followed by speckled red berries in autumn (fall).
Appearance
In many species, the surface of the leaves is an unremarkable mid-green, but the underside is pale to almost white (hence the name) with pale grey or white
Trichome, transforming the appearance of the tree in strong winds, as noted by the poet
George Meredith: "flashing as in gusts the sudden-lighted whitebeam".
[ Meredith, G. (1851). Love in the valley. Line 207. Poems] It is also described as the "wind-beat whitebeam" in Gerard Manley Hopkins' poem "The Starlight Night".
[ Hopkins, Gerard Manley (1918). The starlight night. Line 6.]
Ecology
The berries are a favourite of fruit-eating birds like thrushes and
, though are less palatable (drier, less juicy) than rowan berries. Whitebeams are sometimes used as
food plants by species of
Lepidoptera, including the short-cloaked moth.
Uses
These trees are often grown in parks and large gardens. The
cultivars A. edulis 'Lutescens'
and
A. edulis 'Majestica' have gained the Royal Horticultural Society's Award of Garden Merit.
The tough, hard wood is a deep orange when wet, and pale yellow after drying.
The fruit is edible, but only when nearly rotten.
Taxonomy
Whitebeams are not a natural
monophyly taxonomic grouping; they are representatives of several genera of the
Malinae subtribe, all of which were traditionally treated within a broadly circumscribed genus
Sorbus Sensu lato This treatment of
Sorbus was however was found to be
polyphyly, comprising two monophyletic clades that were not particularly closely related to each other. Now,
Sorbus is more often defined in a narrow sense to include only the
or mountain-ashes, with all the other former members being elevated into genera in their own right. Species which are commonly referred to as whitebeams can be found in several genera, five of which are the result of intergeneric hybridisation.
Non-hybridogenous whitebeam genera
In western Eurasia
In eastern Eurasia
Hybridogenous whitebeam genera
