Whitebeam

The whitebeams are members of the family Rosaceae, comprising subgenus Aria (or, according to some authorities, its own genus) of genus Sorbus, and hybrids involving species of this subgenus and members of subgenera Sorbus, Torminaria and Chamaemespilus. They are deciduous trees with simple or lobed leaves, arranged alternately. They are related to the rowans (Sorbus subgenus Sorbus), and many of the endemic restricted-range apomictic microspecies of whitebeam in Europe are thought to derive from hybrids between S. aria and the European rowan S. aucuparia; some are also thought to be hybrids with the wild service tree S. torminalis, notably the service tree of Fontainebleau Sorbus latifolia in French woodlands.

Whitebeam
Common whitebeam flowers
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Rosaceae
Genus: Sorbus
Subgenus: Sorbus subg. Aria
Pers.

The best known species is the common whitebeam Sorbus aria, a columnar tree which grows to 25 m (82 ft) tall by 10 m (33 ft) broad, with clusters of white flowers in spring followed by speckled red berries in autumn (fall).[1]

Appearance

The surface of the leaf is an unremarkable mid-green, but the underside is almost white (hence the name) transforming the appearance of the tree in strong winds, as noted by the poet Meredith: "flashing as in gusts the sudden-lighted whitebeam".[2] It is also described as the "wind-beat whitebeam" in Gerard Manley Hopkins' poem "The Starlight Night".[3]

Ecology

The berries are a favourite of birds, though less palatable (drier, less juicy) than rowan berries. Whitebeams are sometimes used as larval food plants by Lepidoptera species, including the short-cloaked moth.

Uses
Cross-section of a whitebeam trunk

These trees are often grown in parks and large gardens. The cultivars S. aria 'Lutescens'[4] and S. aria 'Majestica' have gained the Royal Horticultural Society's Award of Garden Merit.[5]

The tough, hard wood is a deep orange when wet, and pale yellow after drying.

The berries are edible and are often made into jelly.

Classification
  • section Aria - Sorbus aria and its close relatives
  • section Alnifoliae - a group of Asian species
  • section Thibeticae - a group of species from the Himalayas and southern China
  • Sorbus intermedia group (nothosubgenus Soraria) - taxa of hybrid origin involving sections Aria and Sorbus
  • Sorbus latifolia group (nothosubgenus Tormaria) - taxa of hybrid origin involving sections Aria and Torminaria

Selected species

Sorbus subgenus Aria

Plus many other species

References
  1. RHS A-Z encyclopedia of garden plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 978-1405332965.
  2. Meredith, G. (1851). Love in the valley. Line 207. Poems
  3. Hopkins, Gerar Manley (1918). The starlight night. Line 6.
  4. "RHS Plant Selector - Sorbus aria 'Lutescens'". Retrieved 4 June 2013.
  5. "RHS Plant Selector - Sorbus aria 'Majestica'". Retrieved 4 June 2013.
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