Aria rupicola explained

Aria rupicola, commonly known as rock whitebeam, is a rare species of shrub or small tree best known from the British Isles but also reported from Norway, Sweden and Russia.^[1]

Reaching heights of 10 m,^[2] it grows in rocky woodland, scrub and cliffs, usually on limestone.^[2]

The species reproduces apomictically (asexually via cloned seeds) and was presumably created by autopolyploidysation of the common whitebeam proper (Sorbus aria s.str.). It contains a tetraploidal set of chromosomes (2n=4x=68).

Stace gives Aria rupicola the following characteristics:

• Leaves unlobed or lobed ≤1/20 of the way to the midrib.
• Leaves with a single style of teeth or, weakly, two styles of teeth.
• Leaves with 6 to 9 (rarely 4 to 10) pairs of lateral veins.
• Leaves mostly 1.6 to 2.4 times longer than wide.
• Leaves mostly widest in that half of the leaf furthest from the stalk.
• Leaves usually obtuse (rarely acute) at apex.
• Leaves have dense white hairs on lower surface.
• Fruits 10-15mm across, warty.

Further reading

• Ennos, R. A. . G. C. French . P. M. Hollingsworth . Conserving taxonomic complexity . . 20 . 2005 . 16701363. 4. 164–168. 10.1016/j.tree.2005.01.012.
• 10.1046/j.1365-294X.2003.02025.x. Robertson, A. . A. C. Newton . R. A. Ennos . Multiple hybrid origins, genetic diversity and population genetic structure of two endemic Sorbus taxa on the Isle of Arran, Scotland . . 13 . 2004 . 123–134 . 14653794. 1. 38956138 .

External links

• Distribution map of S. rupicola. Naturhistoriska riksmuseet.

Notes and References

1. Web site: Ecological flora of the British Isles: Sorbus rupicola. 2010-07-17.
2. New Flora of the British Isles; Clive Stace; Third edition; 2011 printing