bio.wikisort.org - Plant

Sorbus rupicola, known as rock whitebeam,[1] is a rare shrub or small tree best known from the British Isles but also reported from Norway, Sweden and Russia.[2]

Sorbus rupicola
Rock whitebeam at the Trondheimsfjord, Norway
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Rosales
Family:	Rosaceae
Genus:	Sorbus
Subgenus:	Sorbus subg. Aria
Species:	S. rupicola
Binomial name
Sorbus rupicola (Syme) Hedl.

Reaching heights of 10 m,[3] it grows in rocky woodland, scrub and cliffs, usually on limestone.[3]

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).

Sorbus rupicola is a member of Sorbus aria agg., which contains 20 subspecies. A key to this aggregate is given in Stace - though be warned Stace states "It is probably impossible to construct a reliable key to the agg."![3] Stace gives Sorbus 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.

• 
  A young specimen
• 
  Back of a leaf
• 
  Upper surface of a leaf
• 
  Upper surface of a leaf
• 
  Twig and part of a leaf

References

Further reading

• Ennos, R. A.; G. C. French; P. M. Hollingsworth (2005). "Conserving taxonomic complexity". Trends in Ecology and Evolution. 20 (4): 164–168. doi:10.1016/j.tree.2005.01.012. PMID 16701363.
• Robertson, A.; A. C. Newton; R. A. Ennos (2004). "Multiple hybrid origins, genetic diversity and population genetic structure of two endemic Sorbus taxa on the Isle of Arran, Scotland". Molecular Ecology. 13 (1): 123–134. doi:10.1046/j.1365-294X.2003.02025.x. PMID 14653794. S2CID 38956138.

External links

• Distribution map of S. rupicola. Naturhistoriska riksmuseet.

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