Sorbus

Taxobox
name = "Sorbus"

---

image_width = 240px
image_caption = European Rowan ("Sorbus aucuparia") with fruit
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Rosales
familia = Rosaceae
subfamilia = Maloideae
genus = "Sorbus"
genus_authority = L.
subdivision_ranks = Subgenera
subdivision =
"Sorbus"
"Aria"
"Micromeles"
"Cormus"
"Torminaria"
"Chamaemespilus"

The genus "Sorbus" is a genus of about 100–200 species of trees and shrubs in the subfamily Maloideae of the Rose family Rosaceae. The exact number of species is disputed considerably between different authorities, due to the number of apomictic microspecies, treated by some as distinct species, by others grouped in a much smaller number of variable species, and also depending on the circumscription of the genus. Recent treatments (Robertson "et al." 1991, McAllister 2005) treat "Sorbus" in a narrower sense to include only the pinnate-leaved species of subgenus "Sorbus", raising several of the other subgenera to generic rank. Species of "Sorbus" (s.l.) are commonly known as whitebeam, rowan, service tree, and mountain ash.

As treated in its broad sense, the genus is divided into two main and three or four small subgenera (with more recent generic assignments in parentheses):

*"Sorbus" subgenus "Sorbus" (genus "Sorbus" s.s.), commonly known as the rowan (primarily in the UK) or mountain ash (in both North America and the UK), with compound leaves usually hairless or thinly hairy below; fruit carpels not fused; type species "Sorbus aucuparia" (European rowan). Distribution: cool-temperate Northern Hemisphere. (Genus "Sorbus" s.s.)

*"Sorbus" subgenus "Aria" (genus "Aria"), the whitebeam, with simple leaves usually strongly white-hairy below (hence the name, from German "Weissbaum", 'white tree'); fruit carpels not fused; type species "Sorbus aria" (common whitebeam). Distribution: temperate Europe & Asia.

:*"Sorbus" subgenus "Micromeles" (genus "Aria"), an indistinct group of a few east Asian species (e.g. "Sorbus alnifolia", Korean whitebeam) with narrow leaves; doubtfully distinct from and often included in subgenus "Aria". Distribution: temperate northeast Asia.

*"Sorbus" subgenus "Cormus" (genus "Cormus"), with compound leaves similar to subgenus "Sorbus", but with distinct fused carpels in the fruit; just one species, "Sorbus domestica" (True Service Tree). Distribution: North Africa, warm-temperate Europe, West Asia.

*"Sorbus" subgenus "Torminaria" (genus "Torminaria"), with rather maple-like lobed leaves with "pointed" lobes; fruit carpels not fused; just one species, "Sorbus torminalis" (Wild Service Tree). Distribution: temperate Europe, south to the mountains of North Africa and east to the Caucasus ranges.

*"Sorbus" subgenus "Chamaemespilus" (genus "Chamaemespilus"), a single shrubby species "Sorbus chamaemespilus" (false medlar) with simple, glabrous leaves and pink flowers with erect sepals and petals. Distribution: mountains of southern Europe.

*Hybrids are common in the genus, including many between the subgenera; very often these hybrids are apomictic (self-fertile without pollination), so able to reproduce clonally from seed without any variation. This has led to a very large number of microspecies, particularly in western Europe (including Britain) and parts of China.

"Sorbus" species are used as food plants by the larvae of some Lepidoptera species—see list of Lepidoptera that feed on Sorbus.

Wine

Sorbus is also a strong Finnish fruit wine spiced with Sorbus berries.

References

* McAllister, H. 2005. The Genus "Sorbus": Mountain Ash and Other Rowans. Richmond, Surrey, UK: Royal Botanic Gardens, Kew.
* Robertson, K. R., J. B. Phipps, J. R. Rohrer, and P. G. Smith. 1991. A Synopsis of Genera in Maloideae (Rosaceae). "Systematic Botany" 16: 376–394.

Further reading

* Price, D.T. 2007. One-way introgressive hybridisation between "Sorbus aria" and "S. torminalis" (Rosaceae) in southern Britain. "Watsonia." 26: 419–431.