Mountain Ash

sorbus, mountain ash

UBC Botanical Garden has an extensive and diverse collection of Sorbus species. Sorbus is a member of the rose family (Rosaceae) in the group that includes apples, pears and hawthorns. The genus Sorbus comprises about 120 species of small trees native to mountains and moister regions of the Northern Hemisphere. Nearly all of the species have deciduous leaves and showy white, but somewhat malodorous flowers that appear in April or May, followed by colourful fruits (technically, pomes—like little apples) in summer. Autumn colour is often outstanding, especially when trees are grown in the open. Fruits may be pink, white, yellow, orange or red.

Sorbus species include trees and shrubs with either pinnately compound leaves or simple leaves, though there are naturally occurring hybrids that are intermediate between the two types. The pinnate-leafed species are generally called rowans in Britain, but elsewhere they are known as mountain ashes. The simple-leafed sorbi, the whitebeams, are sometimes classified in their own genus, Aria (here, they are listed under the subgenus Aria). Like the closely related cotoneasters and hawthorns, many Sorbus species are apomictic “microspecies.” These are populations that reproduce by seed but without fertilization and that are genetically uniform, and different than populations of related, similar looking, sexually reproducing individuals. One of the horticultural implications of apomixis is that seedlings are essentially clones (they are genetically identical). Sexual species, on the other hand, produce offspring that can vary considerably, one to the next. The Garden’s collections number nearly 80 taxa.

 Subgenus Aria (whitebeams)

  • Sorbus alnifolia
  • Sorbus aronioides
  • Sorbus arranensis
  • Sorbus caloneura
  • Sorbus chamaemespilus
  • Sorbus coronata
  • Sorbus folgneri
  • Sorbus glomerulata
  • Sorbus hemsleyi
  • Sorbus henryi
  • Sorbus karchungii
  • Sorbus keissleri
  • Sorbus lanata
  • Sorbus megalocarpa
  • Sorbus meliosmifolia
  • Sorbus pallescens
  • Sorbus rhamnoides
  • Sorbus sudetica
  • Sorbus thibetica
  • Sorbus thomsonii
  • Sorbus yuana
  • Sorbus zahlbruckneri
  • Sorbus CGG.14008
  • Sorbus DGEY.230
  • Sorbus H&M.2209
  • Sorbus N.100
  • Sorbus PW.0042
  • Sorbus PW.0107
  • Sorbus PW.0112
  • Sorbus PW.0133
  • Sorbus WWJ.11709

Subgenus Sorbus (mountain ashes)

  • Sorbus americana
  • Sorbus aucuparia
  • Sorbus cashmiriana
  • Sorbus commixta
  • Sorbus decora
  • Sorbus discolor
  • Sorbus foliolosa
  • Sorbus forrestii
  • Sorbus glabriuscula
  • Sorbus gracilis
  • Sorbus harrowiana
  • Sorbus koehneana
  • Sorbus macrantha
  • Sorbus matsumurana
  • Sorbus monbeigii
  • Sorbus multijuga
  • Sorbus pohuashanensis
  • Sorbus poteriifolia
  • Sorbus prattii
  • Sorbus pseudohupehensis
  • Sorbus pseudovilmorinii
  • Sorbus reducta
  • Sorbus rehderiana
  • Sorbus rosea
  • Sorbus sargentiana
  • Sorbus setschwanensis
  • Sorbus sitchensis sitchensis
  • Sorbus sitchensis grayi
  • Sorbus ursina
  • Sorbus verrucosa subulata
  • Sorbus vilmorinii
  • Sorbus wilsoniana
  • Sorbus BCHM.090
  • Sorbus BCHM.119
  • Sorbus BHMWZ.021
  • Sorbus BHMWZ.022
  • Sorbus BHMWZ.081
  • Sorbus PW0113
  • Sorbus SEH.152
  • Sorbus SICH.0828
  • Sorbus YU.13815
  • Sorbus YU.14299

Cultivars and Selections

  • Sorbus alnifolia ‘Skyline’
  • Sorbus commixta ‘Serotina’
  • Sorbus ‘Ghose’
  • Sorbus ´ hybrida ‘Gibbsii’
  • Sorbus ´ intermedia
  • Sorbus ‘John Mitchell’
  • Sorbus ‘Joseph Rock’