Sorbus forrestii McAll. & Gillham

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Credits

Article from New Trees, Ross Bayton & John Grimshaw

Recommended citation
'Sorbus forrestii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/sorbus/sorbus-forrestii/). Accessed 2020-09-25.

Genus

Glossary

apomict
Taxon that reproduces only or regularly by apomixis.
key
(of fruit) Vernacular English term for winged samaras (as in e.g. Acer Fraxinus Ulmus)
section
(sect.) Subdivision of a genus.
type specimen
A herbarium specimen cited in a taxonomic account to define a particular species or other taxon.

References

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Credits

Article from New Trees, Ross Bayton & John Grimshaw

Recommended citation
'Sorbus forrestii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/sorbus/sorbus-forrestii/). Accessed 2020-09-25.

Tree to 12 m, though usually less. Branchlets grey. Buds deep red, conical to ovoid with white hairs on the margins and apices of the scales. Leaves to 20 cm long, with seven to nine pairs of leaflets. Leaflets rather widely spaced, ~4 cm long, upper surface glabrous, lower surface highly papillose, margins dentate to entire; leaves turning salmon-pink to orange in autumn. Fruit white with a crimson tint at the calyx, 0.8 × 0.95 cm; carpels three to four (to five). Tetraploid apomict (2n = 68). McAllister & Gillham 1980, McAllister 2005a. Distribution CHINA: Yunnan (Beima Shan). Habitat Mixed thickets. USDA Hardiness Zone 6. Conservation status Not evaluated. Illustration McAllister & Gillham 1980, McAllister 2005a. Cross-reference S497.

Sorbus forrestii, although another apomictic member of section Discolores, does not resemble the familiar species S. glabriuscula and S. pseudohupehensis and therefore does not feature in the key to their allies (p. 804). It is distinct in its larger white fruits and smaller but more numerous leaflets. It is also smaller-growing in cultivation, and at Ness has reached only 4 m in 40 years (McAllister 2005a), though elsewhere it is faster. Like others, however, it was recognised in cultivation, when in 1972 it was drawn to Hugh McAllister’s attention under the name S. prattii. Research found it to be growing in several British botanical gardens, and a chain of evidence led to its identification with Forrest’s collection (no. 19583) made on the Beima Shan, Yunnan in 1921. The dense crops of white fruit and low bushy habit make it ideal for smaller sites, and it is now widely grown and commercially available throughout our area.

Much rarer, and as yet only tentatively distributed beyond Ness and Keith Rushforth’s own collection, is another apomict, S. bulleyana McAll., which differs principally in its more numerous leaflets (9–11 pairs) and ‘pearly pinkish white’ fruits. The solitary tree at Ness is derived from Keith Rushforth’s gathering KR 2809 made in 1993 in the Zhongdian Gorge, Yunnan at 3200 m, which also provided the type specimen. The specimen at Ness is a bit straggly, but the fruits are pretty. From the same seed collection came an anomalous diploid seedling that has been named ‘Keith Rushforth’ (McAllister 2005a).

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