Trees Gallery - The Yorkshire Arboretum -page 12

Sorbus oliveacea

Olive-fruited whitebeam

A native of China, collected from the mountains of Sichuan in 1992, this is a small deciduous tree growing to 10m. The pinnate leaves are a soft, pale grey-green, which add to its attraction as an ornamental plant.

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Sorbus pseudofennica

Arran service tree

A complex hybrid found wild only on the Isle of Arran, growing in Glen Catacol where they were first found in 1797. Classified as critically endangered by the IUCN International Union for Conservation of Nature . Where rowans and whitebeams meet hybrids often occur, sometimes these become stabilised as new species (often called microspecies) breeding true from seed through self fertilisation, a process known as apomixis. This species arose from pollination of another such hybrid, S. arranensis by the rowan s. aucuparia. It makes a nice small tree and should be more widely planted! [Information board at the Arboretum].

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Sorbus pseudohupehensis

Hupeh rowan

A.k.a. Chinese mountain ash. A medium sized deciduous tree forming a compact crown, with blue-green, pinnate leaves turning vivid red and orange autumn colours. White berries start out pink before turning white, and are produced in large clusters. Discovered by Ernest Wilson in 1910.

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Sorbus sambucifolia

Siberian mountain ash

A short-lived, deciduous shrub up to 3 m in height. The twigs are prominently covered with lenticels. The flowers are white to pinkish, in an inflorescence of up to 10 flowers that tend to hang. The 1cm wide fruits are oval and red or orange.

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Sorbus subfusca

Brown rowan?

I can find very little about this species of sorbus, other than it is a native of NE Turkey, and the white flowers will turn to red berries, and subfusca is Latin for dark brown.

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Sorbus torminalis

Wild service tree

Although rare, the service is often found in old oak and ash woods - it's an ancient woodland indicator. It is native to the UK and parts of Europe, Africa and Asia. The flowers are hermaphrodite containing both male and female floral organs: pistils and stamens , and develop into brown-green berries (chequers) which are said to taste like dates. They are used for flavouring drinks.

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Sorbus wilsonii

Chinese rowan

A native of China, a small shrub or tree, growing up to 10m. It has become widely available in cultivation since 1985. It has large pinnate leaevs with 7 pairs of leathery leaflets, and large creamy-white inflorescences, followed by equally large clusters of berries.

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Syringa sp.

Hybrid lilac

A hybrid lilac shrub growing in the dogs-run-free area of the arboretum, pointed out by director John Grimshaw on a "Meet the trees walk". Not sure of the cultivar. The common species, s. vulgaris, is a native of the Balkans; it has been widely cultivated (in Britain since 1596), and has naturalized across most of Britain.

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Tetracentron sinense

Tetracentron

A medium-sized deciduous tree (10m in cultivation, 30m in the wild) native to E. Asia central to southwestern China, N Vietnam, N Myanmar, E Nepal, Bhutan and NE India , with a broad-rounded crown that features gracefully arching branches clad with alternate, acuminate tapering to a point (leaves) , heart-shaped leaves with rugose crinkled, corrugated surfaces and serrated margins. Small stalkless, yellowish green, wind pollinated flowers in slender pendulous catkins 10 to 15cm long bloom in early summer. Flowers have no petals, with four sepals, four stamens and four carpels. Fruits are brown 4-celled, deeply lobed, dehiscent follicles mature fruits split open on impact with the ground . The tree is similar in appearance to Cercidiphylum (katsura tree) but it has alternate leaves. Now rare in its native habitat, currently listed on CITES Appendix III(Convention of International Trade of Endangered Species) [Missouri Botanical Garden].

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Tilia americana

American linden

Native to E North America, also known as basswood - a name often used for the timber from the tree. It grows quickly, and can reach 40m, living for up to 200 years. It is a good source of pollen from its small, fragrant, yellowish-white clusters of flowers. Whitish-green bracts are attached to the flowers.