Plant of the Month: May

Davidia involucrata var. vilmoriniana Common name: handkerchief tree, dove tree, ghost tree Family: Davidiaceae Vital statistics Height and spread: 15m (50ft) high and 10m (33ft) wide Form: Deciduous tree Soil: Moist, well-drained soil Aspect: Sun or partial shade, protected from strong winds Hardiness: Hardy throughout the British Isles

Nestling in the back of the Winter Garden border, set between a large specimen of Prunus lusitanica and a even larger specimen of Taxus baccata, there is a fine specimen of Davidia.

This specimen is approximately 25 years old and started to flower 10 years ago, it now produces a magnificent display each spring when it is completely covered with showy white bracts which turn green as they age.

Davidia

Davidia is a monotypic genus (which means it contains just one species) and is native to deciduous woodland in western Sichuan and Hubei provinces in China. It is best known for its striking large, white bracts which are borne in spring.

Davidia was first discovered near Mupin in 1869 by Abbé Armand David and subsequently named in honour of him. David (1826-1900) was a French missionary in China between 1862 and 1873 who collected many plants and animals.

The first introduction of Davidia was in 1897 when 37 seeds of D. involucrata var. vilmoriniana were sent to Maurice de Vilmorin by the French missionary Père Farges. Unfortunately only one seed germinated, and that was not until June 1899. It grew and flourished, flowering for the first time in May 1906 at Les Barres.

Further introductions were made, in particular, by Ernest Wilson who sent back some 13,000 seeds of D. involucrata var. vilmoriniana during his first expedition to China in 1899-1901. During his next expedition to China he also sent back seed of the original D. involucrata.

Davidia involucrata var. vilmoriniana

A conical tree with broadly ovate, sharp-pointed, toothed red-stalked leaves which are scented when young. Unlike the leaves of Davidia involucrata - which have hairy undersides - D. involucrata var. vilmoriniana has leaves that are almost hairless and dark green beneath. Flowering in late spring it produces small flower heads surrounded by two, unequal, showy white bracts up to 30cm (12in) long, which give rise to the common names.

The flowers are made up of dense, pendent heads up to 2cm (3/4in) across, of small male flowers each with showy red-purple anthers and a single ovary. Each flower is surrounded by a pair of leafy, white bracts of unequal size.

Pendent, ridged fruit, borne in autumn are greenish brown and up to 4cm (11/2in) across.

Davidia involucrata var. vilmoriniana is named in honour of the firm Vilmorin-Audrieux of Paris, notably Maurice de Vilmorin the celebrated French nurseryman and seedsman who grew the first plant.

Both davidias are best grown as a specimen tree so the beauty of the spring flowers can be enjoyed and the attractive, smooth but flaking, mid-grey bark can be seen.

AGM

The RHS Floral Committee B awarded Davidia involucrata var. vilmoriniana an Award of Garden Merit and described it as: 'Medium-sized deciduous tree with broad ovate, hairless leaves to 15cm long. Small globose heads of tiny green flowers within a pair of conspicuous ovate white bracts to 20cm long.'

Cultivation

Grow as a specimen in fertile, moist but well-drained soil in sun or partial shade. Best grown in a sheltered location from strong winds which could otherwise damage the tree.

Formative pruning is essential in the first five years as Davidia is best grown as a central-leader standard with a clear trunk tall enough to allow access below to view the bracts from beneath. The tree naturally forms a strong central leader surrounded by strongly upright laterals. These can usually be allowed to grow unless they overtake the leader, in which case they should be removed.

Established trees need no special attention and do not respond well to hard pruning.

Davidias are pest and disease free.

Propagation

Propagated readily from seed after an extended period of dormancy but will not flower for up to 10 years from germination. Sow the whole fruit, as soon as it is ripe, in a seedbed or containers in an open frame. Germination normally occurs in spring after two winters. In the wild it has been noticed that all the seeds germinate at once with one eventually crowding out the others.

Cuttings can also be taken, either in early autumn as leaf-bud cuttings or in winter as traditional hardwood cuttings.