Dove-tree

The saluting tree

In May the handkerchief (or dove) tree waves at us with its distinctive inflorescence. The conspicuous 15 cm long, pendulous bracts (the handkerchiefs) protect the actual flower. The meaning of its species name, involucrata, refers to these obvious involucres.

A French priest, Father David, discovered the tree in China in 1869 and later the tree was named after him. The first seeds were germinated in Paris in the early 20th century and the first ‘handkerchiefs’ appeared in 1906.

Davidia produces nut-shaped fruits, with up to three seeds per fruit, and can grow up to 10 m. After the ‘handkerchiefs’ have dropped, the beautiful purple coloured nut-like fruits dangle on long stems. In the wild this is an endangered species.

The variety vilmoriniana differs in its degree of hairiness.

The function of the large white bracts, the handkerchiefs, is two fold: they both protect the pollen from rain, and attract – through a process involving ultraviolet absorption – pollinating bees and (to a lesser extent) pollinating beetles. Predominantly bees effectively pollinate the flowers because they visit a different flower every 4 to 5 seconds whilst beetles can sit for 1 to 2 hours on a single flower.

Standard bearer of a partially defeated army

The Dutch vernacular name ‘vane tree’, and the common English name ‘pocket handkerchief tree’, are both derived from the white bracts, up to 15 cm long, that surround the inflorescence. The flowers themselves are small and discrete. When Davidia flowers in May the tree appears to be full of little white flags or handkerchiefs. When the breeze blows, the white flags flutter like doves’ wings, hence the alternative common English name, ‘dove tree’. The pocket-handkerchief tree is the only species in the genus Davidia is named after the Frenchman Father Armand David (1826-1900), missionary and naturalist.

Ecology and habit

China is a refuge for many primitive flowering plants from the Tertiary. As with Madeira for example, Central China harbours many endemic species that were more abundant and widespread before the last Ice Age. The pocket-handkerchief tree is the standard-bearer of this partly defeated army. In the wild it can be found growing mainly on mountainsides between 1000 and 1500 m in the transition zone between the evergreen and broad-leaved forests. The pocket-handkerchief tree is distributed across much of Central China but is nonetheless rare.

Threat

Davidia is a textbook example of a species, which despite a relatively large distribution is succumbing to an ever-expanding population. Increased felling and agriculture in China during the last century has led to a loss of much of the natural landscape and associated endemic species. This demand for land has not yet peaked with projects still underway such as the construction of the Three Gorges Dam that will render much agricultural land useless. The dam will raise the level of the Blue River to 300 m above sea level – not high enough to drown the pocket-handkerchief trees but who is preventing the displaced farmers from looking for new land higher in the mountains?