Plant 102

Decaisnea insignis (Griff.) Hook.f. & Thomson (Lardizabalaceae)


Deadman's fingers

In the small family Lardizabalaceae, the genus Decaisnea is unusual; it is a thick-branched, deciduous shrub rather than a woody climber. Lardizabalaceae is related to plants such as berberis, buttercups and poppies, and has a disjunct distribution between Chile and south east Asia (where the majority of species diversity occurs).

The generic name Decaisnea commemorates the nineteenth-century Belgian botanist Joseph Decaisne, who undertook pioneering investigations of the Lardizabalaceae. The common name is a reference to the cylindrical, rather rubbery, necrotic-purple-black fruits of Decaisnea fargesii which resemble in appearance and texture a dead hand, or according to one author 'blue caterpillars'. Despite appearances, the fruits are edible. The white, gelatinous pulp surrounding the black seeds has a rather sweetish, aromatic flavour. Mature fruits are locally important in the diet of the Lepcha people of the Himalayas.

Decaisnea has long, pinnate leaves, towards the end of stout branches, and long strings of greenish-yellow flowers. Individual plants are monoecious (separate male and female flowers on the same plant), with each flower lacking petals. The natural distribution of Decaisnea extends through eastern, central and western China to the Himalayas and Myanmar.

Despite the breadth of its distribution, only one or two species have been recognized: Decaisnea insignis and Decaisnea fargesii. Decaisnea insignis occurs in cloud and montane forests of northern India, Myanmar and Bhutan at elevation between 2000 m and 3000 m; it has leaves up to 2 m long with more than 15 leaflets and warty, yellow fruits. In contrast, Decaisnea fargesii is found in Chinese and Nepalese woodlands and scrub between 500 m and 2500 m elevation; it has leaves up to 1 m long with fewer than 15 leaflets and pimply, blue-purple fruits. Some researchers choose to regard Decaisnea as a single very variable species that is polymorphic for fruit colour. In which case, the scientific name is Decaisnea insignis.

Decaisnea fargesii is widely grown in the UK and will survive temperatures below freezing. It was first collected in western China by the French missionary and prolific collector of Chinese horticultural plants Paul Guillaume Farges in 1895. Seeds were sent to the horticultural company Messrs. Vilmorin of Paris who gave seed to the Royal Botanic Garden Kew in 1897; the plants flowered in 1901. Decaisnea insignis, discovered by the British physician William Griffith in northern India 1838, is a rather more tender plant and is unlikely to flourish outside in Britain.

Further reading

Christenhusz MJM 2012. An overview of Lardizabalaceae. Curtis's Botanical Magazine 29: 235-276.

Stephen Harris