ENG-1975 — Page 260

NATURAL HISTORY

Flora

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For so small an area, Hong Kong has a large and diverse flora of vascular plants. It is estimated that there are about 2,500 species, native and introduced. Generally Hong Kong offers the northern limit of tropical Asia flora.

There are few tall trees, except in the fine fung shui groves around many villages in the New Territories. Before conservation, countless hillsides were left barren by centuries of cutting, burning and exposure. Now however, many hill slopes-partic- ularly those in the water catchment areas have been replanted with tree seeds or seedlings. The ravines were saved from man and fire by their rugged character and more moist winters, and they contain a dense vegetation particularly rich in low trees, flowering shrubs and ferns.

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It is to conservation of wooded areas by the Agriculture and Fisheries Department that Hong Kong owes much of its mixed woodland. In a few large ravines, particularly Tai Po Kau and Pok Fu Lam Valley, autumn and spring colours are particularly noticeable. There are several trees, shrubs and climbers whose leaves change to brilliant colours in autumn. Plants which show richest autumn colours continue their display into February, before the start of spring. Many trees, shrubs and vines help to produce this effect-Liquidambar formosana, Rhus spp, Michilus thunbergii, Raphiolepis indica, Rourea microphylla, and Vitis cantoniensis.

Many plants in Hong Kong are exceptional for the beauty or fragrance of their blossoms. The Bauhinia blakeana (Hong Kong Orchid Tree) was discovered in 1908 at Pok Fu Lam and was named after a former Governor, Sir Henry Blake. It is among the finest of the Bauhinia genus anywhere in the world and has been adopted as Hong Kong's floral emblem. It is now widely planted.

Fruit bearing plants include the common tree the Sterculia. Its remarkable starlike fruit turns crimson in late summer and splits open to disclose jet black seeds. The seeds are eaten by a number of birds including the Chinese Blue Magpie.

A great variety of wild plants have medicinal and economic values. Parts of a common tree, Schefflera octophylla, are used in herbal medicines for the preparation of 'leung cha', a drink used chiefly for relieving indigestion. Shrubs like Psychotria rubra, Ardisia crispa and Strophanthus divaricatus are considered useful for bruises and certain injuries.

Botanical explorations carried out by the Hong Kong Herbarium, the two universities, and amateur botanists have been fruitful. The Checklist of Hong Kong Plants was revised and published in early 1975. It includes 50 new additions to the Hong Kong flora since the first edition in 1966,

More than 90 species of nature orchids are recorded. Some ground orchids are beautiful and have long been cultivated in other countries. Probably the best known of the local species is the Nun Orchid, bearing flowers four inches across with white petals and a purple lip. A new species with greenish cream-white flowers was dis- covered in 1969 by Dr S. Y. Hu and was named Cymbidium maclehoseae in honour of Lady MacLehose, who is a keen naturalist. Other species include the White Susanna