Orchids of Borneo

Orchids of Borneo
The orchid family is one of the largest and most diverse groups of flowering plants in the world. Members of the family can be found throughout the world except for the driest desert and regions permanently covered with snow. Estimates of the total number of orchid species in the world vary from 17,000 to 35,000. Borneo as the third largest island in the world. It has been considered as an “island of fruits” but could equally be referred as an “island of orchids”. Lamb (1991, in Chan et al, 1994) has estimated that 2,500 – 3,000 orchid species are to be found in Borneo or 75% of the Malesian orchid flora. Of these, 30-40% are thought to be endemic to the island. Wood and Cribb (in Chan et al, 1994) have listed over 1,400 species in the island. Some localities in Borneo can be exceedingly rich. For example, Wood, Beamen and Beamen (1993, in Chan et al, 1994) have documented nearly 700 species of orchid for Mount Kinabalu. This represents nearly a fifth of all vascular plants and perhaps nearly a half of the Bornean orchids on this mountain alone. Kersik Luway, west of Kutai in East Kalimantan has been decreed by the local Government for conservation due to its large diversity of orchids found wild in the area.
The rich orchid flora in Borneo may have come about because of several factors. The Borneo flora is enriched by the intermingling of the floristic elements of Laurasia and Gondwana land masses across early dissected land bridges joining Australia and Asia. Thus the Sunda shelf species may reach as far as east as the Cape York Peninsula in Australia, whereas Papua New Guinea species may have reached Borneo (Chan et al, 1994)
PTAYI is a production forest concession in South Kalimantan. As part of effors to document the natural biodiversity of this area, SCKPFP requested the Research and Development Centre for Biology, Bogor, part of the Indonesian Institute of Science, to provide assistance in assessing the orchid flora.

1.2 Main characteristics of orchids
In spite of the immense variety on vegetative parts, the flowers of nearly all orchids are constructed in a very distinct way. A flower of any kind usually has the following parts in successive whorls: sepals (3), petal (2), a column (1) – the combined structure of stamen, style and stigma-, and a lip (1) – a modified form of a petal. In orchids, the pollen is not powdery as in most flowers but is united into small masses called pollinia. Each pollinia contains thousands of pollen grains. A single anther contains 2, 4, 6 or 8 such masses. The orchid is not a parasite; it does not absorb food from the living parts of trees. Some orchids use a tree as a perch on which to establish themselves. These are called epiphytes which make use of decaying bark, dead leaves and other debris from which to extract nourishment, with the help of fungus. Beside the epiphytic orchids, there are also terrestrial orchids (and even aquatic ones) which grow on the ground. Some terrestrial orchids have no green leaves and are called saprophytic orchids. The whole food supply for growth is provided by a fungus which exists partly in the surrounding soil and partly in the roots of the orchids. The fungus breaks down the humus of the soil into a form which the orchids can absorb.