IN my recent reread of a first edition (1930) of Dr Eric Georg Mjoberg’s ‘Forest Life and Adventures in the Malay Archipelago’, it was his chapter on ‘The General Character of Borneo’s Primeval Forests’ that caught my attention and especially his mention of tree orchids: “Amid the modest monotony of the green leaves, the most splendid blossoms appear, from the oddest single flowers to giant clusters of most charming orchids which develop in comparable form and colour.”
Never once does he refer to these tree orchids as epiphytes. This Swedish zoologist and ethnologist (1882 to 1938) was a former curator of the Sarawak Museum from 1922 to 1924, who eventually left Kuching in 1926.
The word epiphyte is derived from the Greek ‘epi’ meaning upon and ‘phyton’ meaning plant. Actually such plants spend their lives upon the aerial structures of other plants without abstracting any water or nutrients from their hosts. Simply, it is not a parasitic form of vegetation.
Epiphytes must not be confused with saprophytes, for the latter are organisms that act as rainforest decomposers and are often seen in fungi form on fallen dead trees or amongst the leaf litter of the forest floor. A saprophyte recycles nutrients from dead organic matter, whether vegetable or animal, returning vital elements to the soil for other plants to reabsorb.
During the years I spent teaching in Kuching and in frequent visits subsequently, I have followed, with great envy, the plethora and development of tree orchids in friends’ gardens as well as the growth of epiphytic ferns along the tree-lined avenues of the city and beyond.
In the United Kingdom, I have my own collection of indoor varieties of tree orchid, which I can admire in summertime and hothouse conditions during the winter months. There are over 18,000 species of orchid in the world with another 10,000 to 12,000 species yet to be described.
Of the known orchid population, 70 per cent of varieties are epiphytes. Many terrestrial and non-epiphytic species of orchid are found on lowland sites threatened by development of many kinds, such as road construction, swamp drainage and building construction sites on former river floodplains. This is a universal problem.
One such species I noticed during a walk to a kampung area shortly before it was to become a massive housing development. I reclaimed clumps of this orchid together with the soil in which it grew just as the bulldozers arrived to clear the area.
Now in two clumps in large pots in the porch of a friend’s house, the orchid Arundina graminifolia on its cane-like stalks is a sight to behold. It is a species that enjoys a sunny aspect.
Epiphytes belong to 83 species of plants that we recognise as orchids, ferns, lichens, mosses, bromeliads and even cacti. Cacti we normally associate with arid, desert environments, but the rainforest cacti, instead of spikes and thorns, possess elongated leaves for sunlight absorption.
I have always had an interest in epiphytes in the temperate climes of Europe but even more so those in Borneo, where, in two treks into the Danum Valley and one climb to the summit of Mount Kinabalu, the very range of epiphytic species deepened my fascination.
This fascination is rooted in the ability of these plants to anchor themselves on decomposing leaves trapped in the crotches of tree branches high aloft. They are truly air plants deriving nutrients from the air, rain and compost, assisted by the abundant heat and moisture of the rainforest.
Whilst the canopy of the rainforest displays the beauty of the dominant tree species, forever growing upwards to gain maximum sunlight, it is in the next layer of trees below, sometimes referred to as the mid-canopy, that epiphytes are most abundant. There, epiphytes receiving medium exposure to sunlight, and particularly tree orchids, are happily ensconced.
Epiphytes grow in niches in the rainforest where particular microclimates suitable for their emergence occur. A tree orchid produces hundreds of thousands of minute seeds, with each seed coated in a balloon-like substance thus allowing the seeds to be easily dispersed by the wind.
Insects also spread this epiphyte’s pollen, as do passing animals and birds. There is a symbiotic relationship between an epiphyte and visiting animals, birds and insects, for the excreta emitted by these creatures is absorbed by the plant as a form of soil fertiliser.
There are some tree species that reject epiphytes, because of their peeling barks, thus preventing the accumulation of dead litter from their canopies. Yet other trees emit toxins in their barks to discourage epiphytic development.
The most eerie forms of epiphytes exist in the cloud or moss forests of Mount Kinabalu. There the lichens and mosses bedeck the wind-blasted gnarled trees with their dangling appendages in will-o’-the-wisp-like forms. Those epiphytes are not dissimilar to those I have seen growing on ancient oak trees at Wistman’s Wood in a wind-exposed part of Dartmoor National Park in the UK.
Even in the backwoods of Somerset, UK, in midwinter when there no leaves at all on the deciduous trees, I marvel at the variety of epiphytic ferns, mosses and lichens that survive in their own microclimates on the branches of trees in my garden and beyond in the trees aligning the river banks in a nearby sheltered valley.
They provide a glimmer of hope of life beyond the death of the canopy leaves and suggest that, with springtime around the corner, more sunshine and rain will see bigger versions of these epiphytes next year.
Epiphytes, worldwide, are some of the most sensitive of plant species, which have already indicated that climatic change is in progress by altering their altitudinal and spatial habitats.
To learn more read: ‘The Orchids’ by A Lamb and CL Chan (Sabah Society Monograph, The Sabah Society 1978) particularly Chapter 8 — ‘Kinabalu – Summit of Borneo’ and Chapter 9 — ‘The Ferns’ by R E Holttum; ‘Mount Kinabalu – Borneo’s Magic Mountain’ by KM Wong and CL Chan (Natural History Publications, Borneo, Kota Kinabalu 1997); and ‘Forest Life and Adventures in the Malay Archipelago’ by Dr Eric Mjoberg (Allen and Unwin, London 1930).