APPENDIX 



tropics. Some are hygrometric or hygroscopic, able to resist drought 

 for a long period, and to profit by ever so slight an amount of rain or 

 aqueous vapour suspended in the surrounding air. To this category 

 belong several ferns (Hymenophyllacece mostly) and various other vascular 

 and cellular Cryptogams. Many epiphytes have thick and rather 

 fleshy leaves, others have stems or roots with tuberous, bulbiform, or 

 otherwise thickened enlargements. In some the vegetative organs are 

 clothed with a waxy or varnishy layer, more rarely with hairs {Eria 

 amongst the orchids). All these modifications are simply means for 

 diminishing evaporation and maintaining the vitality of the protoplasm 

 of their tissues. A great many epiphytes have the property of con- 

 densing atmospheric aqueous vapour, especially on their roots. It is 

 thus that many orchids manage to grow, having most of their roots sus- 

 pended in the air. 



The condensation of aqueous vapour is one of the most important 

 conditions for the existence of epiphytal plants, and it is perhaps for 

 this reason that many, for instance a large number of orchids, prefer 

 smooth barks in trees, which being inferior heat-conductors to cork-like 

 barks, condense more readily the aqueous vapour with which the air 

 is laden. 



One might well describe the epiphytes as the misers of the vegetable 

 kingdom, for they economise every thing, seeking to spend as little' as 

 possible, and utilising even the smallest resources in the way of food 

 and drink. 



The epiphytes of Borneo belong to the following families : — Orchidece, 

 Asclepiadece (Hoy a and Dischidia), M elastomacece (Medinilla and Pachy- 

 centria), Rubiacece (Myrmecodia, Hydnophytum), Araliacece (Hepta- 

 pleurwn), Loganiacece (Fagrcea), Urticacece (Conocephalns). Some plants 

 of the genera V actinium, Diplicosia, Rhododendron, Nepenthes, Pandanus, 

 and Freycinetia are also epiphytes, besides several Zingiberacece, many 

 Aracece, ferns and others. 



From a certain point of view it seems to me that there is a kind of 

 analogy between epiphytes and alpine plants, to which perhaps certain 

 conditions of temperature are not as essential as a given amount of 

 humidity, abundant light, and most probably the necessity of avoiding 

 the neighbourhood of a number of other plants, with whom they could 

 not struggle advantageously on the ground. In many of the Bornean 

 epiphytes this resemblance is great. It is sufficient to mention the rho- 

 dendrons, amongst which R. Brookeanum flourishes at sea-level on 

 mangroves on the equator ; whilst in the arctic regions R. Lapponicum 

 resists any amount of cold. 



Orchids.- — Amongst the epiphytes of Borneo the Orchidece hold the 

 first rank, both for the number of species and for the beauty of their 

 flowers. Some of the most splendid orchids known are natives of Borneo. 

 It is, however, a mistake to suppose, as many do, that beautiful flowers, 

 and especially those of orchids, are common in equatorial forests forming 

 conspicuous masses of bright colour. One may wander for days in a 

 Bornean forest without seeing a single brilliant flower. If all the Bornean 

 plants bearing brightly-coloured flowers could be collected in a hothouse, 

 and if they could be had in blossom at the same time, the sight would 



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