APPENDIX 



The large quantity of humus accumulated in the forest predisposes, 

 even in great trees, to the development of numerous superficial roots 

 This, perhaps, is one of the reasons why the forest species can only thrive 

 in the secondary forest after many years, when a thick stratum of humus 

 has been formed. For the smaller plants of the underwood this kind 

 of soil must be an essential condition of existence, as is proved by the 

 fact that most of them cannot exist elsewhere. 



As trees in these forests find abundant nourishment in the humus, 

 it appears natural that their roots should not penetrate vertically into 

 the ground, but extend along its surface. This is, I think, the true cause 

 of the development of " banners " or laminar expansions from the base 

 of the trunk. The stability of these giant trees which, owing to the lack 

 of deeply penetrating roots, is rather deficient, is thus greatly augmented. 

 The banners have been called " laminar roots," but in reality they cannot 

 be thus described, except in some cases when they extend along the 

 ground, reaching far from their trunk. In most cases however these 

 laminar expansions grow out at a considerable height above the level 

 of the ground. One meets" with trees, especially in localities where the 

 forest is habitually flooded, whose trunks appear as if lifted above the 

 soil by their roots. The best instance of such stilt-like roots in the 

 Sarawak forests is that shown by Plojarhim pulcherrimum, Becc, 

 whose stem is provided below with laminar expansions, and raised in 

 the air by branched roots, just as if the entire plant was hoisted out of 

 the soil for six or eight feet or more. This form of roots is quite different 

 from that which may be termed " fulcral," peculiar to the screw pines 

 and some Eugeissonias, and especially to mangroves. In these plants 

 new adventitious aerial roots are constantly being produced from the 

 stem or trunk pari passu with the growth of the tree, or else secondary 

 roots grow from the older ones, and all eventually penetrate into the 

 soil. 



The abundance of creepers and rope-like palms such as Calamus 

 and allied genera are salient features of the great Bornean forest, as 

 are also the large number of epiphytes and parasitical plants on the tree- 

 trunks and branches ; the rich collection of undergrowth plants ; the 

 multitude of humicular species, of ant-harbouring plants, and of 

 urnigerous or pitcher plants (Nepenthes) ; and the existence of species 

 producing flowers and fruit on the trunk or around its base, on 

 the main branches, and even on underground growths. But all these 

 find a perfect correspondence in analogous forms to be met with in the 

 equatorial forests of the New World. 



Amongst the plants' which live under the shade of other vegetation, 

 those that have leaves with a large surface area often predominate. 

 In this category are found not only herbaceous plants, both terrestrial 

 and epiphytic, Aracece, Gesneracece, Marantacece, Zingiber acece, etc., but 

 also many shrubs peculiar to the underwood, which flower and fruit 

 protected by the larger trees, and often show large leaves. To this group 

 belong many Anunacece, Magnoliacece, Euphorbiacece, Laur acece, Myristi- 

 cacece, etc. Many of the underwood shrubs which have not large simple 

 leaves, have composite leaves, such as many Leguminosce, Meliacece, etc. 

 The majority of the giant trees have medium-sized or small leaves, 



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