NOTES ON THE FAUNA AND FLORA OF SARAWAK. 205 



of the Dipterocarp, Shorea ghyshertiana, which is exported to 

 England for the benefit of the soapmakers, always appears on the 

 market in the early months of the year. 



A phenomenon familiar to all who have lived in the Malayan 

 region is the curious periodicity of flowering of certain orchids. 

 The best known example is that of the pigeon orchid Dendrohwm 

 crumenatum, an epiphyte growing abundantly in Sarawak. On a 

 certain day all the pigeon orchids of the town come into flower : 

 the next day the flowers are closed. About fifty days after they 

 all flower again, and in another period of perhaps thirty or forty 

 or more days another general flowering occurs ; the remarkable 

 fact is a simultaneous flowering of all the pigeon orchids in the 

 town on certain days, the intervening periods of rest being very 

 variable. In this species of orchid I found that fertilisation always 

 took place by means of bees {Apis dorsata), which visit the in- 

 florescences in swarms at about 7 a.m. I have paid much attention 

 to the practical study of the fertilisation of orchids by means of 

 insects, and have come to the conclusion that in Sarawak many 

 orchids of fine and conspicuous flowers {e.g., the magnificent 

 Phalcenopsis grandiflora) are rarely or never visited by insects 

 and seed pods are not formed ; on the other hand, small-flowered 

 orchids nearly always set many pods ; due, I believe, to the fact 

 that they are visited by ants which are able to remove the tiny 

 pollinia and to effect fertilisation. It appears that bees are par- 

 ticularly fond of blue* flowers or scented flowers, and as orchids 

 do not have blue flowers and are only rarely scented, the bees find 

 no attraction in the flowers of orchids. I have often watched 

 carpenter bees present in swarms on the blue flowers of a Vitex 

 v/hilst close by was a huge clump of Aritndina speciosa with numer- 

 ous, showy and beautiful flowers which were quite ignored by the 

 bees. Large skipper butterflies {Erionota thrax) are responsible 

 for the occasional fertilisation of Ariindina speciosa. 



In Java this species is self -fertilised and always produces a full 

 complement of seed pods ; in Sarawak this is never the case with 

 Arundina speciosa, but it does occur in several other orchids. 



The point I wish to emphasise is that whilst orchid flowers are 

 so specially constructed in reference to cross fertilisation by means 

 of insects, a majority of the larger flowered orchids are never 

 visited by insects. 



A group of plants which attains to a specially rich development 

 in Sarawak is the Ferns. Not only are they very numerous in 

 species, but also the ferns of Sarawak are much bigger, speaking 

 generally, than those of South Africa. The tree ferns {Alsophila 

 spp.) often reach a height of over 30 feet, and even in the Hymeno- 

 phyllacese, a family of ferns which are usually small or minute, 

 Sarawak has a number of species which are comparatively large 

 {Trichomanes maximum, rigidum and foeniculaceum). The total 

 number of species known from Sarawak must be at least 400, f 



* Probably because of the nectar contained in such flowers and not on 

 account of the colour itself, though this would act as a guide to the food 

 within. 



t In T. R. Sim's Book the number of known ferns in South Africa is 

 given as 157. * 



