THE VIRGIN FOREST 



over the production of new leaves ; and the more enduring nature 

 of the foHage of the tropical trees is one reason why tropical plants 

 produce fewer leaves than those of the temperate zone. But there 

 is, of course, yet another reason for the solid construction of tropical 

 foliage; the leaves have to resist the tropical rains, when the water 

 comes down as though poured out of buckets. In Java it has been 

 noted that imported European plants are beaten into the ground 

 by the rain, as though by a shower of hail. 



Other trees, like the sacred Bo-tree of India, provide their leaves 

 with a sort of pointed rain-spout, so that the water runs off them ; 

 or the leaf is divided into mere pinnules, which offer no resistance 

 to the rain. The numerous family of the Leguminosae has adopted 

 this plan, but the pinnate leaf is favoured by other groups also, as, 

 for example, by the Mimosa-leaved Jacaranda. Many of these 

 leaves are of considerable size, but are none the less so finely divided 

 that they seem the work of an artist, or produce the effect of green 

 lacework. The pinnate leaves have the power of turning to adjust 

 themselves to the light ; if the rays of the sun are too powerful they 

 turn upwards; in gloomy weather, such as occurs before the rains, 

 they sink again, and when the rains begin they at once assume 

 the position in which they will offer least resistance. 



The "Sensitive Plant," or true Mimosa, has this power of move- 

 ment in unparalleled perfection. This shrub is a native of Brazil, 

 but has been introduced into all tropical countries, and is the 

 despair of all gardeners who are trying to make a good lawn. If one 

 touches one of the pinnate leaves of the Sensitive Plant, first of all 

 the pinnules fall, and then the leaf, and then suddenly the whole 

 stalk folds downwards. Even the slight tremor caused by walking 

 on the turf releases the reaction, which is propagated like a wave ; 

 the green leaves droop, and the ground looks as though covered 

 with withered weeds ; only the rosy balls of blossom and the spiky 

 stems of the plant are still erect. It is, of course, possible that 

 the plant is not merely seeking to protect itself from the rain by 

 such behaviour, but that many herbivorous animals would draw 

 back on seeing only the apparently withered foliage and the 

 menacing thorns. 



On the floor of the virgin forests of north-eastern Brazil the 

 Bauhinias predominate, plants which belong to the Leguminosae. 

 Many of these have beautiful flowers, as large as a lily, in colour a 

 fine rose-pink ; but, curiously enough, one of the five petals is quite 

 different from the rest, being flecked with a rich, deep crimson. 



P 8i 



