49i 



The Lautana mixta, formerly very abundant in Singapore as well 

 as elsewhere in the Peninsula, was considered a pestilential weed, 

 being of rapid growth and forming dense thickets difficult to 

 eradicate, but now seems to have disappeared to a very large 

 extent, and is hardly worth considering as a pest. The sensitive 

 plant, Mimosa pudica, has quite disappeared in many spots where 

 it was formerly abundant. 



Syncdrella nodiflora, a common South American weed, is 

 abundant in Singapore, but does not rank as a particularly noxious 

 plant. Its fruit, adhesive to cloth, etc., by its sharp spines, got 

 conveyed somehow to Christmas Island, where it throve round 

 the settlements so that it forms great patches of weed, which 

 drying up in the dry season are annoying from their inflam- 

 mable nature. There, however, weeds are comparatively scanty 

 as yet, so that it can hold its own. Doubtless in time it will 

 become less agressive as other weeds get introduced and compete 

 with it. The nut grass Cypcrus rotundus, one of the sedges, was 

 formerly a very troublesome weed in the Gardens at Singapore. 

 It is a common plant all over w arm countries, and is particularly 

 troublesome on account of its underground tubers, which are 

 produced on long creeping stems, so that when the plant 

 is dug out of the ground it is impossible to avoid leaving 

 some tubers in the ground which quickly spring up again. The 

 plant almost disappeared from the Gardens at one time, though 

 annoyingly abundant previously, but of late years reappeared in 

 some quantity and again required extirpation. Very few of these 

 weeds hold their own and become very abundant pests for any 

 great length of time in one spot, but there are some which 

 undoubtedly do so, and the best known of these is the Lalang 

 grass, which has occupied the same ground in some places for 

 a very great number of years so far as is known, but even that in 

 time gets driven out frequently by other plants. The cause of any 

 given plant becoming an excessively abundant pest and then dying 

 out is not at all clear. In some cases it will be found that it 

 only becomes a pest when it practically has the monopoly of the 

 ground, but gradually other weeds get in and eventually the 

 monopolist is killed by competition. Lalang chiefly holds the 

 ground by virtue of its having its persistent rhizomes at a con- 

 siderable depth below the surface of the soil. The leaves and 

 flower stalks are very inflammable when dry, and in many 

 places being often fired any other competitive weeds growing 

 through it, together with their seeds lying on the surface of the 

 ground, are destroyed, while the lalang itself is unhurt, and 

 immediately shoots up again. Where the lalang is prevented from 

 being burnt the creeping grasses may get in and drive the lalang 

 out by covering the ground with a mat of creeping stems. 



The Purslane, Portulaca ubracea, a weed probably of seashore 

 origin whose native home is not known, is much disliked by 

 planters, though really much less harmless than most weeds. 

 It can only grow on almost or quite bare ground, so that it is 



