49 1 
The I.autana mixta, formerly very abundant in Singapore , as weU 
elsewhere in the Peninsula, was considered a pestilential weed 
beine of rapid growth and forming dense thickets difficult to 
eradicate but now seems to have disappeared to a very large 
extent^ and is hardlv worth considering as a pest. The sensitive 
plant " V imusa pudica, has quite disappeared in many spots where 
common South American weed,, is 
abundant in Singapore, but does not rank as 
n i,nt Its fruit, adhesive to cloth, etc., by its sharp spines, b oi 
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 
""yet o that it can- hold its own. Doubtless in time it will 
become less agressive as other weeds get introduced and compete 
S it. Tlmnut grass Cypcrus rotundus, one of die sedges, was 
formerlv a verv troublesome weed in the Gardens at . lngapore. 
It is a common plant all over warm countries, and is particulaily 
troublesome on ‘account of its underground tubers w cl, are 
produced on long creeping stems, so that when P 
s dim- 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. \ err few ot these 
weeds hold their own and become very abundant pests for an) 
"real length of time in one spot, but there are Some which 
undoubtedly do so. and the best known of these is the Lalang 
"which has occupied the same ground in some places for 
a verv meat number of years so far as is known, but even that in 
time °ets driven , mt frequently by other plants. The cause of any 
iven plant becoming an excessively abundant pest and then dying 
o t ,s not at all clear. In some cases it will be found that it 
only becomes a pest when it practically has the monopoly of he 
ground, but gradually other weeds get in and eventually the 
monopolist is killed by competition. Lalang chiefly ds the 
..round bv 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 g-0\ g 
through it, together with their seeds lying on the surface of the 
mound, are destroyed, while the lalang itself is unhurt, and 
immediately shoots up again. Where the lalang ^prevented from 
being burnt the creeping grasses may get m and drive the a g 
out by covering the ground with a mat of creeping s ems. 
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. 
