Ridley .— The Distribution of Plants . 9 
to form herbaria, they gave no information as to whether the specimens were 
obtained in altered or cultivated ground or not. 
Weeds commonly follow the tracks of the largest migrations of man. 
The greater number of weeds in the Malay Peninsula are South American 
or more probably West Indian in origin. 
In the sixteenth century the Jesuits brought useful plants from South 
America to Manila, their most important station in the East Indies. They 
brought the pineapple, Capsicums, Papaya, Achras sapota, Cashew-nut, and, 
apparently as a curiosity, the Sensitive plant. Most of these plants, the 
useful ones at least, were conveyed to Goa, and thence to Malacca, where 
Linschoten records them in 1583. It must have been in those days that 
most of our Malayan weeds came to Asia, but they appear to have come 
mainly to the Malay Peninsula through Java from the Philippines at a later 
date, for nearly all are abundant in Java and there are still a number of common 
weeds there which have not yet reached the Malay Peninsula, the stream of 
human migration to which has been strongest from Java. 
We possess fewer weeds from India because, until the extensive intro¬ 
duction of Tamil labour, there was but slight migration from India. A few, 
chiefly medicinal plants, Eryngium foetidum , Linn., and Leonurus sibiricus , 
Linn., have been brought by the Chinese. Once in the country the area 
which one of these plants occupies depends on its adaptability to various 
classes of position and soil, or perhaps, more strictly speaking, to the extent 
of the area with suitable soils and conditions, and secondly to its means of 
dispersal. 
Plants which thrive in made soil, or cultivated ground, will spread as 
far as there is any such ground ; those to which the sandy and gravelly 
drier roadsides are suitable will spread as far as such roads go. 
Plants with adhesive fruits or seeds seem to travel fastest and farthest; 
such plants are Paspalum conjugation , Berg., Ageratum conyzoides , Linn., 
and Bidens , and it is interesting to note that most of the tropical weed 
Compositae, and the most abundant, are those with adhesive fruits, not those 
with plumed achenes. 
Weeds with berries, bird-dispersed, such as Solanum oleraceum and 
Pcissijlora foetid a,'Linn., also travel fast, and many small herbs with minute 
seeds, such as the herbaceous Rubiaceae, Oldenlandia and Borreria , the 
small Euphorbias like E. thymifolia , Linn., and very many Grasses ; mostly 
roadside weeds are quickly distributed by rainfall. 
Some of these plants are now among the most widely distributed 
species in the world, and it can be readily shown that the duration of time 
in which the plant has been in its extended area plays practically no part in 
the wddeness of its distribution. In other words, age has little or nothing to 
do with area. 
It is unnecessary here to give a list of the weeds introduced into the 
