OF THE MALDIVE ISLANDS. 
145 
Asclepiads, Tylophora asthmatica and Leptadenia reticulata, 
found in the Laccadives, and a third, Asclepias curassavica, 
in Diego Garcia. The presence of the first, which is widely 
spread in the islands, may be due to intentional introduction, 
as its root is a valued medicine, used as ipecacuanha, but 
there is a chance that the second may have been introduced 
by wind, and thus have been carried about 150 miles. Ascle- 
pias curassavica may have been carried to Diego Garcia by 
wind, but is a cosmopolitan tropical weed wherever cultiva- 
tion occurs. 
Lastly, there are the pappose Compositæ, but with regard 
to all these, which, as a glance at the list will show, are the 
commonest of Indian weeds, there is at least as much like- 
lihood of accidental introduction through the agency of man, 
and no deductions as to wind transport can be based on their 
presence, though their commonness in the islands is no 
doubt partly due to their easy local transport by wind. 
Another argument against any great transport by wind is 
the poverty of the insect fauna of the islands. The north- 
east monsoon brings a few butterflies and other insects from 
India, so that it is possible that some of the parachute seeds 
or fruits, e.g., those of Asclepiads or Compositæ, may be 
carried over also. 
Introduction of Plants by Ocean Currents. 
Of all the agencies in the stocking of oceanic islands, this 
is the most important, and it has been fully described by 
Schimper,* Hemsley,! and others. Many, especially the 
most widely distributed, of the littoral plants of the tropics 
are provided with admirable adaptations for the floating of 
their seeds or fruits over long fstretches of sea. There is no 
need to go into details here with regard to these mechanisms. 
We shall merely extract from the lists of plants of the 
Laccadives, Minikoi, Maldives, and Chagos the species about 
* Die Indomalayische Strandflora. Jena, 1891. 
f Botany of the Challenger Expedition, Vol. I., 1885. 
