On the Dispersal of Seeds by Wind. 
BY 
HENRY N. RIDLEY, F.L.S., 
Director of the Botanic Gardens , Singapore. 
HE work of the wind as a means of seed-dispersal and of spore-dispersal 
-L is one of the most important subjects in Geographical Botany. We 
cannot say that a conclusive opinion has yet been arrived at regarding it.’ 
Thus writes Schimper in ‘Plant Geography ’(English Edition). ‘ A, de Candolle 
and Kerner estimate the efficiency at a very low figure in the case of seed 
plants.’ This important subject having been always of some interest to 
me, I would make some suggestions and record some observations I have 
had opportunities of making from time to time in the tropics, as a contribu- 
tion to the study of the question ; and this the more readily as I have 
observed that most of the observations on the subject recorded have been 
made in cold climates, where the country is more open and less afforested 
than it is on the equator. 
Seeds or fruits adopted for dispersal by wind may be put into three 
groups: (i) Winged fruits or seeds, such as those of most of the Diptero- 
carpeae and Bignoniaceae ; (2) Plumed fruits or seed, e. g. Compositae and 
Apocynaceae ; (3) Powder-seed, fine and dustlike, as in Orchideae or Fern 
spores. 
Wing-seed. 
In the Malay Peninsula we have a considerable number of trees of 
great size and also of lofty climbers which have winged seeds or fruit, and 
which are disseminated from the parent tree by the aid of these wings. 
To what distance do these seeds or fruits travel, and what is the rate of 
progress in this way of the species over a given area ? 
I will first deal with the wing-fruited Dipterocarpeae, of which a number 
of species occur in the jungle in the Singapore Botanic Gardens and are 
fruiting at the present time (September). The weather is squally, with 
often violent storms of wind and rain of short duration. Prolonged violent 
wind is very rare in this country, but small cyclonic storms occasionally 
occur. Typhoons such as are characteristic of the Chinese sea are quite 
[Annals of Botany, Vol. XIX. No. LXXV. July, 1905.] 
