360 Ridley . — On the Dispersal of Seeds by Wind. 
ground, these plants doubtless have a more rapid dispersal than the slow- 
growing wing-fruited trees. 
The most abundant Apocynaceae, however, are those with fleshy fruit, 
dispersed by birds and mammals, or the sea-borne Cerbera . 
The Asclepiadeae have all plumed seed except Sarcolobus , a tidal river 
plant, the seed of which is adapted for dissemination by water. They are 
not very abundant in the peninsula, and fall into two classes — the slender 
climbers, like Tylophora , which occur on the edges of the rivers and over 
bushes by the sea, &c., and are absent from high jungle and mountains, 
and the epiphytic species, some Hoyas and Dischidia . Some of the latter 
are almost confined to the upper branches of lofty trees ; others like D. Raf- 
flesiana generally occur in low trees about 30 feet high in the open 
country, especially near the sea, and again on mountain-tops, but not 
between. D. coccinea occurs on very lofty tree-tops in the low country, 
and on smaller trees on mountain-tops. I believe the seeds of D. Rafflesiana 
fly to a considerable distance, but it is difficult to be certain. I have seen 
young plants about 60 yards from a tree full of old plants, but I do not by 
any means think this is their limit 
The only epiphytic Gesneraceae, Aeschynanthus and Agalmyla , have 
small plumed seed. They are much more widely distributed than the 
terrestrial species, the plumeless seeds of which are distributed by rain- 
water. 
Plumed Seeds and Fruits in Insular Floras. 
These are much rarer than one would naturally expect. One could 
easily conceive of their being carried high up into the air by a gale and 
drifted away to a distant island, but as a matter of fact plants with this 
mode of dissemination form only about 1 per cent, of the vegetation. 
In Christmas Island is one Hoy a, and Blunted spectabilis ; in Fernando 
de Noronha one Gomphocarpus ; in the Admiralty Islands one Hoya . In 
Juan Fernandez, out of 118 plants there are one Bromelia and twenty 
Compositae which may bear plumed seed ; but of these fourteen are endemic 
species, of two genera, and may of course be all descendants of two species, 
very early inhabitants of the island ; but I have no works here which state 
whether these fruits are plumed or no. 
Powder-Seed. 
The very fine powder-like seed of many flowering plants and spores of 
Ferns, Lycopodiums, and the cellular Cryptogams are well adapted for 
wind-dispersal, and are often very widely disseminated. It is, however, 
impossible to follow them in their flighty so that one has to judge of the 
distance they can go by the appearance of young plants at a distance from 
