114 
PLANT STUDIES 
that at least 
fourteen per 
cent, of the 
seeds of any 
country can re- 
tain their vital- 
ity in sea-water 
for twenty- 
eight days. At 
the ordinary 
rate of move- 
ment of ocean 
currents, this 
length of time 
would permit 
such seeds to 
be transported 
over a thou- 
sand miles, 
thus making 
possible a very great range in distribution. 
77. Dispersal of spores by air. This is one of the most 
common methods of transport- 
ing spores and seeds. In most 
cases spores are sufficiently 
small and light to be trans- 
ported by the gentlest move- 
ments of air. Among the 
fungi this is a very common 
method of spore dispersal (see 
Fig. 106), and it is extensively 
used in scattering the spores 
of moss-plants, fern-plants (see 
Fig. 45), and seed-plants. 
Among seed-plants this is one 
method of pollination, the 
FIG. 113. A ripe dandelion head, showing the mass of 
plumes, a few seed-like fruits with their plumes still 
attached to the receptacle, and two fallen off. After 
KEENER. 
FIG. 114. Seed-like fruits of Senecio 
with plumes for dispersal by air. 
After KEBNEK. 
