68 PLANT MIGRATION 
when the fruit is young or during damp weather, but 
on a dry day when it is ripe they spread out, and the 
seed, breaking away from its attachment, is floated 
off by the wind. In many species the plume or 
pappus is only lightly attached to the seed, so that if 
FIG. 13.—WING-SEEDS AND PLUME-SEEDS. 
a, Mountain Willowherb (Epfilobium montanum), 7; 6, Dandelion 
(Taraxacum officinale), 2 ; c, Mountain Avens (Dryas octopetala), } ; 
d, Scotch Fir (Pinus sylvestris), 2; e, Reed-mace (Typha lati- 
folia), 2. 
on a voyage an obstacle is encountered the seed drops 
off, while the now useless parachute drifts away. But 
though the plume seeds of the Composite are the 
largest and most beautiful among our common plants, 
they are not the most efficient for dispersal. The fluffy 
seeds of the Willowherbs (Epilobium) and of the 
Willows (Salix), for instance, fall at a slower rate than 
