SEED-DISPERSAL BY THE PARENT 55 
rare native of England) the bulbils resemble not the 
smooth flower-stems of which they are axillary 
branches, but the curiously knobby underground 
stems from which the leaves and flowering shoots 
arise. 
Since seeds themselves possess, as already stated, no 
power of locomotion, they have to rely on external 
agents for their dispersal. These may in general be 
summed up as (1) Action of the parent plant, (2) 
water, (3) wind, (4) animals. 
1. Action of the Parent—The Ivy-leaved Toad-flax, 
or Mother-of-Thousands (Linaria Cymbalaria), is a 
pretty little plant, native in central and southern 
Europe, naturalized and common on old walls in this 
country. Its Snapdragon-shaped purple flowers are 
borne on short stalks which curve towards the light, 
placing the blossoms in a conspicuous position, where 
they may be the more readily visited by insects, and 
thus pollinated. But when flowering is over, and the 
little round fruit is ripening, the stalk twists so that 
the fruit is turned towards the wall and finally pushed 
into any convenient crevice: when the capsule opens, 
the seeds, instead of dropping to the base of the wall 
where on germination the young plants would be 
smothered among stronger growths, find themselves 
lodged in niches in which the young plants may 
develop successfully. Many water plants have flowers 
which rise into the air, following on which the flower- 
stem curves and the seed is ripened below the surface, 
free from the dangers of weather, of feeding water 
birds, and so on. 
A very common type is that in which the seed-vessel 
opens at the top when the seed is mature. Gusts of 
