DISPERSAL OF SEEDS. 154 
the seeds at liberty within the capsule. They are then easily shaken 
out. ‘The seeds have a membraneous wing all round them which 
also helps their distribution, 
Another instance of a capsule opening by pores is the common 
Snapdragon (ANTIRRHINUM MAJUs). There are three large pores, the 
openings of which are protected from the wet by their torn edges 
turned outwards. The capsule is divided into two chambers, the 
two front pores discharge the seeds from the front chamber, and the 
top pore from the back chamber. The seeds are very small and 
irregular in form, well adapted to be dispersed by the wind. 
Linarta vuncaris (Yellow Toad Flax) has an erect capsule 
splitting into several valves and setting free a large number of 
small winged seeds. It grows to a foot or more in height. 
Linarta CymBarariA (Ivy-leaved Toad Flax) is just the reverse 
of the last, as soon as the flower is fertilised, it turns round and hides 
the capsule in any dark hole or cranny; as its usual habitat is an old 
wall, there are plenty of these to be found. The stems are long and 
trailing so that it finds fresh ground each season, even after thrust- 
ing its seeds into dark corners. These two plants are a good example 
of different methods of seed dispersal by two closely allied species, 
but of quite different habitat. 
We now come to our third Section—Seeds carried by Animals 
and Birds. 
A great number of plants have a hook or hooks on some part of 
the seed, or on that portion of the plant containing the seeds. 
In the case of the Burdock the whole flower head is covered 
with hooks ; in fact, all the involucre bracts terminate in a sharp 
hook, so that anything rubbing against the plant when the seeds are 
ripe takes off a parcel of seeds with it. The seeds are also provided 
with a pappus. 
