Fruits and Seeds. 175 



mon European species has rapidly spread over the 

 whole of South Africa, the seeds, which are covered 

 with hooked spines, being carried in the wool of 

 sheep. 



2. There are a great many cases in which plants 

 possess powers of movement directed to the dis- 

 semination of the seed. Thus, there are some 

 funguses which grow underground, but eventually 

 come up to the surface of the ground, split open 

 and shed their spores* in the form of dust. 



I have already referred to the case of the common 

 Dandelion. Some plants, as we shall see, even 

 sow their seeds in the ground, but these cases will 

 be referred to later on. 



3. In other cases the plant throws its own seeds 

 to some little distance. This is the case with the 

 common Hairy Bittercress (fig. 63), a little plant, I 

 do not like to call it a weed, six or eight inches 

 high, which comes up abundantly on any vacant 

 spot in our kitchen gardens or shrubberies. The 

 seeds are contained in a pod which consists of three 

 parts, a central membrane and two side walls. 

 When the pod is ripe the walls are much stretched. 

 The seeds are loosely attached to the central piece 

 by short stalks. Now, when the proper moment 

 has arrived, the outer walls are kept in place by a 

 delicate membrane only just strong enough to 



* These are tiny seed-like bodies, but are termed " spores " by 

 botanists, because in some important points they differ from true 

 seeds. 



