26 



Origin of the British Flora. 



main directions in which British plants are specially adapted 

 for dispersal are the following : — 



Modification. 



Abundance of minute seeds 

 (Heaths, Rushes, Saxi- 

 frages, Caryophyllacese, 

 &c). 



Abundance of large edible 

 seeds (Oak, Pine, Horn- 

 beam, Ivy, &c). 



Edible fruits with hard 

 stones (Blackberry, Haw- 

 thorn, Holly, Arbutus, 

 &c). 



Winged seeds (many Com- 

 posites, Willows, &c). 



Winged seeds with lax 

 hairs ( Willow - herbs, 

 Willows, Bulrush, &c). 



Burrs and hooked seeds. 



Floating seeds. 



Cut- leaved submerged water- 

 plants ( Water - crowfoot, 

 Water-milfoil, &c). 



Mode of Dispersal. 

 Readily moved by accidents 

 of all sorts. 



Eaten or dropped by birds ; 

 most are destroyed, but 

 some are transported un- 

 injured. 



Eaten by birds and mam- 

 mals ; seeds passed unin- 

 jured. 



Transported by wind. 



Cling to feathers or fur. 



Transported by water. 



Collapse and cling when re- 

 moved from the water ; 

 stems fragile, and broken 

 pieces grow. Carried on 

 legs of mammals or of 

 wading birds. 



The first group, the minute-seeded plants, is a very 

 large one, and it will readily be understood that the plants 

 belonging to it include nearly all the British species which 

 show strikingly anomalous distribution. Nearly all of our 

 Alpine plants, of the Lusitanian species found in Ireland 



