586 



BOTANY 



PART II 



with scaly hairs ; in Pinus sylvestris the fall is seven times and in Pithecoetenium 

 thirty times slower. 



The distribution of seeds and fruits by ocean currents is important for many 

 plants. The strand-flora of the Malayan Archipelago, for example, consists, accord- 

 ing to SCHIMPER'S investigations, exclusively of plants with floating fruits or seeds, 

 the adaptations of which correspond more or less to those of the Coco-nut (Fig. 821) 

 which is distributed everywhere on tropical coasts. A thick exocarp consisting of 

 a coarsely fibrous tissue renders the fruit buoyant and protects the brittle and stony 

 endocarp from being broken against the rocks and stones of the shore. A very 

 similar structure is exhibited by species of Barringtonia, Cerbera Odollam (Fig. 

 576), Terminalia catappa, Nipa fruticans, and many smaller plants belonging to 



the shrubby and herbaceous 

 vegetation of the dunes and 

 strand. In all cases the 

 capacity of floating for a long 

 time is a condition of the dis- 

 tribution of the seeds and the 

 success of the species. - 



The distribution of fruits 

 and seeds by means of animals 

 depends as a rule upon the 

 succulent and attractive fruits 

 serving as food for birds, the 

 undigested seeds being shed. A 

 familiar example is afforded by 

 the Elder (Sambucus nigra), 

 the black fruits of which are 

 eaten by various birds in 

 summer. There are many such 

 cases, arid for some seeds the 

 passage through the intestine 

 of the animal appears to be a 

 necessary preliminary to ger- 

 mination. The development of 

 The an arillus (cf. p. 582) is in many 

 cases an adaptation to distribute 

 the seed by means of animals. 

 The arillus of Taxus with its 

 bright red colour which surrounds the single seed is greedily eaten by blackbirds ; 

 the red fruits of Euonymus when they open expose four seeds with bright red arilli, 

 which are eaten by chaffinches. The Nutmeg is distributed over the islands about 

 the Moluccas by a large pigeon which is attracted by the bright red arillus around 

 the black seed which is exposed on the dehiscence of the fruit. In a similar way our 

 Mistletoe in winter, when little other food can be obtained, is eaten by blackbirds 

 and other birds ; when the birds clean their beaks the seeds remain attached to the 

 branches by reason of the viscid substance around them and are able to germinate 

 in this position. The spread of plants with hooked fruits, etc., such as Galium 

 aparine, species of Lappa (cf. Fig. 781), Bidens, Xanthium, etc., by means of the 

 fur of quadrupeds, the general distribution of water-plants from one pond to 

 another by aquatic birds, and the distribution of the Hazel-nut, etc., by means 

 of squirrels, do not require detailed description. Lastly, the distribution of certain 



FIG. 576. Fruit of Cerbera Odollam, from the drift. 



succulent endocarp is wanting, so that the buoyant tissue 

 traversed by coarse fibrous strands is exposed. (After 



SCHIMPER.) 



