522 



BOTANY 



I'AKT II 



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 which is 

 distributed everywhere on tropical coasts. A thick exocarp consisting of a coarsely 

 fibrous tissue renders tlie 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, Cerhera Odollam (Fig. 493), 

 Terminalia catappa, Nipa fruticans, and many smaller plants belonging to the 

 shrubby and herbaceous vegetation of the dunes and strand. Others have large 

 air-spaces in the pericarp or seed-coat, which being protected from the entrance 



of water, serve as swimming- 

 bladders. 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 

 succvdent and attractive fruits 

 serving as food for birds, the 

 undigested seeds being shed. 

 A familiar example is afl'orded 

 by the Elder (Sambucus nigra), 

 the black fruits of which are 

 eaten by various birds in sum- 

 mer. There are many such 

 cases and for some seeds the 

 passage through the intestine 

 of the animal appears to be a 

 necessary preliminary to ger- 

 mination. The development 

 of an arillus (cf. p. 517) is in 

 many cases an adaptation to 

 distribute the seed by means 

 of animals. The arillus of 

 Taxus with its bright red 



bright 



the single 



Fig. 493.— Fruit of CcvliKra Odollam, from tlie drift. The 

 succulent endocarp i.s wanting, so that tlie buoyant tissue 

 traversed by coarse fibrous strands is exposed. (After 



SCUIMPER.) 



. colour surrounds 



seed, which is not poisonous and is greedily eaten by blackbirds ; the red fruits 

 of Euonynms w'hen they open expose four seeds with bright red arilli, which 

 are eaten by cliafiinches. 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 wlii(!h is exposed on the deliiscence 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 tliem and are able to ger- 

 minate in tills position. Since germination does not occur in other situations the 

 viscid fruits of this plant are indispensable to its success. 



The spread of jjlants with hooked fruits, etc., such as Galium a2mrine, species of 

 Lappa, Bklens, Xanlhium, etc., by means of the fur of quadrupeds, the general 



