Seasides and Strand Plants 



These are the joints of Salicornia herbacea, the salt- 

 wort or marsh samphire, whose seeds germinate in salt- 

 water (indeed they are more healthy in it than in 

 fresh), and whilst still attached to the buoyant, cigar- 

 shaped joint.* 



One of these seedling plants grounds in the salt mud 

 on the top of the bank, and its roots at once grow 

 vigorously, and very soon a small independent plant has 

 established itself. Others no doubt accompany it, and 

 the surface of the bank is soon overspread with this 

 remarkable plant. It is extremely like a miniature 

 cactus, and this succulence seems inexplicable, for why 

 should it resemble a desert plant when it has water every- 

 where, and indeed is daily submerged at high tide ? 



But the water is salt, and common salt is really a 

 poison to vegetable protoplasm. The Salicornia, how- 

 ever, has adapted itself to these conditions ; it can alter 

 the density of its internal cell sap and so regulate the 

 amount of water taken in. 3 It has been found that the 

 protoplasm of its root-hairs is healthy in so concentrated 

 a solution as 5.8 per cent, of common salt. If, however, 

 the root-hairs are left for two hours in 1 per cent, solu- 

 tion, and then suddenly transferred to a 5.8 solution, 

 the protoplasm shrinks together (or is plasmolysed). 4 



This little experiment shows that it is able to regulate 

 the density of its cell sap according to the saltness of 

 the water, and so explains how it has been able to adapt 

 itself to these dangerous conditions. 



One might compare its behaviour to that of people 

 who accustom themselves to the eating of arsenic, and 

 gradually become so trained to the poison that indeed 

 they can hardly do without it. 



* Dr. Guppy 2 found joints with fruits and apparently germinating seedlings 

 off the coast of Peru. The seedlings in salt-water can live for some ten weeks 

 but then die if they cannot attach themselves to salt mud. 



l6o 



