Seasides and Strand Plants 



nearly horizontal ; the men also tend to form an acute 

 angle with the rope. The stem and roots of Zostera 

 has a curious similarity to the tug-of-war rope, and one 

 sees at once how well it is adapted to hold its place. 



All along the stem, at every i or 2 inches, are the 

 flattish, grass-like leaves which may be 3 feet long, 

 and are kept upright and waving in the water. These 

 leaves have a water-pore at the tip (presumably to keep 

 up the circulation of food material), but are without 

 the stomata characteristic of ordinary leaves. 



The flowers consist of one stamen and one carpel, and 

 about twelve of them are enclosed in a protective sheath. 



When ripe, the pollen is discharged into the water. 

 The whitish pollen grains resemble tiny worms about 

 3 mm. long (-^^th inch ; the length is about 250 times 

 the breadth), and are unlike any other pollen grains. 

 Being of the same specific gravity as sea-water, they 

 float freely about ; should they happen to touch the 

 long stigmatic surface of a carpel, they wrap themselves 

 spirally round it and so effect fertilisation. The fruit 

 is supposed to be eaten by fish. If so, Zostera marina 

 has been successful enough, for it is found from the 

 Mediterranean to the Baltic, in North America (Atlantic 

 and Pacific Coasts), and in China and Japan.^ 



These submerged meadows are of some importance, 

 for they tend to prevent the continual shifting of the 

 sand- and mud-banks, which of course is the first step 

 in the formation of new land. How far they succeed 

 in doing this has not as yet been discovered. 



When, however, such banks have been fixed in position 

 and so raised by deposited silt that they are distinctly 

 exposed at low water, a new development begins. 



Amongst the floating rubbish carried back and forward 

 by the changing tides are certain round fleshy little 

 bodies bearing minute flowers and fruits. 



159 



