194 PLANT LIFE. 



possible here to give a very satisfactory account of 

 the succession. 



The Seagrass {Zosterd) covers hundreds of acres at 

 Hunterston Point on the Clyde, and must be considered 

 as perhaps the most important of all these land- forming 

 plants ; for it is the Zostera which is probably the first 

 to fix definitely the mudbanks of navigable rivers, 

 though the important practical questions which arise 

 from this fact are not yet answered. It extends to a 

 depth of 36 or even 42 feet, and forms a sort of sub- 

 marine meadow ; the leaves are long and like those of 

 grasses, and are said to become much broader at great 

 depths ; the rhizomes from which they spring form a 

 sort of interlacing entanglement on the mud, and occur 

 in great quantity. 



Another plant, Euppia, which is abundant at 

 Cardross upon the Clyde, occurs nearer the shore 

 generally from a little below high-water mark to a 

 considerable depth. It has a creeping stem or rhizome 

 of a very peculiar appearance. There are generally 

 from three to four internodes (about half an inch long) 

 of which the two or three oldest are completely buried 

 in the mud ; this covered part curves downwards so as 

 to lie below the small exposed portion. A root 3-4 

 inches long is given off at every node. The internodes 

 of the stem are not in line with one another, but zigzag 

 alternately to right and left, and the roots therefore 

 slant downwards also to right and left. The peculiar 

 anchorlike curve of the stem, tied down by these 

 relatively long roots, will offer a very strong resistance 

 to the uprooting effect of the currents. One long, thin 

 and grasslike leaf is also given off from each node. 



The mud-flora is especially characterised by such 

 plants as Cochlearia, Plantago maj^itima, Aster Tri- 



