SEAWEEDS AND THE WATER-FLORA. I9I 



streams, only opens its capsules in very wet weather; and 

 the seeds have a gummy secretion on the seed-coat, by 

 which they probably stick to the feathers of water birds. 

 Many water plants produce special buds before winter, 

 which are packed with starch or food material. These 

 drop off into the mud, and next year grow up into new 

 plants. 



The seashore is just as interesting as the margins of 

 lochs and rivers, but the life conditions are much more 

 complex, and they have not by any means been fully 

 investigated. 



There may be either (i) rocks, (2) shingle, (3) sand, 

 or (4) mud extending seawards from the edge of the 

 ordinary land vegetation. Each of these soils has its 

 own especial and peculiar series of plants, occupying 

 the space between the ordinary grasses or other vege- 

 tation and deep water. In every case, they tend to 

 choke themselves out by the accumulation of organic 

 matter which they produce, and are pushed further 

 and further seaward by the pressure of the advancing 

 land vegetation. As the sea often washes away the 

 land, and as estuarine rivers often eat into the banks, 

 obliterating the marks of succession, the exact succes- 

 sion is very difficult to trace, and is often obscured 

 altogether. 



Rock Flora. — Seaside rocks generally show a very 

 clear line, or division of plant life. Those parts which 

 are submerged at high tide are densely occupied by 

 Fucus, and sometimes by green Cladophoras and Entero- 

 morphas. Above high water mark, there is a regular 

 rock-flora, which, however, differs from the ordinary type 

 of rock-flora in the presence of characteristic lichens, 

 mosses, and flowering plants. The transitional plants 

 are mainly Algae and show the succession given above. 



