36 



A NATURALIST IN THE PACIFIC chap. 



amongst the plants of our beaches, each group bearing the impress 

 of an independent history :— 



(a) The plants of the beach and of the inland plain or of the 

 distant mountain peak, excluding those of the salt marshes. 

 Armeria vulgaris, Silene maritima, and Spergularia rubra may be 

 taken as examples. The currents here as a rule take little or no 

 part in their dispersal. 



(b) The " saline " group, including the plants of the saline plains 

 and the salt marshes of the interior of continents. Of these Glaux 

 maritima, Salsola kali, and Triglochin maritimum are examples. 

 The capacity of germinating in sea-water is a distinguishing 

 character of most of the plants ; and but few of them possess seeds 

 or seedvessels that are markedly buoyant. 



(c) The true beach plants that rarely stray far from the beach, 

 of which Arenaria peploides, Cakile maritima, and Convolvulus 

 soldanella are examples. Many of them have buoyant seeds or 

 fruits capable of dispersion over wide areas through the agency 

 of the currents. 



The reader will be able to extend this subject for himself if he 

 is so inclined, but we have gone far enough together to learn that 

 the plants with buoyant seeds or fruits are in the minority on our 

 beaches, scarcely a third of the total being fitted for dispersal by 

 the currents over broad tracts of sea. The British strand-flora thus 

 differs strikingly from the littoral flora of a Pacific island, or indeed 

 of any ordinary tropical coast, and in this respect it is to be 

 regarded as typical of the temperate regions. It has been re- 

 marked before that on a beach in the tropics we would expect 

 to find that quite three-fourths of the plants are provided with 

 buoyant fruits or seeds distributed far and wide over the tropical 

 seas by the currents. 



We pass on now to briefly discuss from the same standpoint 

 the British plants that find their homes on the borders of rivers 

 and ponds. It is here that the hygrophytes with buoyant seeds or 

 fruits gather together, just as the xerophytes with similar seeds or 

 fruits collect on the beaches. We have seen before that only a 

 portion of the beach plants belong to the buoyant group, and the 

 same applies to the plants at the edges of rivers and ponds. The 

 plant-formation is no more homogeneous there than it is in the 

 case of the strand-flora. Let us see if we can discern some lines of 

 division there also, or in other words let us endeavour to connect 

 the absence or presence of floating power in the fruits and seeds 

 with some variations in the placing of the plants. We still pursue 



