126 THE PLANTS 



B.— Fixed Plants. 



BY MRS. DR. A. WEBER — VAN BOSSE. 



After a storm heaps of plants are cast ashore by the 

 sea, especially if the coast is rocky. On closer exam- 

 ination, these entangled masses are found to consist 

 of green, brown, purple, or bright red plants. 



What are these ? Where do they live ? 



These bright-coloured plants are algae, or flowerless 

 plants, distinguishable by their colour and various 

 shapes from marine flowering plants ; the latter have, 

 as a rule, narrow, long, linear leaves of a dark green 

 colour, as, for instance, the common sea grass, Zostera 

 marina, so well known on English coasts. 



This section treats only of attached or fixed marine 

 algae, not of the (mostly microscopical) drifting algae 

 belonging to the plankton. A few words will be said 

 of algae growing in brackish water, its interesting flora 

 showing the influence of the changing medium ; for 

 some marine algae migrate through brackish water into 

 fresh water, which has, besides, a rich flora of its own. 



Algae can assume the most different shapes ; their 

 fronds may be either simple or branched filaments 

 (Chaetomorpha, Cladophora, Polysiphonia), or ex- 

 panded membranes of various colours, composed of 

 one or more layers of cells (Monostroma, Ulva, Por- 

 phyra) ; they may have the form of a smaller or larger 

 bush with stem and branches (Splachnidium, Des- 

 marestia, Delesseria) ; or look like a delicate bit of lace 

 (Vanvoorstia, Claudea) ; or be composed of a long, 

 flexible stalk, bearing long linear blades at its swollen 

 top (Ecklonia buccinalis). Again, others form crusts, 

 adhering closely to the substratum (Ralfsia, Hilden- 



