378 



THE SEA SHORE 



Starting with the lowest of the melanospores, we first deal with 

 the order Ectocarpacece, which is characterised by olive, thread-like, 

 jointed fronds, with spores on the branchlets or embedded in their 

 substance ; two kinds of spores often existing in the same plant. 



The typical genus (Ectocarpus) contains many British species, 

 though several of them are rare. They are soft and flexible weeds, 

 generally of a dull olive colour, with slimy, tubular fronds, and 

 grow in tufts on other weeds or on mud-covered rocks. Spores of 

 various shapes are scattered over the fronds, and are also contained 

 in pod-like bodies formed of the branchlets. This latter feature is, 

 perhaps, the best distinguishing characteristic of the genus, but it 

 is not an easy matter to identify the several species it contains. 



E. tomentosus is very commonly found on Fucus and other 

 weeds, where it forms matted tufts of slender threads of a yellowish- 

 brown colour. The threads are clothed with transparent cilia, and 

 together form a dense, spongy mass. The spores are contained in 

 narrow pods supported on short stalks. E. littoralis is another 

 common species, of a very unattractive appearance. It grows in 

 matted tufts on other weeds, on rocks, mud, or any submerged 

 object, and its spores are contained in linear swellings of the branches. 

 This species thrives well in brackish water, and may be seen far up 



certain tidal rivers. 



Among the other species we may briefly 



mention E. granulosus, an abundant and beauti- 



FIG. 260. Ectocarpus FIG. 261. Ectocarpus FIG. 262. Ectocarpus 

 granulosus siliculosus Mertensii 



ful weed that grows in feathery tufts on rocks and weeds, with 

 elliptical, stalkless pods, quite visible to the naked eye, freely 

 distributed over the opposite branchlets ; E. siliculosus, a pale 

 olive, parasitic species with lanceolate stalked pods, pointed and 

 striped ; E. spheerophorus, a small, soft, brownish-yellow species, 



