PLANTS FOR THE AQUARIUM 85 



which cover the shore rocks with their long, slender, grass-like 



fronds, sometimes branched and sometimes unbranched. Much 



prettier are the species of Cladophora, which are all copiously 



branched and bushy, often with very rigid branchlets. In the 



graceful little Bryopsis plumosa, which consists of a number of 



branches rising from a common base, each branchlet is delicately 



feathered, usually near its summit only, 



but sometimes nearly to the base. If 



it is desired to attempt to add a red 



alga for the sake of the colour, one of 



the best is perhaps Phyllophora rubens, 



a small form characterised by its fine 



red colour, and by the leafy lobes which 



it throws out at the extremity of its 



flattened branches. Further details in 



regard to the marine algae will be found 



in Grattan's British Marine Algce 



(London, n.d.). 



Freshwater algae are not uncommon ; 

 some forms grow freely on damp earth 

 or float near the surface of ponds, but 

 we need only notice Chara and its allies. 

 These are the highest of the algae, and 

 mimic flowering plants in appearance. 

 They occur in ditches and ponds, and 

 are especially common in the Norfolk 

 Broads. In Chara fragilis the plant 

 reaches 12 inches in length, and is fixed 



into the mud by the so-called roots. The FlG . 4a _ A freshwater green alga 

 stem grows upright in the water, and 

 bears whorls of slender leaf-like organs 

 at the nodes. The whole plant is delicate 

 and slender. Some species have a protective deposit of carbonate 

 of lime on their surface, and some have a strong and disagreeable 

 odour. On the leaves are borne the reproductive organs, the male 

 being bright red, spherical and minute, while the female are larger 

 and flask-shaped. They are at first reddish and afterwards become 

 black, drop off the plant, and remains inert until the next spring, 



(Chara fragilis). The dots on 

 the whorled leaves are the re- 

 productive organs. 



