210 PRACTICAL BOTANY 



CHARACE^: 



Various members of this family are found growing in stagnant, 

 or slowly flowing fresh water : they are green, but owing to 

 superficial lime incrustations, they may appear white and chalky, 

 especially when dry : they are brittle in texture, and are 

 commonly called Stone-Worts. They grow rooted in mud, and 

 put up into the water a branched shoot, which may be a foot or 

 more in length : this bears at intervals whorls of lateral 

 appendages the "leaves." In summer and autumn these 

 bear the sexual organs in large numbers, the antheridia being 

 specially prominent owing to their bright red colour. The 

 odour of these plants is characteristic, being like that of 

 onions. 



There are two chief genera of the family, viz., Chara and 

 Nitella (besides other subgenera) : the most obvious difference 

 between these is that Chara is more robust, the stem and leaves 

 having a peripheral cortex, while Nitella has none. A large 

 number of species are distinguished, and as it might be difficult 

 for beginners to recognize any one definite species with certainty 

 from others, the description given below will be confined to the 

 more essential characters of the genus Chara, while Nitella 

 will be dealt with only incidentally. Fresh material should be 

 used if possible ; most of the structural points can, however, 

 be successfully observed on material preserved in alcohol. 



I. Examine a mature specimen of Chara with the naked eye, 

 or with a pocket lens, and note 



i. The stem^ which is as thick as coarse packthread, and is 

 marked off into internodes of length varying from I to 3 or 4 

 inches : this axis is of unlimited growth, and is terminated by 

 an apical bud. 



