CHAP, v.] RELATIONSHIP AMONGST PLANTS. 173 



entering the resting stage. Alternation of generations 

 is often sharply marked. 



The following are the most important groups or 

 natural orders of Cryptogams : 



Seaweeds and their fresh-water allies (Algce) ; mush- 

 rooms, toadstools, puffballs, rusts, mildews, lichens 

 (Fungi) ; liverworts and mosses (Muscinece) ; ferns 

 (Filices) ; clubrnosses (Lycopodiacece) ; horsetails (Equise- 

 tacece) ; quillworts, salvinias, marsileas (Rhizocarpece). 



II. Phanerogamia. 



Sexual reproduction by oospheres that are fertilized 

 by passive or non-motile pollen grains ; these are brought 

 into contact with the oosphere by the agency of wind or 

 of insects, or the two sexes grow in immediate contact, 

 so that no external agency is required. The fertilized 

 oosphere by cell- division develops into a minute plantlet 

 or embryo while still inclosed within its protective 

 covering, the whole constituting the seed, which at 

 maturity enters the resting stage. Asexual reproduction 

 by spores. Alternation of generations absent. 



To the present section belong all plants not enume- 

 rated under the preceding section, and popularly known 

 as flowering plants, on account of the usually conspicuous 

 flower; nevertheless, in very many phanerogams the 

 flower is comparatively inconspicuous, or very minute 

 and entirely devoid of colour, as in the grasses, sedges,, 

 and many forest trees. 



In connection with the classification of plants, it is of 

 the greatest importance to bear in mind the fact that 

 the characters of sections given in books do not include 

 all the important features presented by the members 



