CHAPTER XXVIII. 



THE GYMNOSPERM.E. 



THE Anthophyta are divided into two classes, the Gymno- 

 spermte, in which the ovules and seeds are not inclosed in an 

 ovary, and the Angiospermse, in which the ovules and often the 

 seeds are inclosed in an ovary. 



The AngiospermaB are divided into two subclasses, the mono- 

 cotyledons, in which the embryo has one cotyledon, and the 

 plants generally have parallel veined leaves, and the numerical 

 plan of their flowers is three ; and the dicotyledons, in which the 

 embryo has two cotyledons, and the plants generally have netted 

 veined leaves, and the numerical plan of the flowers is five. This 

 subclass includes the greater part of plants and trees of the tem- 

 perate zones. 



The gymnosperuise all have woody stems, and generally nar- 

 row, needle-shaped, parallel veined leaves. The members of this 

 class are mostly trees, including the redwood, pine, spruce, cedar, 

 fir and cypress. The male and female organs are in different 

 flowers, which are very simple, consisting of one or more stamens 

 in the one case, and naked ovules in the other. After fertilization 

 the embryo, consisting of root, stem and leaves, is soon formed. 

 The various parts of the reproductive organs are homologous 

 with those of the pteridophyta, the material from which the em- 

 bryo sac and embryo are developed corresponding with the 

 prothallium. 



A careful study of the Scotch or the Austrian pine will give us 

 clearer ideas of the whole class than to spend the same amount 

 of time on several members of the group. 



The Scotch pine is a species often planted for ornament. The 

 leaves, from two to four inches long, occur in pairs, and are cov- 

 ered with a whitish powder which gives a peculiar color to the 



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