374 PART IV. VEGETABLE TAXONOMY. 



continued downward into a long tap-root. From opposite sides, 

 just below the summit of the stem, arise two long, strap-shaped 

 persistent foliage leaves, several feet long, and usually more or 

 less fringed and torn at the apex, the only leaves the plant pos- 

 sesses, and from the circumference of the broad apex of the 

 stem, just above these, spring the branches of the cymose inflor- 

 escence. These arise from the axils of bracts, and are jointed 

 and dichotomously branching. See Fig. 573. 



The flowers in some species of the Gnetacese are monoecious, 

 in others dioecious, and both male and female flowers are invested 

 and protected by modified leaves, forming a kind of perianth 

 somewhat similar in character to that of the higher flowering- 

 plants. Each stamen bears either two or four pollen-sacs, the 

 ovules, like those of the higher plants, have two coats, and the 

 embryos are dicotyledonous. 



The members of the order, unlike the Coniferae, are destitute 

 of resinous secretions. 



CHAPTER XV.— The Spermaphyta (Continued). 



CLASS II.— THE ANGIOSPERM^E. 



The plants of this class greatly excel the preceding, and in 

 fact all others, in the number of their species, and in the variety 

 of their habits. There are probably not less than one hundred 

 thousand species, all told. They include the great majority of 

 our forest trees, and nearly all our shrubs, herbs, marsh plants 

 and flowering aquatics. A few among them have acquired para- 

 sitic or saprophytic habits, and are destitute of chlorophyll, but 

 these are the rare exceptions ; by far the larger part are chloro- 

 phyll-bearing. 



Their tissues are, on the whole, more complex than those of 

 Gymnosperms, and their vegetative organs, particularly the leaves, 

 are better developed. Their superiority is shown most conspic- 

 uously, however, in the structure of their flowers. The repro- 

 ductive organs — pollen-grains and ovules — are, as a rule, borne 



