DIVISIONS OF FLOWERING PLANTS 179 



marked feature of the vegetation of Central America 

 and Australia. 



From what has already been stated we are now in a 

 position to define the Phanerogamia, or Flowering plants, 

 as forms of plant-life in which the asexual generation, 

 or sporophyte, is cormophytic (Gr. Jcormos, the lopped 

 trunk of a tree) — i.e., it has a definite axis of growth; 

 it assumes various forms and produces two kinds of 

 spores — the male pollen grain (microspore) and the 

 female embryo-sac (megaspore). The alternation of 

 generations, so prominent in the Archegoniates, is ob- 

 scured in the Phanerogamia by seed-formation. The 

 megaspore remains in the sporangium (ovule) throughout 

 its development, and the ovule ripens into a seed. The 

 pollen grain (microspore) produces a pollen tube, and 

 a single cell, which divides into two generative cells 

 (male elements), represents the antheridium. In the 

 Cycads, the lowest plants of the division, the generative 

 cells become swimming spermatozoids. 



The Phanerogamia are subdivided into the Gymno- 

 sperms and the Angiosperms, and there is a distinct 

 difference between the two subdivisions. In the Gymno- 

 sperms (Gr. gymnos, naked; sferma, seed) the ovules are 

 not enclosed in an ovary, but occur naked, or exposed, 

 on a scale, or open carpel ; they receive the pollen direct 

 into the micropyle. The Angiosperms (Gr. angeion, a 

 case) have their ovules enclosed in an ovary formed of 

 coherent carpels, or of one carpel with its margins co- 

 herent; the pollen is received on a stigma, which does 

 not occur in the Gymnosperms. The Angiosperms, now 

 so prevalent and so numerous in species, are, according 



