166 STSTEMATIG BOTANY. 



ANGIOSPERM^. 



184. The second class of the Phsenerogamia, namely, 

 the Angiosperms, have ovules enclosed in an ovary ; 

 they are further distinguished from the Gymnosperms in 

 having, as a rule, much more complex flowers. They are, 

 in the great majority of cases, monoclinous (or hermaphro- 

 dite) ; that is, the male (staminate) and female (pistillate) 

 organs occur in the same flower. The floral axis generally 

 remains very short ; at its centre or top is situated the 

 gynceeium, as the pistils are collectively called, and imme- 

 diately below, or without this whorl, is the whorl or whorls 

 of stamens, which are denominated the androsdum. Sur- 

 rounding these organs closely is generally found the 

 perianth, consisting of one (calyx) or more (calyx and 

 corolla) whorls of modified leaves. The latter are usually 

 conspicuous and attractive (in entomophilous flowers) on 

 account of size, color, odor, or honey secreted in the 

 nectaries, which are usually present at their base. The 

 pollen grains, transported from the anthers by various 

 agencies to the viscid stigma, there germinate, or send 

 down a tube through the loose tissue of the pistil which 

 enters the micropyle of the ovule, and effects the fertiliza- 

 tion of the latter. 



185. The effect of fertilization is manifest as follows : 

 The germ-cell (called also the embryonic vesicle), situated 

 in the apical region of the embryo-sac, at once develops a 

 cellulose-wall. It then divides transversely one or more 

 times, giving rise to a row of cells, called the suspensor, 

 or proembryo, and the lower end of this, by copious cell- 

 multiplication, forms the embryo. There is, in the mean- 

 time, " free cell-formation" of the protoplasm in the basal 

 portion of the embryo-sac, by which the endosperm is 



