158 



SYSTEMATIC BOTANY. 



269) are the stamens (Fig. 269, sta), which produce (in the 

 anthers) the pollen grains, the latter homologous with the 



microspores; and the pistils 

 (Fig. 269, P), in which (ovary) 

 the ovules are produced, which 

 contain the embryo-sacs corre- 

 sponding to the macrospores of 

 the previous division. Enclos- 

 ing and protecting these often 

 grow special organs (slightly 

 modified leaves), called the 

 perianth ; or, when two whorls, corolla (Fig. 269, eor), and 

 calyx (Fig. 269, cal). These, together with the stamens 

 and pistils, and also the axial structure which bears them 

 (Fig. 269, torus), constitute the Flower, whose development 

 in general is as follows : At the end of a stem, protected 

 and concealed by the small leaves, called bud-scales, arise 

 minute papillse, or elevations, forming a peripheral whorl 

 (Fig. 270). These are the first development of the outer- 

 most floral organs, namely, sepals (Fig. 270, «). Imme- 

 diately following them appear another whorl of similar 

 papillae (Fig. 271), situated within the first, and these 

 represent the petals (Fig. 271, P). These two sets grow 

 rapidly, arch over, and protect the essential organs which 

 develop within. 



i8o. While the two "/f.^»^ f k^ el 

 whorls described above 

 are increasing in size, 

 a third whorl of papillae 



Fig. 269, Longitudinal section of a flower ; cat calyx ; ear, corolla ; se^, sepals ; 

 ^ei, petals ; sia, stamens ; /, pistil ; torus, torus : pedun, peduncle. Figs. 270- 

 273. Diagrammatic representations of the successive stage's in the early develop- 

 ment of a flovrer ; s, sepals ; /, petals ; an, stamens ; p, pistil. 



