MORPHOLOGY OF HIGHER PLANTS. 



403 



the rose; glandular and noivglandular hairs are also developed 

 which are peculiar to the corollas of irregular flowers, as in La- 

 vandula vcra and Viola tricolor (Figs. 124, 149-155, 232) ; 

 stomata are comparatively few in number. The epidermal cells 



FIG. 232. Inner morphology of the flower as illustrated in Viola tricolor. A, epider- 

 mal cells from the outer surface of the spurred petal showing papillae; B, epidermal cells 

 from the under surface of the petals, some of the cells showing centripetal thickenings, the 

 two without thickenings indicating the epidermal mucilage-cells; C, epidermal cells from 

 the under surface of the petals showing a zigzag outline and short centripetal thickenings; 

 D, surface view of the mesophyll of the petals; E, corkscrew-like hair from the inner sur- 

 face of the spurred corolla near the throat; F, a hair from the edge of an anther; G, epider- 

 mal cells of the anthers; H, surface view of the mesophyll cells from the spurred stamen 

 showing collenchymatous thickening; I, surface view of cells of endothecium; K, pollen 

 grain viewed from the side; L, pollen grain examined in water; M, pollen grain observed 

 in chloral solution. 



are but slightly cutinized, and in surface view are strongly undu- 

 late and appear striate owing to the papillose development (Figs. 

 232 and 235). The chlorenchyma is made up of rather loose, 

 branching parenchyma cells (Fig. 232, D), with large, intercellular 

 spaces. The cells are free from chloroplastids, may contain 



