MORPHOLOGY OF HIGHER PLANTS. 



403 



the rose; glandular and non-glandular hairs are also developed 

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

 vandula vera 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 i'nner 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 



