DEVELOPMENT OF PLANTS 



479 



muscular insect alighting upon the knobbed lower lip to force 

 his way into the flower. It is worth any one's time to sit by 

 this plant and examine the mechanism of the flower while the 

 bee is at work. The sporophylls present the same variety of 

 arrangements for crossing as noted in the mints. The nectar 

 glands are situated at the base of the carpels but the nectar does 

 not remain upon the glands as in the majority of flowers, but 

 runs down through a narrow duct between the filaments and 

 collects in the spur-like prolongation of the corolla (Fig. 333, 5). 



FIG. 333- Examples of the Figwort family: A, inflorescence of the toad- 

 flax (Linaria). B, flower viewed from beneath, showing the under lip arching 

 up against the upper, two-lobed lip s, nectar spur of the corolla. C, section 

 of the flower viewed from the side, showing the undivided ovary with central 

 ovules. Note the stigma and anthers concealed at the lips of the corolla. 

 D, sectional view of flower of Rhinanthus with the four stamens arranged 

 in pairs. E, appearance of the stamens as viewed from the mouth of the 

 corolla. The filaments have been pressed apart, thus separating the opened 

 anthers. 



The yellow rattlebox (Rhinanthus, Fig. 333, D, E) shows an- 

 other form of the flower, common in this family. The general 

 arrangement of the floral organs is the same as in Linaria, but 

 the anthers are in pairs so that when they open, owing to the 

 rigidity of the filaments or the pressure of the upper lip, they 



