128 MORPHOLOGY 



the fact that even in homogamous flowers nature has 

 made a provision for preventing self-pollination and 

 securing cross-pollination. Most Papilionacece, Vio- 

 lacece, Labiatce, and Orchidacece belong to this class. 

 It is interesting to observe that flowers with a corolla- 

 tube of horizontal attitude have always a large under 

 lip, which is either brightly coloured or provided with 

 nectar-guides. Such flowers are evidently elaborated 

 for the visits of bees. Butterflies, as a rule, cannot 

 rest upon the large under lip or platform, in conse- 

 quence of their upright wings, whereas bees find a 

 j0ST,„,:^^:,,t-^ comfortable seat there. Small 



(!i^'^^fei''4''i'''v insects are usually prevented 



^'^^^^^^^^^^^;,,_3 from entering by hairs sur- 



^^^feP'-^^rO rounding the throat of the 



^^^^^lA I.. corolla -tube (fig. in). In 



— Goldfussia {Strobilanthes), a 



^\siroMaMeT^ common garden annual, the 



bee alights upon the platform, 

 and, directed by the nectar-guides, walks into the tube 

 in quest of honey concealed deep down. Immediately 

 on entering, the curved-up style {a) makes a salaam to 

 the bee by straightening itself and then curving down- 

 wards {b). When busy sucking honey, the belly of 

 the bee becomes coated with the pollen-grains, which 

 she carries with her to the next flower and rubs the 

 pollen-grains she has brought with her upon the 

 curved-up style of the latter, which then, at the touch 

 of the bee, straightens and curves down, as described 

 above. This motion of the style prevents the bee from 

 depositing the pollen of a flower upon the stigma of 

 the same flower while she recedes and leaves the latter. 

 The flowers of bakas {Adhadota Vasica) (fig. 112), 

 with a bilabiate corolla, are vertical and often visited 

 by butterflies, but, on account of an erect large upper 



