THE ANGIOSPERMAE 



1317 



visits anything else. Scrophidaria nodosa is almost universally visited by 

 wasps and by few other insects. We shall deal with such examples later when 

 considering the types of flowers suited to particular groups of insects. 



Among the actinomorphic flov^ers with concealed nectar we may cite 

 the following: Trollhis, Malva, Riibus, Oxalis, Eptlobium, Ricinus, Myosotis, 

 Vaccinium, Calhina and many others, while among the countless zygomor- 

 phic types are nearly all the Labiatae, and many members of Scrophulari- 

 aceae and Orchidaceae as well as other families. 



As an example of the actinomorphic type of flower we may describe 

 Vaccinium myrtilliis (Fig. 1235). The flowers are pendulous and bell-shaped, 

 greenish in colour with a pink or red tinge and completely lacking in scent. 



Fig. 1235. — Vaccinium myrtilliis. A, Flowering shoot. B, Vertical section 

 of flower during pollen discharge. C, External view of flower show- 

 ing unexpanded stigma. D, Vertical section of flower in female 

 state, with expanded stigma. E, Single stamen. F, Flower with 

 calyx after abstriction of corolla and stamens. 



Despite their inconspicuous nature they are very rich in nectar and are 

 sought after by bees. The corolla is made up of five petals which are fused 

 together, except at the tips, to form a bell into which only a fairly long- 

 tongued insect can thrust its proboscis with a hope of reaching the nectar. 

 The centre of the opening is partly blocked by the capitate stigma. An 

 insect trying to enter the flower will therefore touch the stigma with its head. 

 The flowers are protandrous and the stamens are situated around the style 

 in the lower part of the flower. Each stamen consists of a short curved 



