PAPA VERA CEAE 69 



Osmia rufa Z. $> (9 mm.), Megachile centuncularis Z, S (6-7 mm.), and Apis mellifica 

 Z. (6 mm.), steal nectar through the holes bitten by humble-bees. Owing to the 

 smoothness of the petals the honey-bee loses a great deal of time while stealing nectar. 



150. D. eximia DC. The flower mechanism essentially agrees with that of 

 the last species, but there is less room for lateral movement of the hood, and the 

 path to the honey is shorter. (Cf. F. Hildebrand, Jahrb. wiss. Bot., Leipzig, vii, 

 1869-70, pp. 434-6.) 



151. D. cucullaria DC. The fiow*er possesses two long-spurred outer petals. 

 Nectar is secreted by two horn-shaped processes of the middle filaments, which 

 project into the spurs. (Cf. Hildebrand, op. cit., pp. 436, 637.) 



46. Adtumia Rafin. 



The flower mechanism resembles that of the last genus, but there is a larger 

 amount of fusion between the various parts. The pouches of the outer petals -are 

 smaller, and the edges of these petals are united together below. 



152. A. cirrhosa Rafin. Only the upper part of the hood is well developed 

 and free, while the lower part is fused with the outer petals. The six filaments 

 cohere below into a ventricose tube, (Cf. Hildebrand, op. cit., pp. 437-9.) 



47. Corydalis DC. 



Homogamous bee flowers. The hood can only be moved downwards. The 

 upper of the two outer petals is prolonged posteriorly into a nectariferous spur. 



153. C. cava Schweigg. et Koxt. (Hildebrand, op. cit.; Herm. Mtiller, 'Fer- 

 tilisation,' pp. 97-8; Kerner, 'Nat. Hist. PI.,' Eng. Ed. 1, II; Knuth, 'Bloemenbiol- 

 Bijdragen.') The spur of the rose-red or white homogamous humble-bee flowers 

 which exhale an odour of honey projects at the back for about 1 2 mm. beyond 

 the peduncle. A common process of the upper filaments thickened terminally 

 extends into it as far as the place where it bends. This process secretes nectar, 

 which is concealed in the downwardly curved end of the spur. The two inner 

 lateral petals are fused together at their tips, and cohere at their bases with the 

 two outer petals. The hood thus formed encloses the anthers and stigma. The 

 latter is large and lobed, and its surface is granular. It is situated on a rigid style 

 which cannot be bent down, and before the flower opens is covered with the pollen 

 of all the surrounding stamens, which readily adheres to its granular surface. The 

 empty anthers appear only as small appendages of the filaments beneath the stigma. 

 Insects long-tongued bees when probing for nectar, must insert their proboscis 

 between the hood and the upper spurred petal. In doing so they press down the 

 hood and in younger flowers dust their under-surface with the pollen which has 

 been shed on the stigma, and transfer it to the stigmas of older flowers that have 

 already been robbed of their pollen, thus effecting crossing. When the weight of 

 the insect visitor is removed the hood springs up by elasticity to its original position, 

 and again ensheaths the stigma. 



Although the stigma while within the hood is surrounded by the pollen 

 of the same flower, automatic self-pollination does not take place. Hildebrand has 



