90 ANGIOSPERMAE—DICOTYLEDONES 



nordfr. Ins.,' p. 23, ' Bloemenbiol, Bijdragen.') — The large violet flowers exhale 

 a strong odour of violets, especially in the evening. Two large green fleshy nectaries 

 surround the bases of the short stamens, and are especially well developed internally. 

 The nectar collects on either side of the flower between the insertions of the stamens 

 and the base of the pistil. The anthers of the long stamens stand in the throat of 

 the corolla ; after dehiscence they grow somewhat and project beyond the flower. 

 When the anthers of the short stamens dehisce, their lower parts come into contact 

 with the stigma, which during anthesis grows so as to project out of the flower. The 

 anthers dehisce introrsely, so that all of them can pollinate the stigma, automatic 

 self-pollination being therefore inevitable. Insects sucking nectar regularly effect 

 cross-pollination, however, for they touch stigma and anthers with opposite sides 

 of their proboscis or head. In the case of those which collect pollen the chances 

 of cross- and self-pollination are equal. 



Warnstorf says that the flowers vary from slightly protogynous to homogamous. 

 The pollen-grains are pale yellow, closely and finely tuberculated, and ellipsoidal, 

 measuring up to 37 fL in length and 25 jx. in breadth. 



Visitors. — The following have been observed by Hermann Miiller (H. RL), 

 Borgstette (B.), Buddeberg (Budd.), and m_vself (Kn.). — 



A. Coleoptera. Telephoridae: i. AnthocomusfasciatusZ. (H. M.). B. Diptera, 

 {a) Siraiiomyidae : 2. Nemotelus pantherinus Z., po-dvg. (H. M.). (3) Syrphidae: 

 3. Chrysogaster aenea Mg., po-dvg. (B.); 4. Eristalis arbustorum Z., po-dvg. (Kn.) ; 

 5. E. nemorum Z., po-dvg. (H. M., B.) ; 6. E. pertinax Scop., po-dvg. (Kn.) ; 7. E. 

 tenax Z., po-dvg. (H. ]M., Kn.) ; 8. Rhingia rostrata Z., very freq., skg. and po-dvg. 

 (H. M., Budd., Kn.) ; 9. Volucella pellucens Z. (B.). C. Hymenoptera. Apidae: 

 10. Andrena albicans MUll. }, po-cltg. (H. M.); 11. Apis mellifica Z. 5, po-cltg. 

 (H.M., Kn.); 12. Bombus lapidarius Z. 5, ditto (Kn.) ; 13. Halictus leucopus A'. 5, 

 po-cltg. (H. M.). D. Lepidoptera. 14. Pieris brassicaeZ., freq,, skg. (H. M., Kn.); 

 15. P. napi Z., ditto (H. M., Kn.); 16. P. rapae Z., ditto (H. M., Kn.); 17. Vanessa 

 urticae Z., skg. (Kn.). 



210. H. tristis L. (Harm. Mullcr, ' Weit. Beob.,' II, pp. 200-2 ; Kerner, 

 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 208.) — This species bears homogamous moth- 

 flowers. The petals are of a dirty greenish-yellow, and traversed by a network of 

 delicate dirty grey-green veins. They are therefore not very conspicuous among 

 the foliage, although their spreading limbs are 14-20 mm. long, or even more, 

 3-iid 3-5-| mm. broad. During the daytime there is no marked scent, and scarcely 

 any insect visitors. Between seven and eight o'clock in the evening, however, the 

 blossoms open and exhale a powerful and agreeable odour — of hyacinths, according 

 to Kerner — after the fashion of moth-flowers. 



On the inner side of the bases of the short stamens — according to Hermann 

 Miiller's account — there are two large green fleshy nectaries, the secretion of which 

 is so abundant that it completely fills on each side the angle between the base 

 of the short stamen, the two adjacent long stamens, and the pistil. 



The narrow sepals are 11-15 mm. long. Their basal parts curve slightly 

 outwards, but their upper two-thirds are so closel}' apposed as to hold the claws 

 of the petals firmly together. At the beginning of anthesis there are thus but one 

 or two narrow passages to the nectar, which are only adapted to the proboscides 

 of Lepidoptera. When the flowers open the pollen-covered anthers of the four 



