

PAPA VERA CEAE 65 



effect either kind of pollination. During dull weather the flowers remain closed for 

 a long time, in which case the anthers dehisce in the bud and effect self-pollination. 

 Warnstorf describes these flowers as varying from slightly protogynous to homo- 

 gamous, and from this to protandrous. The pollen-grains are of a beautiful yellow 

 colour, rounded, finely tuberculated, and measuring up to 37 /a in diameter. 



Visitors. These are chiefly insects vainly seeking for nectar, and next to 

 them come pollen-collecting bees and pollen-devouring flies. The larger bees 

 (humble-bees and the honey-bee) alight as a rule on the middle of the flower, thus 

 effecting cross-pollination, while smaller forms (species of Halictus) usually settle 

 on the edges of the blossoms, and only occasionally touch the stigma, in which case 

 either kind of pollination is equally probable. Hover-flies behave in the same way. 



The following visitors have been determined by Hermann Miiller (H. M.) in 

 Westphalia, and by myself (Kn.) in Schleswig-Holstein. 



A. Coleoptera. (a) Chrysomelidae : I. Cryptocephalus sericeus Z., po-dvg. 

 (Kn.). (5) Nilidulidae : 2. Meligethes, po-dvg. (H. M.). B. Diptera. (a) Empidae: 

 3. Empis livida L., vainly searching for nectar, or perhaps boring (H. M.). (b) Syr- 

 phidae: 4. Ascia podagrica F., po-dvg. (H. M.); 5. Eristalis arbustorum Z., po-dvg. 

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

 8. Helophilus pendulus Z., po-dvg. (Kn.) ; 9. Melanostoma mellina Z., po-dvg. (Kn.^ ; 

 10. Melithreptus taeniatus Mg., po-dvg. (Kn.) ; 11. Rhingia rostrata Z., first vainly 

 searching for nectar, then po-dvg. (H. M.^ ; 12. Syritta pipiens Z., po-dvg. (H. M^ ; 

 13. Syrphus balteatus Beg., po-dvg. (H. M., Kn.) ; 14. S. ribesii Z., po-dvg. (H. M., 

 Kn.). C. Hymenoptera. (a) Apidae : ifi. Anthophora pilipes F. 5, po-cltg. (Kn.) ; 

 16. Apis mellifica Z. jjj, po-cltg. (H. M., Kn.) ; 17. Bombus agrorum F. $f, po-cltg. 

 (H. M., Kn.) ; 18. B. hortorum Z. 5, po-cltg. (Kn.) ; 19. B. lapidarius Z. , po-cltg. 

 (Kn.) ; 20. B. pratorum Z. $, po-cltg. (H. M.) ; 21. B. rajellus K. 5, po-cltg. (H. M.) ; 

 22. B. terrester Z., po-cltg. (Kn.). Herm. Miiller noticed that humble-bees settle on 

 the middle of the flower, sweep pollen very rapidly from the anthers with the tarsal- 

 brushes of the first two pairs of legs, and immediately transfer it to the ' baskets ' of 

 the hind-legs, completing the operation in from two to three seconds, and then 

 at once flying away to another flower to treat it in the same fashion, thus effecting 

 cross-pollination. 23. Halictus cylindricus F. 5 (H. M.) ; 24. H. sexnotatus K. $ 

 (H. M.) ; 25. H. sexstrigatus Schenck 5 (H. M.) ; 26. H. zonulus Sm. 2 (H. M.) ; these 

 four species of Halictus fly to the anthers to collect pollen, occasionally touching 

 the stigma. 



Loew observed in the Berlin Botanic Garden a hover-fly, Syrphus balteatus 

 Deg., po-dvg.; Alfken at Bremen 3 po-cltg. Apidae, Bombus lucorum Z. g, 

 Andrena nitida Fourc. 5, and A. nigro-aenea K. 2, the last two flvinsr laboriously 

 with disarranged wings, and carrying very heavy loads of pollen, destined to store 

 cells in the case of the last-named species ; Hoffer records from Steiermark, Bombus 

 agrorum F. 2. carrying huge loads of pollen, and Bombus terrester Z. $ freq.; 

 MacLeod noted in Flanders, Apis, 3 humble-bees, 2 species of Halictus, 5 hover- 

 flies, and a Muscid (B. Jaarb. Dodonaea, Ghent, vi, 1894, pp. 186-7). 



42. Eschscholtzia Cham. 



Homogamous pollen flowers, usually yellow in colour. 



144. E. californica Cham. (F. Miiller, Bot. Ztg., Leipzig, xxvi, 1868 ; Dai win, 

 op. cit., xxvii, 1869 ; Hildebrand, Jahrb.wiss. Bot., Leipzig, vii, 1869-70; Herm. Miiller, 

 ' Fertilisation,' pp. 94-5, ' Weit. Beob./ I, p. 323 ; Knuth, ' Blutenbiol. Herbstbeob.') 

 The filiform stigmas are at first closely surrounded by the crowded stamens, but 



DAVIS. II -a 



