190 ANGIOSPERMAE—DICOTYLEDONES 



Warnstorf, Verb. bot. Ver., Berlin, xxxviii, 1896.) — Hermann MuUer states that some 

 of the ten stamens are almost always vestigial, these being usually the inner five, and 

 often one or two of the outer whorl in addition. The nectaries are situated on the 

 bases of the five outer stamens, and secrete during sunny weather. The anthers 

 dehisce successively, either simultaneously with the maturation of the stigmas, or 

 somewhat earlier, or rather later. According to Kerner, autogamy takes place when 

 the flowers begin to close. Warnstorf says that at Ruppin the plant bears either 

 hermaphrodite flowers or pseudo-hermaphrodite fruiting flowers. The former possess 

 two to five, or more rarely six to eight stamens, which have violet anthers projecting 

 beyond the stigmas or at the same level, and eff'ect autogamy by moving inwards. 

 In the pseudo-hermaphrodite fruiting flowers all or some of the stamens have 

 degenerated. The variety decandra is markedly protandrous. Automatic self-pollina- 

 tion takes place when the flowers close, and results in autocarpy. According to 

 Anna Bateson, plants produced by crossing are somewhat larger and heavier than 

 those resulting from autocarpy in the proportion of 100: 91; Celakovsky states that 

 the variety boraeana is cleistogamous. 



In Greenland, according to Warming, the hermaphrodite flowers agree in their 

 mechanism with those of Europe, and there are also female ones, distributed 

 gynodioeciously or gynomonoeciously. Cleistogamy obtains in the same country. 



Plants observed by Vanhoffen in Greenland (Abromeit, ' Bot. Ergeb. v. Dry- 

 galski's Gronlandsexped.,' p. 20), and by Andersson and Hesselman in Spitzbergen 

 ('Bidrag till Kanned. om Spetsbergens o. Beeren Eil. Karlvaxtflora,' p. 86), were 

 sterile, like several other introduced weeds. 



This species flowers so early that it has few rivals, and occurs in such numbers 

 that visitors are moderately numerous in spite of the smallness of its flowers. In 

 the hermaphrodite blossoms these may effect either cross- or self-pollination. 



Visitors. — Hermann Miiller (H. M.) in Westphalia and myself (Kn.) in Schles- 

 wig-Holstein have observed the following. — 



A. Diptera. {a) Miiscidae : 1. Anthomyia sp., skg. (H. M.) ; 2. Chlorops cir- 

 cumdata Mg., industriously skg. (H. M.) ; 3. Lucilia cornicina F., po-dvg. (Kn.) ; 

 4. Musca corvina F., ditto (H. M.); 5. M. domestica Z., ditto (H. M., Kn.) ; 6. 

 Pollenia rudis F., po-dvg. (Kn.); 7. Scatophaga sp., po-dvg. (Kn.) ; 8. Sepsis sp., 

 skg. (H.M.). {b) Syrphidae: 9. Ascia podagrica F., skg. (H. M.); 10. Cheilosia 

 sp., skg. (H. M.) ; II. Eristalis arbustorum, L., po-dvg. (Kn.); 12. Syritta pipiens 

 L., skg. and po-dvg. (H. M., Kn.); 13. Syrphus corollae F., po-dvg. (Kn.); 14. S. 

 ribesii L., po-dvg. (Kn.). B. Hymenoptera. (a) Apidae: 15. Andrena albicans 

 Mull. ?, skg. (H. M) ; 16. A. albicrus K. t, skg. (H. M.) ; 17. A. chrysosceles K. S, 

 skg. (H. M.); 18. A. dorsata K. 5, skg. (H. M.); 19. A. fasciata Wesm. t, skg. 

 (H. M.) ; 20. A. florea 5 and S, skg. (H. M.) ; 21. A. fulvicrus K. S, skg. (H. M.) ; 

 22. A. gwynana K. 5, skg. and po-cltg. (H. M.) ; 23. A. smithella K. S, skg. (H. M.) ; 

 24. Apis mellifica L. 5, skg. (Kn.) ; 25. Halictus cylindricus F., skg. (Kn.) ; 26. 

 H. flavipes F. $, skg. (H.M., Kn.); 27. H. leucopus K. $, skg. (H. M.); 28. H. 

 sexstrigatus Schenck 5, skg. (H. M.); 29. Osmia rufa Z. i, skg. (H. M.); 30. 

 Sphecodes gibbus Z. 5, skg. (H. M.). (b) Cynipidae: 31. Eucoela sp. (H. M.). 

 C. Thysanoptera. 32. Thrips, po-dvg. (H. M.). 



MacLeod noticed Apis, 14 other short-tongued Hymenoptera, 7 Syrphidae, 

 10 other Diptera, and 2 beetles in Flanders (Bot. Jaarb. Dodonaea, Ghent, vi, 1894, 

 pp. 166-7). 



