BORAGINEAE 127 



lube, and the stamens half-way down. The pollen-grains of the short-styled flowers 

 are larger than those of the long-styled ones. 



Nectar-sucking bees or Lepidoptera touch the anthers or stigma in the entrance 

 of the flower with their heads or the base of their proboscis, while the middle of the 

 latter comes into contact with the reproductive organs placed half-way down the 

 corolla-tube. Legitimate crossing is thus effected. Smaller insects which creep into 

 the flowers bring about either legitimate or illegitimate union. Owing to the large 

 amount of nectar in the flowers, their conspicuousness, and the fact that they flower 

 very early in the year, when there are but few other competing species, insect-visits 

 are very numerous. In correlation with this we find that the flowers are unable to 

 automatically pollinate themselves (though Kerner says that the long-styled form may 

 do so), and illegitimate union is inefl"ective. The experiments on artificial pollination 

 carried out by Hildebrand have demonstrated that when flowers are fertilized by 

 means of their own pollen, or that from others of the same kind, no fruits are set, 

 while legitimate union is followed by about the same amount of fertility as in nature. 

 It has further been shown by the researches of Cobelli (Nuovo Giorn. bot. ital., 

 Firenze, xxv, 1893) '^^' "o fruits are set when visitors are excluded. In wild plants 

 investigated by Hildebrand the first flowers were often infertile, and this was almost 

 always the case with the terminal one on each branch. He suggests that the first 

 fact can be explained on the assumption that there are no visitors when the plant 

 begins to flower ; while as to the second he suggests that the supply of nutriment 

 passing up the branches is not sufficient to reach their tips, but is appropriated by the 

 fruits developing below. 



Schulz observed protandry as well as homogamy. 



Visitors. — Herm. Miiller gives the following list for Westphalia (W.) and 

 Thuringia (T.). — 



A. Coleoptera. Slaphylinidae : i. Omalium florale Payk., freq., creeping 

 about in the flowers (W.). B. Diptera. (a) Bombyliidae: 2. Bombylius discolor 

 Mg., freq., but only during warm sunshine, casually skg. (W.) ; 3. B. major L., do. 

 (W.). (b) Syrphidae: 4. RhingiarostrataZ., very common, skg. (W.). C. Hymeno- 

 ptera. Apidae: 5. Andrena gwynana A". 5, po-cltg. (T.); 6. Anthophora pilipes 

 F. 2 and 5, numerous, skg. and po-cltg. (W., T.); 7. Bombus agrorum F. j, freq., 

 skg. (W.); 8. B. hortorum L. 5, very common (W.) ; 9. B. lapidarius L. 5, skg. (W.) ; 

 10. B. pratorum L. 5, skg. (W., T.) ; 11. B. rajellus K. j, skg. (W., T.) ; 12. B. 

 muscorum F. j, skg. (W.); 13. B. sylvarum L. 5, freq., skg. (W., T.); 14. B. ter- 

 rester Z. 5, skg. (W., T.) ; 15. Halictus cylindricus F. 5, po-cltg. (W.); 16. Osmia 

 fusca Chr., J and S, freq., skg. and po-cltg. (W.) ; 17. O. pilicornis Sm. t and 5, skg. 

 and po-cltg. (W.) ; 18. O. rufa Z. 5, skg. (W.). D. Lepidoptera. Rhopalocera : 

 19. Rhodocera rhamni Z., freq., skg. (W.). 



The following were recorded by the observers, and for the localities stated. — 



Knuth, 5 bees, all skg. legitimately — 1. Apis mellifica Z. 5 (2.5. '96, very 

 numerous); 2. Anthophora pilipes i'^. 5 and t> (25. 4. '95); 3. Bombus agrorum F. 

 5 (28. 4. '96); 4. B. hortorum Z. ? (25. 4. '95); 5. B. lapidarius Z. % (28. 4. '96). 

 Bail (West Prussia), the butterfly Anthocharis cardamines Z. (Bot. Centralb., Cassel, 

 ix, 1882). Loew (Brandenberg), 3 bees (' Beitrage,' p. 46) — i. Anthophora pilipes 

 F. S, skg.; 2. Bombus agrorum/". 5, do.; 3. B. lapidarius Z. j, do., one 5 visited loo 

 flowers in about 4 minutes ; (Berlin Botanic Garden), the bee Andrena nitida Fourcr. 

 S, po-cltg. and, on a variety, 3 bees — i. Bombus agrorum F.<^; 2. B. hortorum Z. 



