. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. BORAGINEAE 137. I'~IG. 276- Litliospeymum arvense, L. (after Herm. Muller). (I) End of the style, taken from a bud (x 36). St, stigma. (2) Position of the reproductive organs in the flower. of the anthers, so that the entrance of the flower is completely filled, and the proboscis of an insect probing for nectar must force its way between anthers and stigma. If this takes place at the beginning of anthesis, and the proboscis has previously been dusted with po
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. BORAGINEAE 137. I'~IG. 276- Litliospeymum arvense, L. (after Herm. Muller). (I) End of the style, taken from a bud (x 36). St, stigma. (2) Position of the reproductive organs in the flower. of the anthers, so that the entrance of the flower is completely filled, and the proboscis of an insect probing for nectar must force its way between anthers and stigma. If this takes place at the beginning of anthesis, and the proboscis has previously been dusted with pollen, crossing will be effected, and a fresh supply of pollen will adhere to the organ. Soon, however, the anthers dehisce so strongly that the stigma gets covered with pollen, so that autogamy is inevitable. Insect-visits are but few. Visitors.—The following were recorded by the observers, and for the localities stated.— Knuth, 2 bees (Apis mellifica L. 5, and Bombus lapidarius L. 5), skg., and a butter- fly (Pieris brassicae Z.). Sprengel also observed the ' common white butterfly.' Herm. Muller.—A. Diptera. Syrphidae: I. Rhingia rostrata L.; 2. Syritta pipiens L. B. Hymenoptera. Apidae: 3. Apis mel- lifica Z. 5, skg. ; 4. Bombus agrorum Z. J, do. C. Lepidoptera, Rhopalocera: all skg. : 5. Pieris brassicae Z.; 6. P. napi Z.; 7. P. rapae Z. MacLeod (Flanders), a Lepidopterid (Hot. Jaarb. Dodonaea, Ghent, vi, 1894, p. 371). 1996. L. canescens Lehm.—Darwin describes the flowers of this species as either heterostylous or very variable in regard to the length of the style. 1997. L. purpurocaeruleum L. (Kirchner, ' Beitrage,' p. 51; Loew, ' Bliitenbiol. Floristik,' p. 282.)—The tolerably large flowers of this species exhibit a similar colour change to that of Pulmonaria, being first purple-red and afterwards blue. Kirchner found the plant to be feebly protogyncus in the Swabian Alps, the stigma being mature when the flowers opened, and the anthers dehiscing shortly afterw
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