. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. GEITONOGAMY 41 III. Geitonogamy. Kerner, in his paper ' Die Schutzmittel der Bliite,' was the first to distinguish between Geitonogamy and Xenogamy. According to the few experiments of Darwin (' The Effects of Cross- and Self-fertilisation') and of Hildebrand (' Geschlechter- verteilung,' pp. 67, 68) it appears, as was to be expected, to be less advantageous for the plant than Xenogamy, but considerably more advantageous than Autogamy. Geitonogamy is brought
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. GEITONOGAMY 41 III. Geitonogamy. Kerner, in his paper ' Die Schutzmittel der Bliite,' was the first to distinguish between Geitonogamy and Xenogamy. According to the few experiments of Darwin (' The Effects of Cross- and Self-fertilisation') and of Hildebrand (' Geschlechter- verteilung,' pp. 67, 68) it appears, as was to be expected, to be less advantageous for the plant than Xenogamy, but considerably more advantageous than Autogamy. Geitonogamy is brought about not only by atmospheric currents and the agency of insects, but also by mature stigmas coming into contact with the pollen-covered anthers of neighbouring flowers, or by the fall of pollen. Kerner gives a full account of these two latter kinds of Geitonogamy in his ' Nat. Hist. PI.' (Eng. Ed. i, II, pp. 318-31). According to this investigator the significance of crowded inflorescences (Com- positae, Umbelliferae, &c.), lies chiefly in the crossing that results between neigh-. FlG, 2. Geiiono^amywith adhesive pollen {\.er K^Tj\<tY). (i) Crossing; of branches of the styles of adjacent florets in the capitulum of Eupatorium cannabinum. (2) Longitudinal section through the upper parts of a young floret of Eupatorium : the two branches of the style lie parallel to one another, enclosed in the anther-cylinder, which is again surrounded by the corolla-tube, (3) Umbellule of Chaero- phyllum aromaticum : the true hermaphrodite florets are open, the pseudo-hermaphrodite pollen-florets still closed. (4) The same umbellule : the true hermaphrodite florets are now without stamens, the pseudo- hermaphrodite florets are open, pollen is dropping from the anthers of the latter upon the stigmas of the former. bouring flowers of the same plant. In numerous Compositae belonging to the group Liguliflorae, the spreading branches of the stigmas of adjacent florets intertwine at the e
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