. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 68 ANGIOSPERMAE—DICOTYLEDONES at the only two places where there are openings into the interior of the flower. The parts of the filaments projecting from the flower—together with the anthers—he close together, surrounding the stiff style with its stigma, and they themselves are covered with a hood formed by the fusion of the tips of the two inner petals. Some considerable time before the flower opens the anthers dehisce, discharging their pollen upon the lar
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. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 68 ANGIOSPERMAE—DICOTYLEDONES at the only two places where there are openings into the interior of the flower. The parts of the filaments projecting from the flower—together with the anthers—he close together, surrounding the stiff style with its stigma, and they themselves are covered with a hood formed by the fusion of the tips of the two inner petals. Some considerable time before the flower opens the anthers dehisce, discharging their pollen upon the large lobed stigma—which is already mature—and there the pollen lies surrounded by the hood. Automatic self-pollination would therefore be inevitable, and the pollen could never escape from its close envelope, were not crossing effected by insects, which in this case are exclusively bees. When a bee hangs on to the flower to suck nectar, it must push aside the hood and the flexible stamens this encloses with the under-side of its body, and—with the hairs on its ventral surface—sweep off the pollen from- the stigma, which owing to the rigidity of the style is not deflected. As soon as the bee leaves, the hood returns to its former position, and again ensheaths the anthers and stigma. There being two 12 3 4. Fig. 23. /J/i:/v/r« .s/'«i'a«/7«, ifSC. (after Hlldebrand). (1) Flower, natural size. (2) The same after removal of half an outer petal : the hood is pressed aside : the dotted line beffinning at e, indicates the path of the insect's probo=icis. {3) The sexual organs of a bud. (4) The pistil and the two middle stamens of a bud before dehiscence of the anthers. nectaries, these events happen twice during a visit to each blossom. In younger flowers therefore the pollen on the stigma is removed by the bee, and carried to the stigma of an older flower, which has already been robbed of its own pollen. Visitors.—Since the curved channels of Diclytra spectabilis are