. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 254 ANGIOSPERMAE—DICOTYLEDONES fact that the iirst flowers of an inflorescence to open are all purely male (with vestigial pistils), while it usually happens that in the lower part of the inflorescence, some flowers are actually female, since their anthers fall oflF without dehiscing, although the pollen-sacs are full of pollen-grains (Miiller). Martelli states (op. cit.) that the lowest flowers are the only fertile ones, and that not more than two to four o
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 254 ANGIOSPERMAE—DICOTYLEDONES fact that the iirst flowers of an inflorescence to open are all purely male (with vestigial pistils), while it usually happens that in the lower part of the inflorescence, some flowers are actually female, since their anthers fall oflF without dehiscing, although the pollen-sacs are full of pollen-grains (Miiller). Martelli states (op. cit.) that the lowest flowers are the only fertile ones, and that not more than two to four of them produce seeds, these being the fourth (rarely the third) to the seventh in regular succession, counting from the base of the cyme. Warnstorf (Schr. natw. Ver., Wernigerode, xi, 1896, pp. 1-12) gives a similar account of the distribution of the sexes. The lower flowers of the panicle are male, and are the first to open; towards the middle isolated pseudo-hermaphrodite pollen- flowers, with no style and a sessile stigma are often to be found. The upper flowers are hermaphrodite and protogynous, with projecting styles; their ovaries are beset with stalked red glands of large size. The smooth pollen-grains are vermilion in colour and ellipsoidal, with several longitudinal furrows ; size about 20 /«, broad and 37-40 /i, long. The dimensions of the flowers correspond with those of the chief visitors, humble-bees, which when alighting at once settle in the most convenient position. Fig. 78. Aesculus Hippocastanum^ L. (After Herm. Miiller.) i. Male flower in section. 2, Herm- aphrodite flower in the first (male) condition, seen obliquely from the front. 3. The same in the second (female) condition, in section, a, anthers; «, nectary; (Jz/, ovary ; oz'', vestigial ovary; ^.petals; j, sepals; St. stigma. for sucking, and in so doing touch either the stigma or the anthers with the under- side of the abdomen, so that cross-pollination is always effected. The other bees observed
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