. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 3IO ANGIOSPERMAE—DICOTYLEDONES Cross-pollination is thus effected by insect-visits. (Hermann Miiller did not observe automatic self-pollination; Axell, however, says that it does occur and is effective.) In addition to hermaphrodite flowers, there are often female ones, according to Schulz, up to 50%, generally 10-20%, and these are distributed partly gynomonoe- ciously and partly gynodioeciously. Kirchner describes two forms of small-flowered female stocks.


. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 3IO ANGIOSPERMAE—DICOTYLEDONES Cross-pollination is thus effected by insect-visits. (Hermann Miiller did not observe automatic self-pollination; Axell, however, says that it does occur and is effective.) In addition to hermaphrodite flowers, there are often female ones, according to Schulz, up to 50%, generally 10-20%, and these are distributed partly gynomonoe- ciously and partly gynodioeciously. Kirchner describes two forms of small-flowered female stocks. In one case the corolla is of the normal form; the stamens in the usual position, but with white indehiscent anthers, and the style of the same length as the upper lip. The other kind of female flower possesses stamens still further reduced; the lower lip is directed so far upwards that the entrance of the corolla is only one mm. high; and the stigma projects far beyond the upper lip. Besides large hermaphrodite flowers, MacLeod observed smaller ones (at Ghent), which seemed to be almost cleistogamous and were self-fertilized. There were many intermediate stages between the two types. Purely female flowers were not observed. Warnstorf describes three forms for Neu- Ruppin.— (i) Large flowers : corolla 15-16 mm. long from the base of the tube to the tip of the upper lip, entrance wide; corolla-tube longer than the calyx ; lower lip strongly and irregularly dentate ; hermaphrodite; style generally of the same length as the longer stamens; autogamy effected by the rolling up of the stigmatic branches ; pollen-grains white in colour, ellipsoidal, tuberculate, about 50-56 It long and 37-43 /^ broad. (2) Medium-sized flowers : corolla 10-12 mm. long, entrance wide; style sometimes of the same length as the longer stamens, sometimes a little shorter; sometimes hermaphrodite, with anthers partly reduced or entirely aborted. (3) Small flowers: corolla only 8 mm. long; lower lip cur


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