. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 248 ANGIOSPERMAE—DICOTYLEDONES situated beneath the ovary secretes abundant nectar, which is concealed in the base of the corolla-tube; in hermaphrodite flowers this is about 3 mm., and in female ones about 2 mm. long. The mouth of the flower is fully lA mm. and one mm. in diameter respectively. The nectar is therefore accessible even to short-tongued insects. It is protected from rain by hairs reaching from the inner surface of the corolla-tube to its middl
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. 248 ANGIOSPERMAE—DICOTYLEDONES situated beneath the ovary secretes abundant nectar, which is concealed in the base of the corolla-tube; in hermaphrodite flowers this is about 3 mm., and in female ones about 2 mm. long. The mouth of the flower is fully lA mm. and one mm. in diameter respectively. The nectar is therefore accessible even to short-tongued insects. It is protected from rain by hairs reaching from the inner surface of the corolla-tube to its middle. Hermann Miilier states from actual observation that the large, and therefore more conspicuous, hermaphrodite stocks are first visited by insects, and the smaller, less conspicuous female ones afterwards. Gynomonoecious stocks may be rare, or sporadically may be the only ones present. Hermaphrodite and female ones are about equally numerous. Mowes also found the species to be gynodioecious, with large-flowered hermaphrodite and small-flowered female Fig. 326. Mentha, L. (after Herm. Miilier). (1-4) Mentha arvensts, L. (i) Female flower. (3) Hermaphrodite do., in the first (male) stage. (3) Do., in the second (female) stage. (4) Ovary {ov) and nectary (w). (5) Mentha aguatica, L. Female flower seen obliquely from the front, to show the vestigial stamens, foreshortened. a\ vestigial stamens. (I) and (5) should be supposed twisted round to the right into a horizontal position. Schulz says that the species is gynomonoecious and gynodioecious, and that occasionally 50 % or more of the stocks are female. In other stations purely gynomonoecious plants are to be found. He adds that the female flowers are visited by insects quite as frequently as the hermaphrodite ones. Warnstorf observed both gynomoecism and gynodioecism at Ruppin. Visitors.—Knuth observed the following.— A. Diptera. (a) Muscidae: i. Lucilia caesar Z., skg. (h) Syrphidae: 2. Syritta pipiens Z., skg. an
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