. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. SCROPHULARINEAE i8i aioi. D. purpurea L. (Sprengel, ' Entd. Geh.,' p. 325 ; Ogle, Pop. Sci. Rev., London, ix, 1870, p. 49 ; Herm. MuUer,' Fertilisation,' pp. 437-8 ; Ludwig, Kosmos, Stuttgart, xvii, 1885, p. 107; Kirchner, -Flora v. Stuttgart,' p. 585; Knuth, ' Blutenbiol. Beob. in Thuringen,' ' Bliitenbesucher,' II, ' Bliitenbiol. Beob. a. d. Ins. Riigen'; ' Bloemenbiol. Bijdragen.')—The large red flowers of this species are aggregated into very conspicuous
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. SCROPHULARINEAE i8i aioi. D. purpurea L. (Sprengel, ' Entd. Geh.,' p. 325 ; Ogle, Pop. Sci. Rev., London, ix, 1870, p. 49 ; Herm. MuUer,' Fertilisation,' pp. 437-8 ; Ludwig, Kosmos, Stuttgart, xvii, 1885, p. 107; Kirchner, -Flora v. Stuttgart,' p. 585; Knuth, ' Blutenbiol. Beob. in Thuringen,' ' Bliitenbesucher,' II, ' Bliitenbiol. Beob. a. d. Ins. Riigen'; ' Bloemenbiol. Bijdragen.')—The large red flowers of this species are aggregated into very conspicuous unilateral racemes. Their form is that of an elongated, somewhat flattened cylinder, obliquely truncated, and slanting down- wards: 4^-5| cm. long and i-5-i-7 cm. broad. {Cf. Fig. 290.) The position and form of the corolla protect the internal parts of the flower from rain. The inner side of the corolla on its somewhat produced lower lip is provided with nectar-guides in the form of dark-purple blotches with white margins. This region is beset with hairs 5 mm. long, which serve, according to Kirchner, to prevent the smaller useless insects from getting at the nectar. It seems to me, however, that they are so loosely arranged and so limited in extent, that they are not able to prevent such insects from creeping into the flowers. My opinion is that these hairs give insect-visitors a firm grip- Nectar is secreted by an annular swell- ing below the ovary, and stored in the base of the corolla-tube. The dimensions of the bell correspond to those of humble-bees, and as a matter of fact it is these insects only which seek out the nectar of the fox- glove and effect pollination in doing so. The style and stamens lie against the upper side of the corolla on the way to the nectar, so that a humble-bee creeping right into the flower and probing for nectar must F"=- ^90- DigUcUspurpurea, l. (after Plateau). ^ Flower, natural size. touch the anthers and stigma with its dor- sal surf
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