. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. SCROPHULARINEAE 183 humble-bee Bombus hortorum L. 5 and 5. The first two add that Bombus terrester L. 5 perforates the flowers and steals the nectar. 2103. D. ambigua Murr. ( = D. oc\\ro\t\xcs. Jacq., and D. grandiflora Lam.). (Herm. Muller, ' Alpenblumen,' p. 275, ' Weit. Beob.,' Ill, pp. 30-1; Kirchner, 'Flora V. Stuttgart,' pp. 585-6; Ludwig, Kosmos, Stuttgart, xvii, 1885; Schulz, 'Beitrage'; Loew, ' Bliitenbiol. Floristik,' p. 395.)—The flower mechanism
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. SCROPHULARINEAE 183 humble-bee Bombus hortorum L. 5 and 5. The first two add that Bombus terrester L. 5 perforates the flowers and steals the nectar. 2103. D. ambigua Murr. ( = D. oc\\ro\t\xcs. Jacq., and D. grandiflora Lam.). (Herm. Muller, ' Alpenblumen,' p. 275, ' Weit. Beob.,' Ill, pp. 30-1; Kirchner, 'Flora V. Stuttgart,' pp. 585-6; Ludwig, Kosmos, Stuttgart, xvii, 1885; Schulz, 'Beitrage'; Loew, ' Bliitenbiol. Floristik,' p. 395.)—The flower mechanism of this species resembles that of D. purpurea. The corolla is dull yellow in colour, and a network of brown lines on the inner surface of the lower lip serves as a nectar- guide. The flower is so broad that humble-bees of any size can conveniently creep into it and suck the nectar. Its entrance is 20-22 mm. broad and 12 mm. high, so that even the smaller bees touch the anthers and stigma, and as protandry is marked cross-pollination is ensured. The same end is further attained by the fact that humble-bees are in the habit of working up the inflorescences from Fig. 292. Digitalis luiea, L. (after Herm. Mailer). A. Flower in the first (male) stage, seen from the side. B. Do., seen directly from the front. C. Do., after removal of most of the corolla, seen from below. D. Pistil of do., seen from the side. E. Reproductive organs, during the dehiscence of the anthersof the long stamens. F. Do., during the dehiscence of the anthers of the short stamens; the two short papillose stigmatic lobes are expanded (x 3i). a, anthers of the long stamens ; w, nectary. Should insect-visits fail, automatic self-pollination may possibly be effected by pollen still clinging to the anthers. Besides hermaphrodite plants, Ludwig also observed small-flowered female stocks with reduced vegetative organs, there being 2 % of these at Greiz and Plauen. Visitors.—The following were recorded by t
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