. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. no ANGIOSPERMAE—DICOTYLEDONES 265. D. aurea M. Vahl.—Warming says that this species differs from the pre- ceding in having the nectar more deeply concealed. The long claws of the petals are closely apposed to form a tube, so that only insects with a long proboscis can reach the nectar. In the homogamous flowers automatic self-pollination can only be effected by the long stamens, while the short ones serve for cross-pollination. 266. D. alpina L.—Lindman says
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. no ANGIOSPERMAE—DICOTYLEDONES 265. D. aurea M. Vahl.—Warming says that this species differs from the pre- ceding in having the nectar more deeply concealed. The long claws of the petals are closely apposed to form a tube, so that only insects with a long proboscis can reach the nectar. In the homogamous flowers automatic self-pollination can only be effected by the long stamens, while the short ones serve for cross-pollination. 266. D. alpina L.—Lindman says that this species is homogamous—on the Dovrefjeld—and capable of automatic self-pollination. According to Ekstam, the protogynous-homogamous flowers in Nova Zemlia agree in structure with those of Scandinavia and Greenland. The same botanist has observed plants in Spitzbergen bearing flowers and fruits during the height of summer ('Bliitenbiol. Beob. a. Spitzbergen,' p. 20). The flowers were homogamous, 5-7 mm. in diameter, faintly fragrant, and with yellow petals. Visitors.—In Spitzbergen, Ekstam observed that the flowers were visited by a number of small Diptera. 267. D. crassifolia L.—Warming says that this species is homogamous and autogamous in the Arctic regions. 79. Kernera Med. Small white homogamous flowers, with half-concealed nectar. Four nectaries. 268. K. saxatilis Reichb. (=Cochlearia saxatilis Lam.). (Herm. Miiller, ' Alpenblumen,' p. 147.)—The flowers are homogamous. There is a green fleshy nodule secreting nectar on either side the base of each short stamen. The petals are at first small and erect, but subsequendy expand. The anthers of the four long stamens are close to those of the two short ones: all six dehisce introrsely, and are so placed that an insect sucking nectar must touch them with one side, and the stigma with the other side, thus favouring cross-pollination. In dull weather the flowers remain half closed, when automatic self-poll
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