File:The natural history of plants, their forms, growth, reproduction, and distribution; (1902) (14579131717).jpg

Identifier: naturalhistoryof02kern (find matches)
Title: The natural history of plants, their forms, growth, reproduction, and distribution;
Year: 1902 (1900s)
Authors: Kerner von Marilaun, Anton, 1831-1898 Oliver, Francis Wall, 1864- Macdonald, Mary Frances Ewart Busk, Marian Balfour, Lady
Subjects: Botany
Publisher: London, Blackie
Contributing Library: NCSU Libraries
Digitizing Sponsor: NCSU Libraries

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nollen from atmospheric deposits. When the needful wind arises it blows theollen out through the chinks in the bladder and conveys it to the stigmas offcher plants of the same species. Plants of the Globe-flower (TroUius) genus, whose species grow in the Arcticigions in damp situations and also further south in mountainous districts of tl.e 110 PROTECTION OF POLLEN. Old World, are daily exposed to rain or heavy dew. Nevertheless their pollenis never wetted, the anthers being completely shut in by the perianth-leaves,which are spirally inserted on the receptacle and closely furled one upon another.These flowers have a ring of stalked nectaries round the stamens, and insectswhich visit them for the sake of the honey are obliged to break through the roofformed by the overlapping perianth-leaves in order to reach the inside of theflower. The pliability of these leaves enables bees by their weight to effect anentrance, whilst falling drops of rain cannot penetrate, but roll off the flower.
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Fig. 221.—Protection of Pollen from Wet. « Ariopsis peltata. 2 Flower of Trolling europmus. « The same with some of the floral-leaves removed. ♦ Digitalis luUscens.6 A single flower of Digitalis hUescem in longitudinal section. « Aretia glacialis. Single flower of Aretia glacialis inlongitudinal section (magnified). Also in Corydalis, Calceolarias, Toad-Flax and Snap-dragon (Corydalis, Calceolaria,Linaria, Antirrhinum) the corolla forms a closed envelope round the anthers;and again in papilionaceous flowers the pollen is, up to the moment of an insectsvisit, hidden in the cavity formed by the two petals of the keel.\y The majority of lipped flowers—Butterwort, Yellow-rattle, Cow-wheat, andEye-bright (Pinguicula, Rhinanthus, Melampyrum, Euphrasia, cf. fig. 220^)—as also the Violet (Viola), Monkshood (Aconitum), and innumerable other plantswhose flowers open laterally, do not regularly inclose the pollen, but protect itagainst rain or dew by means of an arched portion of the

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