File:Flying seeds 2.jpg

Identifier: naturalhistoryof02kern 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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Text Appearing Before Image: Fig. 467—Dispersion of fruits and seeds by tin ^^ZITlSiTr ;^^««.^»^«-; Polygonum SieboMi. ^ PteUa tri/oliala. * J..chynon^^ glnbrata^Opoponax Cretica 7 Banuterta Smemarumxs. > Oyrocarpus Asiatiats. » TriopUHs bsfurca. lo aJMo,,svJulauum,^^ Artedia SQuamata. ^^ Betula verrucosa, is r«,*rn.-/.„«./«*.v„;. f v ^tc Muiitpe*tuuinum, ■ squamata. 12 Betula verrucosa, is Laserpitium lati/oUiii. Oriental Hornbeam {Garpinus Orientalis), and the Lime {Tilia intei-niedia) (set figs. 4681 and 468 2). In many cases, as, for instance, in tlio Tree of H.^aven [A ilun- 854 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. thus), the two wings exhibit a slight spiral twist resembling a propeller; thisoccasions a peculiar gyratory motion of the fruit as it sails along in the air.Wherever there is only a single wing which projects from one side, the centre ofgravity has an eccentric position, and the fruits and seeds of this class spin quickly

Text Appearing After Image: Fig. 468.—Dispersion of fruits and setils hy tlit- wiiul. Carpinus Orienlalk. 2 Tilia intermedia. « Armeria alpina. < Melica altissima. * Dryohalanops. 6 Paronychia Kapclla. Briza maxima. 8 Scabiosa graminifolia. ^ Humulus Liipvlus. i Tri/olium nidificum. as they fall freely through the air. The motion in question is particularly wellmarked in the half-fruits of the Sycamore and the seeds of Pines. The same object as is attained in the above cases by the development of alateprocesses is brought about in other plants by the transformation of dry bracts orfloral-leaves into light, loose, saccate, or inflated envelopes round the fruits or seeds. DISPERSAL BY WIND, 855 When quite dry, these envelopes are extremely thin and delicate, and sometimestheir weight is still further reduced by a portion of the tissue being torn duringdesiccation, in which case the whole assumes a sieve-like or latticed appearance.The small fruit within the envelope defines the position of the centre of grav

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