Text-book of botany : morphological and physiological / by Julius Sachs ; translated and annotated by Alfred W. Bennett ; assisted by W.T. Thiselton Dyer.

Date:: 1875

Credit: Text-book of botany : morphological and physiological / by Julius Sachs ; translated and annotated by Alfred W. Bennett ; assisted by W.T. Thiselton Dyer. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

828/880 (page 812)

$become attached to its hairs, feet, or proboscis, and afterwards, when assuming similar positions, to be applied to the stigmas of other flowers. In dichogamous plants the movements of the stamens, styles, or arms of the stigmas assist this end, taking place frequently in such a way that at one time the open anthers occupy the same position in the flower that the receptive stigmas do at another time, so that the insect, when taking up the same position, touches the open anthers in one flower and the receptive stigmas in another flower with the same part of its body. The same result is also ob- tained in dimorphic flowers, the pollination being in these cases efficacious when anthers FIG. 457.—Aristolochia Clematitis: a piece of a stem st with petiole b; in the axil of this are flowers of different ages; 1, 1 young flowers not yet fertilised ; 2, 2 fertilised flowers, the pedicels bent downwards; k swollen part of the tube of the perianth r; /the inferior ovary (natural size). FIG. 458.—Aristolochia Clematitis: the perianth cut through longitudinally. A before, B after pollination (magnified). and stigmas which occupy the same position in different flowers are made mutually to act on one another. But there are besides many other contrivances, most variable in their nature and often perfectly astonishing, for effecting the conveyance of pollen by insects. A few examples may suffice. (1) Dichogamous Flowers1 are either protandrous or protogynous2. In the former the stamens are developed first, their anthers opening at a time when the stigmas are still undeveloped and not yet receptive; the stigmatic surface is only developed later, and 1 F. Delpino, Ulteriori osse'rvazioni sulla dicogamia nel regno vegetabili, Atti della soc. Ital. di sci. nat. vol. XIII, 1869, and Bot. Zeit. 1871, No. 26 et seq.\ ditto, in Bot. Zeit. 1869, p. 792. 2 [For a list of British protandrous, protogynous, and ‘synacmic’ plants (or those in which the male and female organs are mature at nearly the same time), see A. W. Bennett in Journal of Botany, 1870, p. 315, and 1873, p. 329.—Ed.]$