The different forms of flowers on plants of the same species / by Charles Darwin.

  • Darwin Charles, 1809-1882.
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: The different forms of flowers on plants of the same species / by Charles Darwin. 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.

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    me that he could detect no difference in the size of the pollen- grains in the two forms. Nevertheless, there can be no doubt that this plant is heterostyled. Lipostoma [sp. ?] (Rubiaoe^). Dried flowers of this plant, which grows in small wet ditches in St. Catharina, in Brazil, were likewise sent me by Fritz Muller. In the long-styled form the exserted stigma stands rather above the level of the exserted anthers of the other form; whilst in the short-styled form it stands on a level with the anthers of the other form. So that the want of strict corre- spondence in height between the stigmas and anthers in the two forms is reversed, compared with what occurs in Hedyotis. The long-styled pistil is to that of the short-styled as 100 to 36 in length; and its divergent stigmas are longer by fully one-third of their own length than those of the short-styled form. In the latter the anthers are a little larger, and the pollen-grains are as 100 to 80 in diameter, compared with those from the long- styled form. Cinchona miceantha (Eubiace.®). Dried specimens of both forms of this plant were sent me from Kew.* In the long-styled form the apex of the stigma stands just beneath the bases of the hairy lobes of the corolla; whilst the summits of the anthers are seated about halfway down the tube. The pistil is in length as 100 to 38 to that of the short-styled form. In the latter the anthers occupy the same position as the stigma of the other form, and they are con- siderably longer than those of the long-styled form. As the summit of the stigma in the short-styled form stands beneath the bases of the anthers, which are seated halfway down the corolla, the style has been extremely shortened in this form; its length to that of the long-styled being, in the specimens examined, only as 5 • 3 to 100! The stigma, also, in the short- styled form is very much shorter than that in the long-styled, in the ratio of 57 to 100. The pollen-grains from the short- * My attention was called to 3, given by Mr. Markham in his this ])lant by a drawing copied ‘ Travels in Peru,’ p. 539. from Howard’s ‘ Quinologia,’ Tab.