Structural botany by Gray Asa 1810-1888

Author:Gray, Asa, 1810-1888. [from old catalog]
Language: eng
Format: epub
Tags: Plant anatomy
Publisher: New York and Chicago, Ivison, Blakeman, Taylor, and company
Published: 1879-03-25T05:00:00+00:00

Short-styled.

false coadaptation." The whole arrangement is displayed in tl)e annexed diagram (Fig. 470), and in the following account of the operation.^ " In a state of nature, the flowers are incessantly visited for their nectar b}^ hive and other bees, various Diptera, and Lepidoptera. The nectar is secreted all round the base of the ovarium ; but a passage is formed along the upper and inner side of the flower by the lateral deflection (not represented in the diagram) of the basal portions of the filaments; so that insects invariably alight on the projecting stamens and pistil and insert their proboscides along the upper and inner margin of the corolla. We can now see why the ends of the stamens with their anthers and the end of the pistil with the stigma are a little upturned, so that they may be brushed by the lower hair}' surfaces of the insects' bodies. The shortest stamens, which lie enclosed within the calyx of the long- and mid-styled forms can be touched only by the proboscis and narrow chin of a bee: hence they have their ends more upturned, and they are graduated in length, so as to fall into a narrow file, sure to be raked by the thin intruding proboscis. The anthers of the longer stamens stand laterally farther apart and are more nearly on the same level, for they have to brush against the whole breadth of the insect's body. . . Now I have found no exception to the rule that, when the stamens and pistil are bent, they bend to that side of the flower which secretes nectar. . . . When nectar is secreted on all sides, they bend to that side where the structure of the flower allows the easiest access to it, as in Lythrum. ... In each of the three forms, two sets of stamens correspond in length with the pistil in the other two forms. When bees suck the flowers, the anthers of the longest stamens, bearing the green pollen, are rubbed against the abdomen and the inner sides of the hind legs, as is likewise the stigma of the long-st3-led form. The anthers of the mid-length stamens and the stigma of the mid-styled form are rubbed against the under side of the thorax and between the front pair of legs. And, lastly, the anthers of the shortest stamens and the stigma of the short-stj^led form are rubbed against the proboscis and chin ; for the bees in sucking the flowers insert only the front part of their heads into the flower. On catching bees, I observed much green pollen on the inner sides of the hind legs and on the abdomen, and much yellow pollen on the under side of the thorax. There was also pollen on the chin, and, it may be presumed, on the proboscis, but this was difficult to observe. I had, however,

1 All from Darwin, Forms of Flowers, 137-147, &c.

Digitized by LjOOQ IC

independent proof that pollen is carried

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