. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. 238 PRACTICAL COURSE IN BOTANY ..<=- Charles Darwin, proved by experi- ment that the seeds produced by polli- nating a dimorphous flower with its own pollen, or with pol- len from a flower of similar form, are of 348 349 349 ⢠f â -,-, Figs. 348-350. â Three forms of loosestrife (Lyth- very interior quality rum salicaria). to those produced by impregnating a long-styled flower with pollen from a short-styled one, and vice versa. 271. "Nature abhors self-fertilizat
. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. 238 PRACTICAL COURSE IN BOTANY ..<=- Charles Darwin, proved by experi- ment that the seeds produced by polli- nating a dimorphous flower with its own pollen, or with pol- len from a flower of similar form, are of 348 349 349 ⢠f â -,-, Figs. 348-350. â Three forms of loosestrife (Lyth- very interior quality rum salicaria). to those produced by impregnating a long-styled flower with pollen from a short-styled one, and vice versa. 271. "Nature abhors ; â These are the three principal methods by which nature provides against self-fertilization. Other cases occur in which the relative position of the two organs is such that self-pollination is difficult, or impossible, as in the iris and bear's grass; or the pollen may be incapable of acting on the stigma of the flower that produced it. This aversion to self-fertilization is so great that many flowers, even when capable of it, will give preference to the pollen of another plant of the same kind, if dusted with both. From his observations on the behavior of plants in reference to this function, Charles Dar- win drew the conclusion that "Nature abhors perpetual self-fertilization.'' 272. Cleistogamic flowers. â Apparent exceptions to this rule are the hidden flowers found on certain plants which seem to have been constructed with a special view to self- fertilization. They are called cleistogamic, or closed, because they never open, but are fertilized in the bud; and those of the fringed polygala do not even rise above ground at all. Flowers of this kind can be found on several species of violet, concealed under the leaves, close to the ground; and the flowers of the peanut, found in the same situation, while they open slightly, are close-fertilized and practically cleisto-. Please note that these images are extracted from scanned page images that may have b
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