Module: | Double Fertilization & Endosperm
Q78: Consider the following statements regarding heterostyly as an outbreeding device:
1. Heterostyly is a morphological mechanism where a single plant species produces flowers with styles and stamens of varying, unmatched lengths.
2. In the distylous plant Primula, the pin-eyed flower has a long style and short stamens, effectively preventing autogamy.
3. Because it relies on the delayed opening of the flower buds, heterostyly is primarily classified as a temporal outbreeding device rather than a physical one.
Which of the above statements is/are correct?
2. In the distylous plant Primula, the pin-eyed flower has a long style and short stamens, effectively preventing autogamy.
3. Because it relies on the delayed opening of the flower buds, heterostyly is primarily classified as a temporal outbreeding device rather than a physical one.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, but Statement 3 is a fundamental misclassification.
To enforce cross-pollination, evolution has produced varied barriers.
Heterostyly is a structural (morphological) barrier, heavily studied in Primula (primrose). This species exhibits distyly, meaning two forms of flowers exist in the population. "Pin" flowers have a highly elongated style protruding above deep-seated short stamens. "Thrum" flowers have a short, hidden style but highly elevated long stamens.
Causally, an insect visiting a pin flower gets pollen on a different part of its body than when visiting a thrum flower, making pollen transfer strictly successful only between opposite types.
Statement 3 is entirely false because heterostyly has nothing to do with the temporal timing of bud opening (which would be dichogamy); it is an absolute spatial, physical architecture that breaks the symmetry required for self-pollination.
To enforce cross-pollination, evolution has produced varied barriers.
Heterostyly is a structural (morphological) barrier, heavily studied in Primula (primrose). This species exhibits distyly, meaning two forms of flowers exist in the population. "Pin" flowers have a highly elongated style protruding above deep-seated short stamens. "Thrum" flowers have a short, hidden style but highly elevated long stamens.
Causally, an insect visiting a pin flower gets pollen on a different part of its body than when visiting a thrum flower, making pollen transfer strictly successful only between opposite types.
Statement 3 is entirely false because heterostyly has nothing to do with the temporal timing of bud opening (which would be dichogamy); it is an absolute spatial, physical architecture that breaks the symmetry required for self-pollination.