Q.Why do some plants have both chasmogamous and cleistogamous flowers ?

Pollination syndromes correlate flower traits with the pollinator's sensory abilities. Insect-pollinated (entomophilous) and bird-pollinated (ornithophilous) flowers are usually brightly coloured because those pollinators rely on vision. Bats, however, are nocturnal and rely mainly on smell and echolocation rather than colour vision, so bat-pollinated flowers are typically large, pale/dull in colour, open at night, and emit a strong (often musty or fermenting) fragrance to attract the bat in darkness. Such flowers also produce unusually large quantities of nectar and pollen, and the pollen itself is nutritious and edible, since …

Maize (Zea mays) is monoecious, bearing the male tassel at the top of the plant and the female ear (with long silky styles/silk) lower down on the stem. Its flowers are inconspicuous, lack nectar/fragrance, and produce enormous quantities of small, light, dry pollen grains, all classic adaptations for wind pollination (anemophily). The exposed, feathery silk of the female flower is well suited to intercept airborne pollen carried by wind currents, ensuring efficient cross-pollination in …

Geitonogamy is the transfer of pollen from the anther of one flower to the stigma of another flower borne on the same plant. Functionally it requires an external pollinating agent (wind or an animal pollinator) to carry the pollen, so it behaves like cross-pollination in mechanism. Genetically, however, since both flowers belong to the same plant (same genotype), the offspring produced are equivalent to those from autogamy (self-pollination within one flower). Xenogamy is true cross-pollination between genetically different plants, apogamy i …

Salvia (sage) flowers show a specialised 'lever mechanism' as a floral adaptation for entomophily (insect, chiefly bee, pollination). (1) Each flower has only two stamens, and in each stamen the connective (the tissue joining the two anther lobes) is greatly elongated and pivots at the point of attachment to the filament, creating two unequal arms: a long arm bearing a fertile, pollen-producing anther lobe that projects to block the mouth of the tubular corolla, and a short arm bearing a small, sterile anther lobe that lies deeper inside, near the nectar. (2) When a bee enters the flower in search of nectar, it pushes against and depresses the short sterile arm; because the connective acts as a lever pivoted at the filament, this downward push on the short arm causes the long arm to swing down, bringing the fertile anther lobe into contact with the bee's back/body, dusting it with pollen. When the same (pollen-dusted) bee visits another, older Salvia flower where the stigma has since matured and become receptive and positioned to touch the bee's back, cross-pollination is achieved. …