Dispersal Of Fruits And Seeds - SS3 Biology Lesson Note
The dispersal of fruits and seeds is an essential mechanism that allows plants to spread their offspring to new locations, reducing competition and increasing their chances of survival. There are various methods and agents involved in the dispersal of fruits and seeds. Here are some common dispersal mechanisms:
1. Wind Dispersal (Anemochory): Some plants have adapted to disperse their fruits and seeds through the wind. They produce lightweight structures, such as wings, hairs, or parachutes, that aid in wind dispersal. These structures help the fruits or seeds catch the wind and carry them away from the parent plant. Examples include dandelions, maples, and cottonwood trees.
2. Animal Dispersal (Zoochory): Many fruits have evolved to attract animals, which consume the fruits and disperse the seeds in their faeces. This process allows for long-distance dispersal and often benefits both the plant and the animal. Fruits may be brightly coloured, fragrant, or have edible and nutritious pulp to attract animals. Animals like birds, mammals, and reptiles play important roles in seed dispersal through their feeding habits. Examples include berries consumed by birds, fleshy fruits eaten by primates, and burrs attached to fur or feathers.
3. Water Dispersal (Hydrochory): Plants growing near water sources have adaptations for water dispersal. Fruits or seeds are buoyant and can float on water, allowing them to be carried away by currents to new areas. Coconut palms are an excellent example, with their large, floating coconuts dispersing over long distances through ocean currents.
4. Self-Dispersal (Autochory): Some fruits and seeds have mechanisms for self-dispersal. These mechanisms rely on the plant's own internal forces to disperse the seeds. Examples include explosive fruits that forcefully release seeds, like touch-me-not plants (Impatiens) and violets. Other examples include fruits with mechanisms that fling or catapult seeds away when they dry or split open.
5. Mechanical Dispersal: Certain fruits or seeds have structures or adaptations that allow them to hitch a ride on animals or passively disperse through external forces. They may have hooks, barbs, or sticky surfaces that attach to the fur or feathers of animals or the clothing of humans. Burdock and cocklebur are examples of plants that employ mechanical dispersal.
6. Human-Mediated Dispersal: Human activities have greatly influenced the dispersal of plants. Humans intentionally or unintentionally carry fruits or seeds to new locations, such as through agricultural practices, trade, or recreational activities. This human-mediated dispersal can lead to the spread of both native and non-native plant species.
(classnotes.com.in)
By utilizing various dispersal mechanisms, plants enhance their chances of colonizing new habitats, expanding their range, and ensuring the survival and genetic diversity of their species. Different plants have evolved specific adaptations to take advantage of the dispersal agents and environmental conditions in their respective ecosystems.