STOP #11
STOP #11
STOP #11
Seed Dispersal
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Seed Dispersal
Plants make seeds that can grow into new plants, but if the seeds just fall to the ground under the parent plant, they might not get enough sun, water or nutrients from the soil. Because plants cannot walk around and take their seeds to other places, they have developed other methods to disperse (move) their seeds. The most common methods are wind, water, animals, and explosion.
Wind Dispersal
Have you ever blown on a dandelion head and watched the seeds float away? This is wind dispersal. Seeds from plants like dandelions, milkweed and Pterocarpus trees can be carried long distances by the wind. Pterocarpus winged’ seeds can flutter to the ground, but they can also float, allowing them to take root in the swamp. With wind dispersal, the seeds are simply blown about and land in all kinds of places. To help their chances that at least some of the seeds land in a place suitable for growth, these plants have to produce lots of seeds.
Water Dispersal
Many plants have seeds that use water as a means of dispersal. The seeds float away from the parent plant. Mangrove trees live in estuaries. If a mangrove seed falls during low tide, it can begin to root in the soil. If the seeds fall in the water, they are carried away by the tide to grow somewhere else. Certain palm trees also use water dispersal. They have a hard seed coat and are buoyant which allows them to float on oceans, and down streams and rivers.
Animal Dispersal
Most plants in our woody forests in Puerto Rico have fleshy fruit that are eaten by birds. Chemicals in the birds’ digestive systems help to weaken the tough coats around these seeds. Birds often fly far away from the parent plant and disperse the seeds in their droppings. The endangered Puerto Rican parrot once played an important role in seed dispersal. Its diet consists primarily of wild fruits, mostly fat-rich Sierra Palm seeds, which are a vital resource for this native bird. Some species of Puerto Rican bats are fruit eaters as well.
Explosions
This method of seed dispersal isn’t quite as exciting as it may sound. Some plants, like peas, and flax, have seed pods that dry out once the seeds are ripe. When dry, the pods split open and the seeds scatter.
