name the seed that are dispersed by different agent
Answers
Plants make seeds that can grow into new plants. But plants cannot walk around and take their seeds to other places, they have developed other methods to disperse their seeds.
The most common methods are wind, water, animals, explosion and fire.
Wind dispersal -
With wind dispersal, the seeds are simply blown about and land in all kinds of places.
E.g - Seeds from plants like dandelions (flower develops seeds with fluffy parachutes attached to them), swan plants and cottonwood trees are light and have feathery bristles and can be carried long distances by the wind.
Seed dispersal by wind can be a gamble for the plant. It's hard to know where the seeds will ultimately end up, and if the conditions there will be suitable for germination. Thus, plants that use wind dispersal often make lots of seeds in hope that at least some will find the proper habitat.
• WATER DISPERSAL -
The seeds float away from the parent plant. E.g - Mangrove trees live in estuaries. If a mangrove seed falls during low tide and if the seeds fall in the water, they are carried away by the tide to grow somewhere else.
Kōwhai trees also use water dispersal. They have a hard seed coat that allows them to float down streams and rivers. That is one of the reasons kōwhai trees are commonly found on stream banks.
• Animal dispersal -
Fleshy fruit is eaten by the birds. Chemicals in our native 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.
E.g - The kererū, tūī and bellbird play an important role in seed dispersal.
Trees that produce the largest fruit – miro, tawa and taraire – rely on the kererū because it has such a large, wide beak to eat the fruit.
Animals - Some seeds have hooks or barbs that catch onto an animal’s fur, feathers or skin.
Plants like pittosporum have sticky seeds that can be carried away by animals. Humans can also spread seeds if they get stuck to our clothing or shoes.
•Explosions
Some plants, like peas, gorse and flax, have seedpods that dry out once the seeds are ripe. When dry, the pods split open and the seeds scatter.
• Fire
Plants have developed a way to help their seeds survive. There are some species of pine tree that require the heat from a fire before their cones will open and release seeds.
E.g - Banksias, eucalypts and other Australian plants also rely on fire.
The intensity and timing of the fire is important. It needs to be hot enough to trigger the cones to open, but if fires are too frequent, there is not enough time for the plants to grow big enough to make new seeds.