Question

Make a list of the different ways by which seeds are spread.

Answer 1

Plants create seeds that can grow into new plants, but they may not get enough light, water, or nutrients from the soil if the seeds only fall to the ground under the parent plant. Since plants are unable to walk around and carry their seeds to other locations, other techniques have been developed to disperse (move) their seeds.

Complete answer:
-Wind dispersal: Seeds are light and have feathery bristles from plants such as dandelions, swan plants, and cottonwood trees and can be carried by the wind for long distances. Some plants have 'winged' seeds, like kauri and maple trees. They're not floating free, just fluttering down to the ground. The seeds are simply blown around with wind dispersal, and land in all sorts of areas. These plants have to produce lots of seeds to help their chances that at least some of the seeds will land in a place suitable for growth.
-Water dispersal: There are seeds in many plants that use water as a means of dispersal. From the parent plant, the seeds float free. In estuaries, mangrove trees live. It will begin to root in the soil if a mangrove seed falls at low tide. They are taken away by the tide to grow somewhere else if the seeds fall into the sea. Water dispersal is also used by Kowhai trees. They have a hard coat of seeds that helps them to float down rivers and streams. That is one of the reasons why on-stream banks, kōwhai trees are commonly found.
-Animal Dispersal: In our woody forests in New Zealand, over 70% of plants have fleshy fruit that is consumed by birds. Chemicals in the digestive systems of our native birds tend to weaken the tough coats around these seeds. Birds also migrate far away from the parent plant and in their droppings scatter the seeds.
-Explosions: This seed dispersal process is not quite as thrilling as it may sound. Some plants have seed pods, such as peas, gorse, and flax, that dry out once the seeds are ripe. The pods break open when dry, and the seeds disperse. If you're lucky, when you walk by a gorse bush on a hot summer day you can hear the gorse seed pods popping open.
-Adaptation and dispersal of seeds: Adaptation is a process of evolution that enables an organism to make the most of its environment. An example of adaptation is seed dispersal. In Australia, fires are common, so some plants have adapted and become well adapted to make the most of it. Mangrove trees have floating seeds, making the most of their watery surroundings.

Note: Science is an endeavour to clarify the natural world. Evolution discusses how over long periods of time, groups of living organisms have evolved, such as how plants have developed multiple ways to spread their seeds.