Question

Spear grass (Aristida) is dispersed by
A. Air
B. Animal
C. Water
D. Explosive mechanism

Answer 1

Hint: The seed dispersal is a process by which plants or trees transport or move their seed to another location. It is important to note that the seeds of spear grass have spikes which are also known as hooks.

Complete answer: Seed dispersion is the process of movement or transport of seeds to different locations away from the parent plant. It is important for the proper growth of the new plant as it doesn’t have to compete with its parent for resources like sunlight, water and nutrients. It is broadly divided into two types: biotic and abiotic medium. Biotic medium includes transfer by animals and is known as zoochory. This can be in many forms, from fruit consumption and defecation of seed to attaching to the animals’ body. Speargrass uses this method for seed dispersal. Abiotic medium includes transport by wind, water, gravity, or explosive mechanism. Seeds of pappus and maple use wind for seed dispersal, while water lily and palm trees use water for the same. Fruits like coconut, and apple which is big in size use gravity for seed dispersal. Seeds of witch hazel use explosive methods.
Speargrass or Aristida is a type of grass generally grown during the summer season. Its seeds are spines or hooks, due to which it entangles in the animal’s fur and is transported.
Hence, the correct option is option B.

Note: The seed dispersal is a very important phenomenon for better growth of a new plant. To ensure this some trees like the black walnut tree produce chemicals in the soil and prevent any tree or plant growth in its vicinity.