Question

Aril helps in
A) Buoyancy to seed of Nymphaea to float in water
B) Dispersal in litchi by animals
C) None as it is an edible part
D) Both (A) and (B)

Answer 1

Hint: Aril is an additional covering found on some seeds. In most of the cases it is edible and in some aquatic plants it is present as a spongy layer.

Complete Answer:
- Aril is a fleshy appendage of seed and is mostly very colourful. Due to its striking colour it helps to attract the animals and thus helps in seed dispersal.
- Arils are often edible. So, the fruits having aril are eaten by the animals and the seeds which are not edible are passed out with the excreta unharmed. Such type of dispersal of seeds is known as endozoochory.
- In litchi fruit the fleshy edible part is aril that covers the dark brown inedible seed. The tasty and juicy aril of litchi attracts the animals towards the fruit and thus, helps in dispersal of the seeds.
- In water lily (Nymphaea) the fruit is a spongy berry which ripe under water. The fruit dehisces by the swelling of mucilage surrounding the seeds. Thus the seeds become free. The seeds are arillate. They are enclosed in an additional layer of cells (i.e. aril) which is a spongy layer having air spaces in between.
- Thus, it provides buoyancy to the seeds of water lily. The spongy aril entangles air bubbles and allows the seeds to float in water and move to other places with water currents. This type of seed dispersal is known as hydrochory.
- In litchi the edible aril helps in zoochory (seed dispersal by animals), and in water lily the spongy aril provides buoyancy to seeds.

Thus, the correct answer is D, i.e., Both (A) and (B).

Note: It arises from the funiculus or testa or from both after fertilization. It is regarded as the third instrument. Generally, it surrounds the seed either partially or completely.