Reason: the pods are exposed to the sun, and when they snap, the pods explode, allowing the beans in the pods to scatter and take root.

Original text:

If a child has grown up, he has to say goodbye to his mother and go to all four corners of the world.

Cows and horses have feet, birds have wings, and what means do plants use to travel?

Mother Dandelion prepared a parachute and gave it to her doll. As soon as the wind blew gently, the children set off in droves on the wind.

Mother Cthulhu had a good idea; she dressed her children in spiked armor. As long as they hung on to the animal's fur, the children were able to go to the fields and hollows.

Mother Pea had an even better idea, she let the pods sit in the sun, and when they snapped, the pods exploded, and the children jumped and skipped away from their mother.

There are many, many ways that a mother plant can do this, so look closely. There is so much knowledge there, and careless children don't get it.

Expanded:

"The plant mother has a way" This article uses anthropomorphism, the scientific knowledge in the form of rhyming vivid image, the language is catchy, is a piece of science works that will never tire of reading.

Pods of general knowledge:

Pods developed from a single carpel pistil, in the process of development along the carpel healing at the formation of the ventral suture line, and the ventral suture line opposite to the formation of the dorsal suture line, some pods in the maturity of the ventral suture line and the dorsal suture line along the dehiscence (after maturity, split into two), the seeds disintegration, pods generally contain more than one seed along the ventral suture line, and occasionally only a seed of pods, such as purple acacia, water yellow skin.

The pericarp of the pod is diverse, with some species having a smooth surface like peas, some species having a hairy surface like soybeans, and some having a fleshy pericarp like acacia, with the pod sepals persistent and inserted on the side of the fruiting tip.

Some species have pods that break off at maturity in sections called knobbly pods, such as the leguminous early-plant species of the mountain locust genus (flywing grass). Others, such as phoenix tree, yellow butterfly, goat's hoof, prickly pear, acacia, buffalo bark, shield pillar wood, and abalone, are all pods.

Baidu Encyclopedia - Bean Pods

Baidu Encyclopedia - Plant Mom Has a Solution