What are the functions of the following sentences in the text?

The banyan tree is like a green umbrella with an open top. Say this sentence first:

1, but the image is vivid.

This is a metaphor, comparing a big banyan tree to a big umbrella with green velvet on the top, which vividly shows the appearance of a big banyan tree. The beautiful shape of banyan tree is vividly described in terms of color and shape, and the convenience brought by banyan tree is also written.

2. fortunately, it is written in detail.

This sentence makes the appearance of the big banyan tree very specific in the form of metaphor.

The article 1-3 describes the seaside scenery:

Paragraph 1 first introduces the general situation of the sea and blue sky in the seaside town.

The second paragraph complements the beautiful scenery of the seaside in the morning.

The third paragraph describes the lively scene on the beach by the sea. Mainly wrote (shells) and (fleet returning from fishing).

Paragraphs 4-6 of this article describe the beautiful scenery of this town:

The fourth paragraph describes the beauty of all kinds of trees in the courtyard, briefly describes coconut trees and olive trees, and describes eucalyptus and phoenix tree in detail.

The fifth paragraph depicts the beautiful scenery of the park. The focus is on banyan trees in the park.

The sixth paragraph depicts the beauty of the streets in the town, and describes in detail the roads paved with fine sand and the cleanliness of the roads.