Plants in nature are colorful. The poems describing plants in ancient poetry are as follows

(1) Algae plants mostly live in water, and the plants described in the poem as "the West Lake returns in spring and the riverside is as green as blue" belong to algae plants;

(2) The heavy snow overwhelms the pine trees, which are tall and straight, and the pine trees in the poem are gymnosperms;

(3) The next day, the lotus leaves are infinitely green, and the lotus flowers in the sun have different colors. The lotus in the poem belongs to angiosperms;

(4) When I was in Qiu Lai on September 8th, I killed a hundred flowers. The description in the poem is that chrysanthemum belongs to angiosperms.

So, the answer is: (1) algae; (2) gymnosperms; (3) angiosperms; (4) Angiosperms.