There are two shallow grooves in the center of the leaves of green kelp, the thicker part in the middle of the two grooves is the "middle belt", the edges on both sides are gradually thinner and have wavy wrinkles, the leaf base is wedge-shaped, the thick stage is oblate, and there is a cylindrical or oblate short handle below.

There are mucus cavities in the cortical cells of black kelp, which are arranged in a ring shape as 1-2 layers. The zoosporangium group is formed on the surface of the middle and lateral lobes of mature bacteria, and the fixator is composed of dichotomous branched rhizomes.

2. Different colors:

Green kelp is olive green and dark green after drying. Black kelp body is dark brown to dark brown, and it is black after drying.

3. Different lengths:

When green kelp is mature, its skin is banded, generally 2-6 meters long and 20-50 cm wide. The phyllodes in the Black Sea belt are flat and broad, slightly thick in the middle, deeply pinnate once or twice from both sides, with long tongues or long lobes and slightly wrinkled edges. Petiole stem, cylindrical or slightly flat, 4- 12 cm long and 3-8 mm in diameter.

4, the growth environment is different:

Green algae are marine organisms such as green algae attached to it, which grow in shallow water and have relatively neutral water quality. Black kelp has grown longer and thicker. It generally grows in the depths of the ocean, and the water quality is very salty.