There are several varieties of purple fern.

Does the subject want to ask, "How many species of Dryopteris are there?" 15 species.

1, there are only three genera in Osmundaceae 1 family: Osmunda, Dryopteris and Pteris, the latter two are only found in the southern hemisphere, Osmunda has 15 species, which are distributed in temperate and tropical regions of the northern hemisphere, and there are 8 species in China, which are the most common.

2. Osmundaceae is a kind of plant with thick rhizome, erect or procumbent, and the petiole base is covered with persistent leaves, which is often trunk-shaped. It is one of the famous bracken varieties, which was called Wei by the ancients. The leaf cluster is at the top, and the type 2 or feather on the same leaf can be divided into fertile and sterile. Adult fertile leaves (or pinna) have no chlorophyll, narrow strength and sporangium below. There are only mucus villi in childhood, but the sporangium wall is only composed of one layer of cells, which is easy to crack and beneficial to spore diffusion, which is possessed by ferns with earlier evolution. Therefore, it is also listed as the primitive Spodoptera litura. Most of them are born in acidic soil near forests, ridges or streams.