"Nine-Death Soul-Returning Yang-Restoring Long-Life Herb" - What plant is Selaginella tamariscina? Is it a fern or a gymnosperm?

Selaginella tamariscina comes from "Shennong Bencao Jing". "Diannan Bencao" calls it Yang-Restoring Herb, "Bencao Gangmu" calls it Long-Life Herb, "Fenlei Caoyaoxing" calls it Soul-Returning Herb. "Modern Practical Chinese Medicine" calls it Nine-Death Soul-Returning Herb. "Zhejiang Chinese Medicine Manual" calls it Water-Meeting Yang-Restoring Herb. So what plant is Selaginella tamariscina? According to Hunan plant records, Selaginella tamariscina is a fern, and its roots can separate from the soil on their own, curling up like a fist, moving with the wind, reviving upon meeting water, and the roots drill back into the soil to seek moisture. Because of its extremely strong drought tolerance, after long-term drought, as long as the root system is soaked in water, it can unfold again, hence its name. Selaginella tamariscina is both a foliage plant and can be used medicinally; it has hemostatic and astringent effects, and is notably effective in treating bloody stool, bloody urine, nosebleeds, and other conditions.

Pteridophyta is a major group of higher plants. It is also a relatively lower class among higher plants. They are often tall woody plants, forming large forests, flourishing in the late Paleozoic, and by modern times mostly herbaceous. Ferns can be divided into five subphyla: Psilophytina, Lycophytina, Isoetinae, Sphenophytina, and Filicophytina.

The leaves of general ferns serve both the function of photosynthesis to produce organic nutrients and the production of spores for reproduction (that is, monomorphic leaves). Ferns are the most ancient terrestrial plants. In the history of biological development, from 35000 million to 27000 million years ago, from the Late Devonian to the Carboniferous period, was the most flourishing period of ferns, when they were the main plant group on Earth; tall Lepidodendron, Sigillaria, Calamites, and tree ferns together formed ancient swamp forests. Beginning at the end of the Permian, ferns became massively extinct, and their remains were buried underground, forming coal seams.

There are about 12000 existing fern species, widely distributed around the world. Most are terrestrial, saxicolous, or epiphytic, and a few are hygrophilous or aquatic. They prefer shaded, moist, and warm environments.

In high mountains, plains, forests, grasslands, streams and gullies, rock crevices, and swamps, ferns all live, especially with a great variety of species in tropical and subtropical regions. China has about 2400 species, mainly distributed in the provinces and regions south of the Yangtze River.