卷柏（Selaginella），为石松门卷柏属的植物，属下约有700种卷柏，例子有二形卷柏、单子卷柏。如其他石松门植物，卷柏的叶子是只有一根叶脉的小型叶（microphylle），并以孢子作有性繁殖。江南卷柏是此属重要的模式生物。

Selaginella tamariscina (Beauv.) Spring ，又名「万年松」或「九死还魂草」，在干旱时根能自行从土壤分离，卷缩似拳状，随风移动，遇水而荣，根重新再钻到土壤里寻找水份。因其耐旱力极强，在长期干旱后只要根系在水中浸泡后就又可舒展，故而得名。

Selaginella is the sole genus of vascular plants in the family Selaginellaceae, the spikemosses or lesser clubmosses. This family is placed in the class Isoetopsida, distinguished from the sister group Lycopodiopsida by having scale-leaves bearing a ligule and by having spores of two types. They are sometimes included in an informal paraphyletic group called the "fern allies". S. moellendorffii is an important model organism. Its genome has been sequenced by the United States Department of Energy's Joint Genome Institute.