Huperzia is a genus of lycophyte plants, sometimes known as the firmosses or fir clubmosses; the Flora of North America calls them gemma fir-mosses.

The common name firmoss, used for some of the north temperate species, refers to their superficial resemblance to branches of fir (Abies), a conifer.

The roots are produced near the apex of shoots, and migrate downwards inside the cortex of the stem to emerge at soil level.

[2] The Flora of North America distinguishes Huperzia from the epiphytic tropical genus Phlegmariurus on the basis of differences such as the former's complex and specialized shoots, the gemmae and the branchlets on which they are borne, and the unbranched gametophytes.

[3] A phylogenetic study in 2016, employing both molecular and morphological data, concluded that either a one-genus or a three-genus division of the subfamily produced monophyletic taxa.

[4] The following hybrids have been described:[4] As circumscribed in the PPG I classification, Huperzia is distributed in temperate, arctic and alpine habitats, including mountains in tropical Asia.