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. This genus was originally included in the related genus Lycopodium, from which it differs in having undifferentiated sporangial leaves, and the sporangia not formed into apical cones. The common name firmoss, used for some of the north temperate species, refers to their superficial resemblance to branches of fir (Abies), a conifer. As of 2020, two very different circumscriptions of the genus were in use. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Huperzia is one of three genera in the subfamily Huperzioideae of the family Lycopodiaceae. Most species in the subfamily are placed in the genus Phlegmariurus. Huperzia is left with about 25 species, although not all have been formally transferred to other genera. Other sources recognize only Huperzia, which then has about 340 species.
Morphology
The sporophytes of this genus have unbranched shoots that are generally upright and round in cross section. Horizontal stems are absent. The leaves are not borne in distinct ranks, and are usually somewhat lanceolate in shape. In some species, they vary in size according to the season in which they grow. Branchlets bearing gemmae – bud-like structures by which the plant reproduces asexually – occur among the leaves. The gemmae are triangular, with eight leaves in a constant pattern: four flattened into a plane and two large lateral leaves. The sporangia are kidney-shaped (reniform), occurring at the base of a leaf that is either unmodified or reduced. The roots are produced near the apex of shoots, and migrate downwards inside the cortex of the stem to emerge at soil level. The unbranched gametophytes are not photosynthetic, but rather subterranean and mycorrhizal.
The Flora of North America distinguishes Huperzia from the epiphytic tropical genus Phlegmariurus on the basis of differences such as the...
