Huperzia serrata (Thunb.) Trevis.

Shoots ascending to erect from a decumbent base when mature, undivided or 1–4 times divided, up to 45 cm long. Homophyllous to gradually heterophyllous with slightly reduced sporophylls. Sterile leaves isophyllous, arranged in alternating subspiral whorls of 2–5 (usually 3), appearing spiralling, spreading to deflexed, thin and lax, often irregular in size on the same branch, oblanceolate to elliptic, abruptly acute, gradually tapering to base, 8–30 mm long, 1–3.5 mm wide, pale to dark green; margins serrate at least in distal half. Sporophylls similar to leaves but may be slightly reduced, often scattered and not restricted to terminal spikes. Sporangia 0.8–1.2 mm long, 1.5–2 mm wide, lunate, much broader than sporophyll bases.

Terrestrial in mesic forest where it forms localised sparse multi-plant colonies from bulbils. Habitat in Australia not recorded, but the locality from where the collection is purported to have been made is a rocky ridge line in montane cloud forest at 1500 m alt.

Used in China as a source of an alkaloid extract, Huperzine A, which is purported to have efficacy in the prevention of Alzheimer's disease (Ma & Gang 2008 and references therein).