Selaginella martensii, an evergreen perennial fern that is native to South America and New Zealand, is named “frosty fern” because of its beautiful white-colored leaves and it is used as an ornamental plant. Efficient propagation methods for this species have not been developed. We aimed to develop an efficient propagation method for S. martensii through in vitro culture. We investigated culture conditions that are suitable for shoot-tip proliferation and growth. The optimum shoot-tip culture conditions were determined while using Murashige and Skoog (MS) medium (quarter, half, full, or double strength) and macronutrients (sucrose and two nitrogen sources) at various concentrations. In MS medium, the shoot tips formed a maximum of 6.77 nodes per explant, and each node formed two new shoot tips (i.e., 26 or 64 shoot tips). When using branching segments containing an angle meristem, the shoot-to-rhizophore formation ratio could be controlled by medium supplementation with plant-growth regulators. Sporophytes that were grown from shoot tips in vitro were acclimated in ex vitro soil conditions and successfully survived in the greenhouse. Numerous shoot tips could be obtained from in vitro-grown sporophytes and be proliferated ex vitro to produce a large number of plants. This method provides a way of shortening the time that is required for producing a large stock of S. martensii planting material.

Selaginella tamariscina is a medicinal plant that contains a variety of plant secondary metabolites; however, it is currently being collected indiscriminately from its native habitats. Hence, we have developed an efficient propagation method for S. tamariscina. Explants grown in vitro were cultured in Murashige and Skoog medium of various strengths (1/16–2x), and the highest number of sporophytes (65.7) were obtained with 1/4x MS medium. Culturing explants at various lengths (3–12 mm) for 12 weeks indicated 12 mm as the most appropriate size for sporophyte propagation. We then evaluated various concentrations of individual components, sucrose (0–5%), total nitrogen (7.5–30 mM), nitrogen ratio (3:0–0:3), and agar (0.6–0.8%), in the 1/4x MS medium for explant growth for 12 weeks. The maximum number of sporophytes were formed in media containing 3% sucrose, 15 mM nitrogen, and 0.6% agar, with a nitrogen ratio of 1:2. The propagated S. tamariscina was then acclimatized in a controlled environment to improve survival in an external environment. These results demonstrate the effective conditions for in vitro mass propagation of S. tamariscina, finding that methods utilizing sporophytes were more efficient than conventional propagation methods and yielded numerous plants in a short period.