Introduction & Discovery

Selaginella martensii is among the most distinctive spikemosses in cultivation and one of the most widely sold tropical members of the genus, instantly recognisable by its erect tufted habit and the extraordinary stilt-like aerial rhizophores that lift the base of the stem several centimetres above the substrate in a miniature mangrove architecture. Named for the Belgian botanist Martin Martens, who with Henri Galeotti collaborated on the early floristic exploration of Mexico, the species was formally described in the mid nineteenth century and has been a staple of conservatory horticulture since the Victorian glasshouse era. Unlike the prostrate mats of Selaginella kraussiana or the iridescent blue of Selaginella uncinata, martensii builds a small upright thicket 15 to 30 centimetres tall, pseudo-dichotomously branched into flattened green sprays resembling cut parsley or fresh young conifer shoots. The species belongs to Selaginellaceae, a family of lycophytes and not of true ferns, and it displays every diagnostic feature of the group: single-veined microphylls arranged in four ranks, a minute membranous ligule on the adaxial base of each leaf, rhizophores in place of true primary roots at the stem nodes, and heterosporous strobili bearing both large megaspores and small microspores. The stilt rhizophores in martensii are especially prominent and are a widely-used textbook example of this unique lycophyte organ. In its native Mesoamerican understorey the species forms small colonies on moist shaded banks, limestone seep faces, and mossy streamside terraces from Veracruz through Guatemala to northern Costa Rica. In temperate cultivation it is strictly a tender plant for warm indoor culture, and is best grown in a terrarium, bottle garden, paludarium, or warm humid conservatory where ambient humidity reliably exceeds 60 percent and temperatures do not drop below 12 degrees Celsius. Several cultivars are long-established in horticulture, most the variegated Watsoniana with its frosted cream-white branch tips, the golden-foliaged Aurea, and the compact Jori, each of which propagates easily from stem-tip cuttings and offers a slightly different aesthetic within the same cultural regime.

Discovery & Naming

The genus Selaginella was established by the French botanist Palisot de Beauvois in 1804 and formally published in his Prodrome des cinquième et sixième familles de l'Aetheogamie of 1805, as a segregate from the Linnaean Lycopodium, to accommodate the heterosporous ligulate species. Selaginella martensii was described in the mid nineteenth century by the Belgian botanist Antoine Laurent Apollinaire Fée and in allied literature of the period, and is widely associated with the name of Martin Martens, the Belgian professor of botany at Louvain who with the collector Henri Galeotti undertook the important floristic investigation of Mexico documented in the Mémoires sur les fougères du Mexique (1842) and subsequent works. The specific epithet commemorates Martens's contribution to Mesoamerican pteridology. The species entered European horticulture during the second half of the nineteenth century and was widely grown in British and Continental conservatories by the 1870s; the variegated cultivar Watsoniana was introduced by the nineteenth-century nursery firm Watson of Killiney, near Dublin, and is referenced in late-Victorian horticultural periodicals. Twentieth-century pteridological monographs by Alston and others placed martensii in the section Stachygynandrum of Selaginella. The species has been a convenient teaching plant in botanical anatomy courses for more than a century, especially for demonstrating the stilt-rhizophore habit, the microphyll ligule, and the heterosporous strobilus. Twenty-first-century molecular phylogenies based on multiple chloroplast and nuclear markers have confirmed its placement within a New World clade of ornamental Stachygynandrum species, closely allied to several other Mesoamerican and Caribbean taxa.

Native Range & Distribution Map

Distribution map showing the native range of Selaginella martensii.

Biology & Frond Morphology

Selaginella martensii belongs to the genus Selaginella in the family Selaginellaceae, producing evergreen, erect to weakly ascending, tufted lycophyte producing upright leafy stems rather than true fronds. unlike the prostrate mat-forming selaginella kraussiana or s. uncinata, s. martensii develops distinctive stilt-like aerial rhizophores that emerge from the lower stem nodes, descend obliquely, and anchor into substrate, giving mature specimens a characteristic miniature mangrove appearance. stems reach 15 to 30 centimetres tall and branch pseudo-dichotomously into flattened frond-like sprays of bright fresh green foliage. microphylls are arranged in four ranks on each branch: two lateral rows of larger obliquely-spreading ovate leaves and two median rows of smaller appressed acuminate leaves. each microphyll bears a minute membranous ligule on its adaxial base, diagnostic of the family. strobili are small, quadrangular, and terminate short lateral branchlets. fronds that unfurl from coiled fiddleheads (croziers). Like all ferns, it reproduces via spores borne on the underside of fertile fronds rather than flowers and seeds, and its life cycle alternates between a dominant sporophyte (the visible plant) and a small, short-lived gametophyte stage.

Reproduction & Propagation

Propagation of Selaginella martensii can be achieved through several methods:

• Spores: Collect ripe spores from the underside of fertile fronds, sow on sterilised peat or peat/perlite mix. Do not cover. Keep humid and in bright indirect light. Prothalli (gametophytes) typically develop in 4–12 weeks, and young sporophytes appear after a further 2–6 months.
• Division: Mature clumps with multiple crowns or creeping rhizomes can be divided in spring as new fronds emerge.
• Rhizome cuttings / offsets: Epiphytic genera (Davallia, Polypodium, Phlebodium) can be propagated from 5–10 cm rhizome segments with at least one frond and visible roots.

Cultivation & Substrate

Successful cultivation of Selaginella martensii depends on matching three conditions to its natural habitat: consistent moisture without waterlogging, a humus-rich yet well-drained substrate, and the correct light level for its frond type — whether dappled woodland shade, bright filtered light, or, for a handful of rock ferns, direct sun.

Common Mistakes to Avoid

The commonest fatal error is allowing the substrate to dry through, even briefly, during a hot spell or a busy period; foliage browns irreversibly within hours. A second common mistake is the opposite: leaving the pot standing in a saucer of water so that rhizophores and the stem base remain waterlogged, producing rapid basal rot. A third is growing the plant in typical heated-room humidity of 30 to 40 percent, which causes steady stem-tip browning and slow decline; a terrarium, humidifier, or pebble tray is effectively mandatory. A fourth is using hard mineral-rich tap water; carbonates accumulate on the foliage and in the substrate, bleaching the plant and raising the pH into a range it dislikes. Switch to rainwater or filtered water. A fifth is siting the plant in direct sun, which scorches foliage within hours. A sixth is over-feeding with standard-strength liquid fertiliser, which causes salt build-up and stem-tip burn; quarter strength is the safe maximum. A seventh is burying the stilt rhizophores completely under fresh substrate at repotting, which leaves the lower stem waterlogged; leave the stilts exposed. An eighth is expecting the plant to be the iridescent blue of S. uncinata; martensii is always a fresh green or, in Watsoniana, a cream-variegated green. A ninth mistake is attempting to grow it outdoors in temperate gardens; it is strictly a tender indoor or glasshouse plant.

Seasonal Considerations

Spring (March to May): active growth resumes as days lengthen and indoor temperatures rise. Repot if pot-bound, top up substrate around exposed stilt rhizophores, and begin quarter-strength monthly liquid feeding. Take stem-tip cuttings for propagation; this is the best season for successful rooting. Monitor for fresh pest arrivals as houseplants move around. Summer (June to August): peak growth under warm humid conditions. Water frequently, mist daily in dry indoor air, and keep the plant out of hot south- and west-facing windows. Group with other tropical foliage plants for mutual humidity boosting. Avoid opening windows near the plant during dry heatwaves. Autumn (September to November): growth slows modestly as daylength shortens; reduce feeding toward the end of the season. Move the plant away from cold windows as outdoor temperatures drop. Check for fungal patches after autumn humidity peaks. Winter (December to February): the most challenging season in heated temperate homes. Maintain humidity with a tray, humidifier, or transfer to a terrarium. Reduce watering slightly but never allow drying. Keep away from heating vents, radiators, and cold window glass. Supplement natural light with a grow lamp if the winter photoperiod is very short. Avoid any feeding and any drastic repotting during winter.

Diseases & Pests

Common issues affecting Selaginella martensii in cultivation:

• Root/rhizome rot: Caused by waterlogged substrate, compacted soil, or overwatering in cool weather. Ensure the growing medium is well-aerated and never let pots sit in standing water for prolonged periods.
• Fungal leaf spot & Botrytis: Brown or grey blotches appear in stagnant, overly humid conditions. Improve air circulation, remove affected fronds, and avoid wetting foliage late in the day.
• Scale insects & mealybugs: The most common fern pests, hiding on stipes and frond undersides. Wipe off with a cotton swab dipped in diluted isopropyl alcohol, or treat with horticultural soap. Many chemical pesticides scorch fern fronds — always test on one frond first.
• Spider mites: Fine webbing and stippled fronds, common in dry indoor air. Raise humidity and rinse fronds regularly with tepid water.
• Frond browning (tip burn): Caused by dry air, direct hot sun, fluoridated or chlorinated tap water (especially in Nephrolepis, Calathea-loving filmy ferns), or soluble-salt build-up from fertiliser. Flush the pot with rainwater and reduce feeding.

Indoor Growing & Terrariums

Selaginella martensii can be grown indoors as a houseplant or terrarium subject when its humidity and light requirements are met.

Indoor Setup

• Light: Bright indirect light — an east- or north-facing window, or 30–60 cm under an LED grow light (10–12 hours/day). Most ferns scorch in direct midday sun.
• Humidity: 50–80%. Group plants, stand pots on a pebble-and-water tray, or run a humidifier; misting alone rarely raises ambient humidity enough.
• Temperature: 16–24°C (60–75°F) for most indoor species; avoid cold drafts and hot radiators.
• Substrate: Peat-free potting mix with added perlite and orchid bark for drainage; epiphytic genera (Platycerium, Davallia) grow best mounted on bark or in a bark-heavy orchid mix.
• Water: Keep consistently moist but never waterlogged. Let the top 1–2 cm of substrate dry slightly between waterings in winter.
• Air circulation: A gentle fan discourages fungal leaf spot without drying out the fronds.

Landscape & Garden Use

Selaginella martensii can be used in the garden wherever its hardiness and habitat preferences are matched. Ferns are classic choices for shaded borders, woodland gardens, stumperies, rockeries, stream-side plantings, and ground-cover under trees.

Landscape Tips

• Companions: Hostas, Astilbe, Heuchera, Tiarella, Epimedium, hellebores, snowdrops and other shade-tolerant perennials are classic partners.
• Soil preparation: Incorporate leaf mould or composted bark to improve moisture retention and mimic a forest floor.
• Mulching: A 3–5 cm mulch of chipped bark or leaf litter protects the rhizomes, conserves moisture, and slowly releases nutrients.
• Watering: Establish new plantings with regular deep watering during the first growing season; most hardy ferns need only occasional supplemental irrigation once established.

Conservation & Collector Notes

Selaginella martensii has not been formally evaluated against IUCN Red List criteria at global scale and is not listed in CITES or comparable international trade conventions. Within its native range it remains widespread and locally common in appropriate habitat, and no regional red-data treatment classes it as threatened. The species is considered to be of Least Concern by default by most conservation assessors, with the principal long-term concern being deforestation and fragmentation of Mesoamerican lowland and lower montane forest rather than direct exploitation. It does not appear in the commercial horticultural trade from wild-collected material in significant quantities; all cultivated stock derives from long-established nursery clones, divisions, and tissue culture. Invasive behaviour outside its native range is minor and largely confined to local escapes around botanic gardens and conservatories in Florida, Hawaii, and a few tropical islands, none of which rise to the level of environmental concern that applies to Selaginella kraussiana. Habitat loss remains the single most important future threat: the limestone understorey habitats on which the species depends are under sustained pressure from agricultural clearance, cattle ranching, limestone quarrying, and road development through Mesoamerican karst landscapes. Ex situ conservation is assured by the species' widespread cultivation in botanic gardens around the world. No dedicated conservation action plan exists but the species would benefit indirectly from any measure protecting Mesoamerican moist forest.

Collector Notes

For specialist collectors Selaginella martensii offers a compact and rewarding subject whose cultivars and provenances merit organised display. The type form has plain fresh-green foliage and vigorous stilt-rhizophore development. The cultivar Watsoniana, named for the Victorian English nurseryman Watson of Killiney, is the most widely grown variegated Selaginella in horticulture and is characterised by cream-white tips on the branch ends, most pronounced on actively growing shoots under moderate light. The cultivar Aurea has golden-yellow foliage and grows a little less vigorously than the type. The cultivar Jori is a compact more densely branched selection. Wild-provenance accessions from Mesoamerican botanic-garden collecting expeditions are rare but do exist in specialist conservatory collections; the pteridophyte collections at Kew, the Missouri Botanical Garden, and selected European botanic gardens hold documented wild material. Because the species propagates so readily by cutting, exchange between collectors is easy and no specialist equipment is required. A compact collection of the type form alongside Watsoniana and Aurea occupies no more than a single terrarium or a shelf of three small pots. Label each clone clearly to avoid confusion, since cultivar misidentification is common in the general nursery trade, and keep notes on propagation dates and provenance for any wild-origin material.

Ethnobotany & Cultural Significance

Specific ethnobotanical documentation for Selaginella martensii is limited relative to East Asian resurrection members of the genus. Mesoamerican ethnobotanical surveys occasionally list the species among understorey plants collected for minor medicinal decoctions used locally for skin complaints, minor wounds, and cooling topical preparations, although such reports are scattered and the species is not a principal component of any well-documented traditional pharmacy. Phytochemical studies of the genus Selaginella have identified a distinctive class of dimeric compounds called selaginellins and a suite of biflavonoid compounds (including amentoflavone, hinokiflavone, and related structures); these are characteristic of the family and have been detected in several species including martensii. Some show antioxidant and cytotoxic activity in laboratory assays but none is in clinical use. The dominant cultural role of S. martensii is horticultural: the species has been grown in European and North American conservatories for more than 150 years, is a feature of nineteenth-century glasshouse-horticulture literature, and remains a benchmark tropical Selaginella in terrarium culture. Vivarium hobbyists growing dart frogs, small lizards, and other tropical amphibians commonly include martensii as a naturalistic understorey element. The cultivar Watsoniana is a stalwart of historic botanic-garden collections and is figured in several classic twentieth-century houseplant manuals.

Frequently Asked Questions