Introduction & Discovery

Microsorum scolopendria, now more frequently treated under the name Phymatosorus scolopendria in modern pteridophyte classifications, is a robust terrestrial-to-epiphytic fern of the Old World paleotropics whose fragrant rhizomes and handsome pinnately-lobed fronds have earned it a central place in Pacific Island horticulture, ethnobotany, and lei-making tradition. The species is distinguished from most of its Microsorum relatives by its habit: unlike the aquatic Java fern complex (Leptochilus pteropus and its cultivars), M. scolopendria is a true land plant, growing terrestrially in leaf litter, epiphytically on tree trunks, and lithophytically on exposed coral and volcanic rock, never as a submerged aquatic. Fronds are thick, coriaceous, dark glossy green, pinnately lobed into 5 to 15 pairs of elongate entire lobes 10 to 25 centimetres long, with a total frond length of 30 to 80 centimetres and width of 15 to 35 centimetres. The rhizome is long-creeping, 6 to 12 millimetres thick, covered in peltate brown scales, and produces a distinctive sweet, coumarin-like fragrance when bruised or cut, a fragrance sometimes compared to maile (Alyxia stellata, a native Hawaiian twining vine used in lei). In Hawaiian horticultural history this fragrance led to the widespread misapplication of the name laua'e to the introduced M. scolopendria, a misapplication that persists in nurseries and garden writing to this day despite the fact that true laua'e is the endemic Microsorum spectrum. Microsorum scolopendria is nonetheless one of the most useful tropical landscape ferns, tolerant of salt spray, periodic drought, full shade, dappled sun, poor soils, and exposed coral rock; it is widely planted around beach hotels, in coastal Japanese-style and Polynesian gardens, and as a groundcover beneath palms. The taxonomic history of the genus is complex: Microsorum sensu lato was long used as a convenient grouping, but molecular phylogenetic work including the Pteridophyte Phylogeny Group I synthesis of 2016 supports segregating the pinnately-lobed species including this one into Phymatosorus (or in some treatments, Phymatodes), making Phymatosorus scolopendria the name most likely to appear in current monographic work.

Discovery & Naming

Microsorum scolopendria was first formally described by the Swiss-German botanist Kaspar Georg Carl Reinwardt and/or his successors and students working in the Dutch East Indies and paleotropical herbaria during the early nineteenth century; the basionym and authority history is complex because the species was named, renamed, and reclassified across several genera over 150 years of pteridophyte systematics. The species originally appeared in genus Polypodium in early nineteenth-century descriptions, was placed in Phymatodes by Presl, in Microsorum following later generic revisions, and is currently treated in Phymatosorus by many contemporary pteridologists following the segregations supported by molecular phylogenetic analyses synthesized in the Pteridophyte Phylogeny Group I classification of 2016. The name Phymatosorus scolopendria reflects the pitted-sorus (phymato-sorus) character and the centipede-like (scolopendria) appearance of the pinnately-lobed fronds. The plant's horticultural introduction to Hawaii is better documented than its original botanical discovery: the species was imported as an ornamental in the late nineteenth or early twentieth century, reportedly valued for its coumarin-like fragrance reminiscent of native maile (Alyxia stellata), and was mistakenly equated with native laua'e (Microsorum spectrum) by nurserymen and gardeners who did not distinguish between the two. Naturalization in Hawaiian lowland forests was recognized by mid-twentieth century, and contemporary botanical literature now carefully distinguishes introduced M. scolopendria (laua'e haole, 'foreign laua'e') from native M. spectrum (true laua'e). Throughout this history the species' prolific spore production and tolerant habit have ensured its global distribution as both a wild plant and a cultivated ornamental; it now occurs in tropical conservatory collections worldwide.

Native Range & Distribution Map

Distribution map showing the native range of Microsorum scolopendria.

Biology & Frond Morphology

Microsorum scolopendria belongs to the genus Microsorum in the family Polypodiaceae, producing pinnately lobed to deeply pinnatifid, thick-textured coriaceous fronds with entire lobes 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 Microsorum scolopendria 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 Microsorum scolopendria 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 most common mistake with Microsorum scolopendria is over-watering, particularly in containers with dense water-retentive substrate; the rhizome prefers to dry somewhat between waterings and rots quickly when kept constantly wet. The second frequent mistake is deep burial of the creeping rhizome in soil or mulch; like most Microsorum relatives, the rhizome needs to rest at or just below the substrate surface with its dorsal face exposed to air. Burial causes rot. The third is full-sun exposure: tropical midday sun bleaches and scorches the fronds, and the plant performs far better in filtered light or partial shade. The fourth is planting in Hawaii or other sensitive Pacific island landscapes without considering invasiveness; in those jurisdictions native alternatives including Microsorum spectrum are the ethically and ecologically preferred choice. The fifth is misidentifying the plant as true laua'e: despite a century of nursery-trade conflation, Microsorum spectrum and Microsorum scolopendria are distinct species and the distinction matters in Hawaiian cultural and conservation contexts. The sixth is expecting the plant to survive any hard frost: a single night below zero Celsius destroys foliage, and sustained cold kills the rhizome. The seventh is heavy nitrogen fertilization, which produces soft tearable fronds more susceptible to wind damage and scale colonization. The eighth is attempting indoor culture in very dry centrally-heated rooms without humidification; ambient humidity below 30 percent stresses the plant and encourages scale outbreaks. The ninth is planting too close to walls and structures without accounting for the rhizome's vigorous creeping habit (which can exceed 15 centimetres of extension per year). The tenth is attempting to grow the plant submerged like a Java fern; it is not aquatic and drowns quickly under continuous submersion.

Seasonal Considerations

In continuously warm frost-free climates the plant grows year-round with only minor seasonal variation keyed to rainfall and temperature peaks. Spring and early summer see the strongest flush of new fronds, which emerge as pale-green circinate crosiers that quickly unroll. Summer is the peak growing period; keep irrigation consistent and watch for scale and mealybug colonization in sheltered plantings. Autumn brings gradual slowing and sori maturation; fertile fronds begin shedding spore in late summer through autumn depending on hemisphere. In marginal climates (USDA 10a to 10b fringe) autumn care includes preparing for possible cold snaps: frost cloth, mulch over the rhizome, and avoidance of late-season nitrogen fertilization that produces cold-tender soft growth. Winter in tropical climates is a cooler drier growing season with reduced fertilization; in subtropical climates nearer the frost line, winter is the critical period and protection from any freeze event is essential. Indoor specimens follow household rhythms: winter heating dries air and indoor humidifiers or pebble trays help; spring repotting is ideal when rhizomes have filled containers; summer benefits from moving pots to sheltered outdoor porches for stronger light and air movement. No true dormancy occurs; any period of reduced growth reflects reduced inputs (heat, water, nutrient) rather than photoperiodic dormancy. Spore collection for propagation is best timed to when sori turn a uniform dark brown, typically in late summer to mid-autumn depending on local climate.

Diseases & Pests

Common issues affecting Microsorum scolopendria 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

Microsorum scolopendria 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

Microsorum scolopendria 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

Phymatosorus scolopendria (Microsorum scolopendria) is widespread across the paleotropics and has not been formally assessed as threatened by the IUCN; it is not CITES-listed and faces no significant wild-collection pressure because horticultural supply is primarily from nursery-propagated stock. The species is one of the more common ferns of Pacific and Indian Ocean coastal and lowland ecosystems. The conservation conversation around this species runs in the opposite direction: in the Hawaiian Islands and some other Pacific island systems, M. scolopendria is itself a recognized invasive species displacing native ferns, most prominently the Hawaiian endemic Microsorum spectrum (true laua'e) and other native understorey components. The state of Hawaii through the Department of Land and Natural Resources and the Hawaii Invasive Species Council has published guidance discouraging further planting of the species near native forest and encouraging the use of native alternatives in landscaping. The Hawaii-Pacific Weed Risk Assessment rates the species as a high invasiveness risk. Elsewhere in its paleotropical native range the plant is a common forest-floor fern of no conservation concern. No Schedule 8, protected species, or endangered listing applies. Gardeners outside Hawaii may plant the species freely; within Hawaii the ethical choice is to favour the native M. spectrum or other locally native ferns over the introduced laua'e-in-name-only.

Collector Notes

For the fern collector Microsorum scolopendria is a foundational paleotropical species, easily obtained from tropical nurseries throughout its range and increasingly available as tissue-cultured stock in Europe and North America. The taxonomic question of Microsorum versus Phymatosorus is live and interesting: serious collectors maintain labels under both names to document the nomenclatural history. Several ornamental selections exist in the trade, most 'Monstrifera' or 'Crested' forms with forked and ruffled frond tips, and variegated forms with creamy-yellow streaking; these are relatively uncommon and warrant a place in a specialist collection. Herbarium specimens should be made from mature fertile fronds with clear sori development; the pitted-fertile character is diagnostic and preserves well. Rhizome segments should be dried or preserved in 70 percent ethanol for chemotaxonomic reference to the coumarin profile. For live collection, the species rewards a shallow broad container or a tree-branch epiphyte mount where the creeping rhizome can be observed across its full habit; a cramped upright pot misrepresents the plant. Comparative plantings alongside Microsorum spectrum (if available), Phymatosorus grossus, Drynaria quercifolia, and Phlebodium aureum make instructive displays of convergent and divergent polypodiaceous morphology. Hawaiian collectors should source from ethically responsible nurseries and avoid propagating into native forest zones. For travel, the rhizome tolerates short bare-root transport in damp paper towel, making it one of the easier ferns to exchange with other collectors under appropriate phytosanitary permits.

Ethnobotany & Cultural Significance

Microsorum scolopendria is among the most culturally significant ferns of the Pacific region. In Polynesian cultures from Hawaii and Samoa to Tonga, the Society Islands, and the Cook Islands, the fragrant rhizomes and pinnately-lobed fronds have traditional use in lei construction (particularly the Hawaiian haku and wili styles), in wreath-making for ceremonial occasions, in hair adornment, and as strewing material at weddings and hula performances. The coumarin-like fragrance of bruised rhizomes has been used to scent kapa (bark cloth) and coconut oils. Medicinal uses recorded in Pacific ethnobotanical literature include decoctions of rhizome for stomach ache, postnatal health tonics, and external washes for skin complaints; in Madagascar and East Africa, related traditional uses are recorded for rhizome preparations, though the chemistry underlying these applications is not fully characterized in modern phytochemical literature. In Tahitian tradition the plant is associated with Laka, the goddess of hula, though this association is specifically with the native species rather than with M. scolopendria; the confusion between native laua'e and the introduced wart fern is itself a recurring theme in contemporary Hawaiian cultural writing. In Southeast Asian food ethnobotany, young emerging fronds of this species are occasionally consumed as a green vegetable in parts of Malaysia and Indonesia, prepared by brief blanching or stir-frying, though far less commonly than Diplazium esculentum or Stenochlaena palustris. The rhizome fragrance, attributable to coumarin and related benzopyrones plus minor terpenoids, is the defining ethnobotanical character of the species and was the feature that attracted European and American horticulturalists to introduce the plant to Hawaii in the first place, with unintended ecological consequences that are still being reckoned with a century later.

Frequently Asked Questions