Button Fern

Pellaea rotundifolia is endemic to New Zealand, where it is widely distributed across both the North and South Islands, as well as Stewart Island.

• Found naturally in coastal to lowland regions, occasionally extending into lower montane zones
• Grows in a range of habitats from rocky outcrops and cliff faces to open scrubland and forest margins
• The genus Pellaea comprises approximately 40–50 species distributed across tropical and warm-temperate regions of the Americas, Africa, Australia, and New Zealand
• New Zealand's geographic isolation has contributed to the evolution of unique fern lineages, with Pellaea rotundifolia being one of the country's most recognizable native ferns
• The species was first formally described in the 19th century and has since become a staple in horticulture worldwide

The Button Fern is a small to medium-sized evergreen fern, typically reaching 15–45 cm in height with a similar spread.

Rhizome & Stipes:
• Rhizome is short-creeping to ascending, covered with narrow, dark brown to reddish-brown scales
• Stipes (leaf stalks) are slender, dark brown to nearly black, and somewhat wiry, measuring 5–20 cm in length
• Rachis (central axis of the frond) is straight to slightly arching, dark and glossy

Fronds:
• Fronds are pinnate to bipinnate, linear-oblong in overall outline, typically 10–45 cm long and 3–7 cm wide
• Pinnae (leaflets) are distinctive — nearly round to broadly oblong, 5–15 mm across, with a leathery, dark green texture
• Pinnae are arranged in opposite to sub-opposite pairs along the rachis, giving the frond a neat, symmetrical appearance
• Upper surface is glossy dark green; lower surface may be slightly paler
• Margins are entire to slightly wavy; each pinna is attached to the rachis by a small stalk (petiolule)

Sori:
• Sori are borne along the margins of the undersides of the pinnae, protected by the reflexed leaf margin forming a false indusium
• Sori are continuous along the leaf edge rather than in discrete clusters
• Spores are brownish when mature, released for wind dispersal

Pellaea rotundifolia occupies a notably different ecological niche compared to most ferns, which typically require constantly moist, shaded environments.

• Naturally found in dry, exposed rocky habitats including cliff faces, scoria fields, and stony ground
• Tolerates full sun to partial shade in its native range — unusual among ferns
• Can withstand periods of drought by curling its pinnae to reduce water loss, then rehydrating when moisture returns
• Often grows in thin soils with excellent drainage, including crevices in volcanic rock
• In New Zealand, it is commonly associated with coastal and lowland ecosystems, including open Leptospermum (manuka) scrubland
• Its drought tolerance is attributed to the thick, leathery texture of its pinnae, which reduces transpiration

Reproduction:
• Reproduces via spores dispersed by wind
• Spores germinate into heart-shaped prothalli under moist conditions
• Like all ferns, requires a film of water for sperm to swim from antheridia to archegonia during sexual reproduction
• Can also spread slowly via its creeping rhizome

The Button Fern is widely regarded as one of the easiest ferns to grow as a houseplant, owing to its tolerance of lower humidity and drier soil conditions compared to most of its relatives.

Light:
• Prefers bright indirect light but tolerates lower light levels than many ferns
• Can handle some direct morning sun; avoid harsh afternoon direct sunlight, which may scorch the pinnae
• Adapts well to indoor lighting conditions

Soil:
• Requires well-draining soil — a standard potting mix with added perlite, pumice, or coarse sand works well
• Does not tolerate heavy, waterlogged soils; good drainage is essential
• A slightly acidic to neutral pH (6.0–7.0) is ideal

Watering:
• Allow the top layer of soil to dry out slightly between waterings — unlike most ferns, it does not need constantly moist soil
• Overwatering is the most common cause of failure; soggy roots lead to rot
• Reduce watering frequency in winter during the plant's slower growth period

Temperature:
• Optimal range: 15–24°C
• Tolerates cooler temperatures down to approximately 7°C for short periods
• Avoid placing near heating vents or radiators, which can desiccate the foliage

Humidity:
• Tolerates average indoor humidity (30–50%), unlike most ferns that require >60%
• Occasional misting is beneficial but not essential

Propagation:
• Division of the rhizome during repotting is the most reliable method
• Spore propagation is possible but slow and requires sterile conditions

Common Problems:
• Brown, crispy pinnae → underwatering or excessively dry air
• Yellowing or blackening fronds → overwatering or root rot
• Mealybugs and scale insects may occasionally infest the plant
• Leggy, sparse growth → insufficient light