Pellaea rotundifolia aka Button Fern

Pellaea rotundifolia is a small fern called button fern. Other names include New Zealand cliff brake and tarawera. It belongs to the Pteridaceae family. Its native range covers New Zealand and the Chatham Islands. There, it grows on cliffs, in rock cracks, and moist forests. NC State lists the same species as Hemionitis rotundifolia. This fern suits warm outdoor sites or indoor pots.

The plant forms a low rosette with arching, pinnate fronds. Garden plants reach about 0.5–1 foot [0.15–0.3 metres] tall and wide. RHS gives an upper size of 1.6 feet [0.5 metres] in both directions. Each frond may carry up to 30 small, round leaflets. These deep green leaflets have a slight gloss. Dark brown stalks bear pink scales and turn dark red with age. RHS describes fronds about 0.8 feet [0.25 metres] long. Most descriptions call the plant evergreen, though RHS also lists deciduous foliage.

Button fern has no flowers or fruit. It reproduces through spores rather than seeds. RHS advises sowing ripe spores at 13–18°C. NC State also describes division of the rhizome as a propagation method. The fronds give the plant its main garden value. It serves as a small accent in pots and hanging baskets. In warm areas, it suits rock gardens and wall cracks. RHS also recommends it for terrariums and bottle gardens. In cold areas, growers keep it indoors or in conservatories.

Give it filtered shade outdoors or indirect light indoors. RHS also allows sun with shelter from hot midday rays. Choose acidic soil that holds some moisture but drains well. Loam and sand suit it; NC State also reports clay tolerance. An acidic, humus-rich potting mix suits indoor plants. Water it regularly, though it can withstand some dry spells. It does not need the high humidity many ferns prefer. Shelter it from strong winds. Sources place it in USDA zones 9–11 and UK rating H2. Avoid prolonged freezing; RHS recommends dry winter mulch around the crown in frost-prone sites.

Care needs are low, with few reported pest or disease problems. It also resists rabbits. Remove dead fronds; it needs no other pruning. ASPCA lists it as non-toxic to dogs, cats, and horses. That pet-safety finding does not establish that people can eat it.