Button Fern Identification Guide
Identify the Button Fern (Pellaea rotundifolia), a low-growing fern with distinctive round, button-like leaflets along wiry dark stems.
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Key Identifying Features
The Button Fern (Pellaea rotundifolia) is unusual among ferns for its small, rounded, leathery leaflets that look like a row of buttons strung along a wiry stem. It is a compact, low, spreading fern from New Zealand.
- Small round to oval, button-like leaflets
- Dark, wiry, reddish-brown stems (rachises)
- Low, arching to trailing fronds, 6-12 inches long
- Leathery, dark green leaflets, not lacy or feathery
Leaves & Stems
Each frond is once-pinnate, with 10-20 pairs of nearly circular leaflets spaced along a slender stem. The leaflets are about a half-inch wide, thick and leathery, deep green, and held fairly flat. New leaflets near the tip start oval and become rounder with age.
The rachis and stipe are wiry and dark reddish-brown to nearly black, a key feature that contrasts with the green leaflets. Fronds arch outward and trail over pot edges, giving a low, ground-hugging look. The overall texture is firm and almost crisp, not soft.
Flowers & Fruit
Button Fern reproduces by spores, not flowers. The sori run in a continuous band along the rolled-under margins of the leaflets, partly hidden by the curled leaf edge, typical of the Pellaea genus. There are no seeds, fruit, or blooms.
How to Tell It Apart from Look-Alikes
- Lemon Button Fern (Nephrolepis cordifolia 'Duffii'): Has rounder, frillier leaflets crowded closely along a green stem and a faint lemon scent; Button Fern has fewer, flatter, more widely spaced leaflets on dark wiry stems.
- Most other ferns: Are feathery and finely divided; the Button Fern's simple round leaflets are an immediate giveaway.
- Pellaea falcata (sickle fern): A relative with longer, sickle-shaped leaflets rather than round ones.
Where You'll Find It
Grown indoors as a compact tabletop or terrarium fern, it tolerates slightly drier conditions than most ferns, reflecting its rocky native habitat in New Zealand. It prefers bright indirect light and a well-drained, slightly alkaline mix.
Quick ID Checklist
- Round, button-like leathery leaflets
- Dark, wiry reddish-brown stems
- Low, arching to trailing fronds 6-12 inches long
- Leaflets widely spaced, once-pinnate
- Spore bands along rolled-under leaflet margins
If you see a small fern with round, button-shaped leaflets strung along thin dark stems, you have a Button Fern.
Frequently asked questions
Why is it called a Button Fern?
Because its small, round, leathery leaflets resemble a row of buttons threaded along the wiry stem, which is unusual for a fern.
How do I tell it from a Lemon Button Fern?
Button Fern (Pellaea rotundifolia) has fewer, flatter, widely spaced round leaflets on dark wiry stems. The Lemon Button Fern has frillier, more crowded leaflets on green stems and gives off a faint lemon scent.
Does the Button Fern need a lot of water?
Less than most ferns. It comes from rocky New Zealand habitats and tolerates slightly drier, well-drained, slightly alkaline soil, though it still prefers even moisture and humidity.
Where are the spores on a Button Fern?
The spore-bearing sori form a continuous band along the rolled-under margins of each leaflet, partly hidden by the curled edge.