Nephrolepis cordifolia 'Duffii'

Species origin and cultivar background

Nephrolepis cordifolia has an exceptionally broad tropical and subtropical range, extending from São Tomé and south-western Cameroon through the western Indian Ocean, Asia and the Pacific. Depending on the site, it may grow on the ground, among rocks or on trees.

‘Duffii’ is the compact selection commonly sold as lemon button fern or button fern, recognised by its small rounded leaflets and short arching fronds. It also appears in horticulture as Nephrolepis duffii or “Duffy fern”.

Unlike Nephrolepis exaltata, this species can form small storage tubers on its underground runners. This helps explain why the two similar-looking ferns develop differently.

Moisture and airflow for healthy fronds

Renewal and propagation: Remove fully dead fronds at the base. Divide an established clump or separate young plants that have rooted along the creeping runners to preserve the cultivar.

Light and warmth: Nephrolepis ‘Duffii’ prefers bright filtered light. Steady indoor warmth suit steady frond production; protect the plant from cold draughts.

Moisture: Keep the root zone evenly moist without leaving it stagnant. Water when the surface just begins to lose moisture, wet the full root ball and let it drain.

Humidity, root care and watering: Humid air helps the short fronds expand fully, but the compact crown still needs ventilation. Use an airy fern mix that holds moisture, with coarse mineral material and leaf mould if needed to keep it open.

Troubleshooting Nephrolepis cordifolia 'Duffii': normal changes and damage

• Small underground nodules: Round scaly tubers attached to runners are a normal feature of Nephrolepis cordifolia Firm, organised tubers are storage organs, not insect eggs or root galls; retain them when dividing a healthy plant.
• Dots beneath leaflets: Orderly repeated sori on mature leaflets contain spores and do not move. Random cotton, attached shields, fine webbing or loose clusters do not follow that regular pattern and require a pest inspection.
• Crisp tips and leaflet drop: Evenly dry brown edges together with a light root ball indicate that the fern has dried too far. Rehydrate evenly, increase moisture checks and prevent the fine roots and tubers from cycling through complete dryness.
• Limp yellow fronds: Yellowing with wet, sour-smelling substrate or softness in the crown points to root or crown stress. Let excess water drain, clear dead material and replace collapsed substrate if it remains airless.
• Bleached patches: Pale dry areas confined to the light-facing side indicate scorch. Move the fern out of hot direct exposure while retaining bright filtered light; existing bleached tissue will not regain colour.
• Stippling, cotton or bumps: Mites produce pale stippling, bronzing and webbing; mealybugs leave cotton; scale appears as fixed bumps. Keep ‘Duffii’ apart, identify the pest and make sure treatment reaches the compact crown and lower frond surfaces.

Nephrolepis cordifolia ‘Duffii’ is non-toxic to cats and dogs

• This plant is non-toxic to cats and dogs.
• Its effects on people are unclear, so keep it away from young children who may chew it.
• Eating a large amount can still cause an upset stomach. Seek medical or veterinary advice if symptoms continue.

What does Nephrolepis cordifolia mean, and who first published it?

Greek nephros, kidney, and lepis, scale, form Nephrolepis and refer to the small kidney-shaped coverings over the spore-bearing patches. Cordifolia means heart-leaved.

Heinrich Wilhelm Schott established the genus Nephrolepis in 1834 in Genera Filicum (Vienna), plate 3.

Carl Linnaeus first described it as Polypodium cordifolium in 1753 in Species Plantarum, page 1089. Carl Bořivoj Presl later placed it in Nephrolepis as Nephrolepis cordifolia in 1836 in Tentamen Pteridographiae, page 79.