Rustyback Fern
Asplenium ceterach
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Turn a frond over and the underside is covered in rust-coloured scales.
A small, distinctive evergreen fern with thick, leathery, deeply lobed fronds, dark green above and — the giveaway — densely covered beneath in overlapping silvery scales that age to rust-brown. Rustyback grows in the mortar of old walls, on limestone and in rock crevices, and is local rather than common around Dumfries.
Behaviour
It is remarkably drought-tolerant for a fern: in dry weather the fronds curl inward and shrivel, exposing the rusty scales and appearing dead, then unroll and green up again within hours of rain. The scales reduce water loss and reflect sunlight. It needs lime, so it is largely confined to mortared walls and base-rich rock in this otherwise acidic region.
When to see it
Quick facts
- Family
- Spleenworts (Aspleniaceae)
- Frond
- 5–20 cm, scaly beneath
Photo by Joanbanjo, CC BY-SA 4.0, via Wikimedia Commons