Soft Shield-fern
The genus name Polystichum derives from Greek meaning “many rows”, referring to the arrangement of the sori, while the specific epithet setiferum means “bearing bristles”, describing the fine bristle-tipped teeth along the pinnules.
Identification
One of two common shield-ferns found in British woodlands, though generally the scarcer of the pair in North East England, Soft Shield-fern is a graceful species of cool, humid and sheltered habitats. Its finely divided, soft-textured fronds give it a delicate and distinctly feathery appearance, quite unlike the stiffer form of Hard Shield-fern.
Owing to its ornamental qualities, the species has long been popular in cultivation and has produced a remarkable range of garden forms and cultivars, some of which may occasionally persist or escape into the wild.
Fronds: a graceful semi-evergreen fern forming loose shuttlecock-like tufts of soft-textured fronds. Fronds are bright to mid-green, narrowly lanceolate and typically 30–120 cm long, with a lax, arching habit. They are bipinnate, occasionally tripinnate toward the base, and much softer and more finely divided than those of Hard Shield-fern.
Pinnae and pinnules: Pinnae are arranged opposite to sub-opposite along the rachis. Pinnules are short-stalked, rounded to oblong and finely serrated, each tooth terminating in a fine bristle-like point. Those nearest rachis are stalked into an obtuse-angled base.
Stipe: Comparatively long, usually around one-fifth to one-third of the frond length. The stipe and lower rachis are clothed with pale to orange-brown scales.
Sori: Rounded sori arranged in two rows on the undersides of the pinnules. Each sorus is covered by a circular indusium.
Similar Species
Soft Shield-fern is most likely to be confused with Hard Shield-fern Polystichum aculeatum, but differs in its softer, more feathery fronds, longer stipe and stalked pinnules. The two hybridise fairly frequently, giving rise to Polystichum x bicknellii.
| Feature | Polystichum aculeatum | Polystichum setiferum | Polystichum × bicknellii |
| Frond texture | Hard, stiff and leathery | Soft-textured, delicate | Intermediate, but usually firm and leathery |
| Stipe length | Short, rarely more than one-fifth of frond length | Long, often around one-third of frond length | Long, resembling P. setiferum |
| Pinnules nearest rachis | Sessile and decurrent from an acute-angled base | Stalked with an obtuse-angled base | Mixture of both; at least some stalked at roughly 90° |
| Overall appearance | Glossy, rigid and strongly architectural | Graceful, feathery and lax | Intermediate between the two parents |
Habitat
Soft Shield-fern is a characteristic species of humid, shaded woodland and other sheltered habitats with consistently moist conditions. It is most frequent on acidic to neutral soils, particularly in ancient woodland, wooded stream valleys, hedge banks and rocky slopes, where it often grows among mosses, boulders and tree roots. The species favours high humidity and protection from exposure, thriving in mild, oceanic climates and areas with reliable rainfall.
