Topic: prickly shield fern
Is part of topic Common New Zealand ferns
Recognition: medium sized ground fern, with dark green, narrow, coarse textured, at least twice divided fronds, toothed frond segments, and prominent scales on the stems. In mainland New Zealand the scales have dark centres with a tan margin.
Distribution/ecology: from about Auckland southwards, occurring also in the Chatham Islands, New Zealand’s subantarctic islands, and Macquarie Island. In colder habitats, in forest, scrub, or grassland.
Relationships: Polystichum silvaticum is very similar but lacks indusia - the membranous structures that protect the sori (aggregations of the spore-producing sporangia). Like prickly shield fern, the other four indigenous Polystichum species all have shield-shaped (hence the genus’s common name) indusia protecting their round sori.
Polystichum is part of the Dryopteridaceae fern family. The other indigenous representatives are Lastreopsis (five species, with kidney-shaped indusia and hairs instead of scales), Rumohra (one species, which differs in being an epiphyte with a creeping rhizome), and Arachniodes (one species, only on the Kermadec Islands within the New Zealand region).