Polystichum neozelandicum subsp. zerophyllum
Common name
shield fern
Synonyms
Aspidium zerophyllum Colenso, Polystichum richardii (Hook.) J.Sm.
Family
Dryopteridaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Ferns
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
POLNSZ
Chromosome number
2n = c.328
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | Not Threatened
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
Distribution
Endemic. New Zealand: North, South, Stewart and Chatham Islands, In the North Island ranging from Taupo and the South Bay of Plenty southwards (but extent of overlap with P. neozelandicum subsp. neozelandicum not clear).
Habitat
Coastal to montane. Common fern of forested hillsides and banks, coastal cliff faces (under scrub), usually in well-lit conditions. It has also extended its range into urban situations where it sometimes a feature of roadside banks and cuttings.
Features
Rhizomes short, erect. Stipes 100–420 mm long. Stipes and rachises moderately to densely scaly. Scales obviously scale-like to the naked-eye; usually acicular-lanceolate; usually widest in the basal third of length; those from the stipe-rachis junction usually 135–570 µm wide at mid length; mid to dark brown, often appearing black to the naked eye; apex tapering; margins almost always with projections which usually taper to cilia-like apices; underlain by smaller scales, including ‘arachnioid’ scales with fimbriate bases. Lamina 175–525 × 90–220 mm, bipinnate with the basal primary pinnae of some large fronds becoming tripinnate; usually forest green with primary and secondary costae blackish blue. Primary pinnae in 11–25 pairs, the longest 45–120 × 5–38 mm. Secondary pinnae stalked and free towards the base of primary pinnae, becoming sessile and adnate towards the apex of primary pinnae; with sharply pointed apices and usually additional marginal teeth and/or crenulations. Sori round. Indusia peltate, ± flat, ± round, with entire, although often undulate and/or scalloped, margins; persistent; central dark area moderately sized (5–30% surface area).
Similar taxa
According to Perrie (2003) the distributions of P. neozelandicum subsp. neozelandicum and subsp. zerophyllum do not overlap. Both subspecies are primarily distinguished by the size of the dark pigmented centre of the indusia, which in subsp. neozelandicum is usually larger in the former (Perrie 2003) viz, 15-60% surface area, and usually > c. 30% in subsp. neozelandicum and 5-30% surface area in subsp. zerophyllum. However, on the Chatham Islands at least, both subspecies are sympatric (de Lange et al. 2011). Some botanists have reported that the distinctions between the two subspecies overlaps and that it may be better to regard P. neozelandicum as just the one species (C. Ecroyd pers. comm.). Polystichum oculatum is superficially similar. It is distinguished by its broad, often pentagonal scales, widely inserted and relatively broad pinnae, indusia with obvious dark centres, and relatively small spores. Polystichum wawranum is also somewhat similar. However it is distinguished by its hair-like scales, closely inserted and relatively long narrow pinnae, indusia mostly lacking obvious dark centres, and relatively small spores. Polystichum wawranum is often sympatric with both subspecies of P. neozelandicum.
Flowering
Not Applicable - Spore Producing
Flower colours
No flowers
Fruiting
Not Applicable - Spore Producing
Propagation technique
Easily grown from fresh spores and transplants. However, often slow to establish. Does best in a shaded site planted within a deep, free draining humus-enriched fertile soil. Polystichum neozelandicum (either subspecies) is also an excellent pot plant.
Etymology
polystichum: Many rows (of sori); from the Greek polus and stikhos; parallel rows of spore cases
Where To Buy
Occasionally available, though often sold as Polystichum richardii.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (13 November 2012). Description adapted from Perrie et al. (2003).
References and further reading
de Lange, P.J.; Heenan, P.B.; Rolfe, J.R. 2011: Checklist of vascular plants recorded from the Chatham Island Islands. Department of Conservation, Wellington. 57pp.
Perrie, L.R.; Brownsey, P.J.; Lockhart, P.J.; Large, M.F. 2003A: Evidence for an allopolyploid complex in New Zealand Polystichum (Dryopteridaceae). New Zealand Journal of Botany 41: 189-215
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Polystichum neozelandicum subsp. zerophyllum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/polystichum-neozelandicum-subsp-zerophyllum/ (Date website was queried)