Class
Subclass
Order
Family
Classification
Subordinate Taxa
Nomenclature
Scientific Name:
Polystichum Roth, Tent. Fl. Germ. 3, 31 (1799), nom. cons.
Synonymy:
- = Hypopeltis Michx., Fl. Bor.-Amer. [Michaux] 2, 226 (1803)
Type Taxon:
Polystichum lonchitis (L.) Roth.
Etymology:
Vernacular Name(s):
shield fern
Description
Terrestrial ferns, evergreen or occasionally marcescent. Rhizomes erect, scaly. Rhizome scales non-clathrate, ovate or narrowly ovate, margins entire or fimbriate, attached at base, concolorous or bicolorous, pale brown to black-brown. Fronds monomorphic, sometimes bulbiferous. Stipes and rachises scaly, adaxially sulcate. Laminae 1–3-pinnate (NZ), or 4-pinnnate (not NZ), herbaceous or coriaceous, scaly. Veins free. Sori round, borne on abaxial surface, away from the margin, in 1 row either side of midrib; indusia round, peltate. Spores monolete; perispores tuberculate or cristate, often reticulate or fenestrate, rarely minutely echinate on the surface.
Taxonomy
A genus of c. 500 species included in the subfamily Dryopteridoideae (PPG 1 2016).
Polystichum is considered to be monophyletic (Le Péchon et al. 2016) and sister to Cyrtomium. The polystichoid ferns are sister to the dryopteroid ferns, the latter comprising Arachniodes and Dryopteris (Liu et al. 2016).
Allan (1961) recognised four indigenous species in New Zealand – P. cystostegia, P. richardii, P. sylvaticum (as silvaticum) and P. vestitum. However, Perrie et al. (2003a) showed that plants previously referred to P. richardii comprised an allo-octoploid complex with two tetraploid species, P. oculatum and P. wawranum, and an octoploid species, P. neozelandicum.
Two naturalised species, P. proliferum and P. setiferum, and one casual species, P. lentum, were recorded by Brownsey (1981). A second casual species, P. polyblepharum, was reported by Heenan et al. (2004).
Key
| 1 | Fronds bearing bulbils | 2 |
| Fronds lacking bulbils | 4 | |
| 2 | Fronds with numerous bulbils, borne along the rachis at junctions with the primary pinnae | setiferum |
| Fronds with one or a few bulbils, borne near the apex of the rachis | 3 | |
| 3 | Proximal primary pinnae bearing several stalked secondary pinnae | proliferum |
| Proximal primary pinnae sometimes divided to the costa, but never bearing more than one stalked secondary pinna | lentum | |
| 4 | Indusia with conspicuous black centres, or, if only tiny dark centres, scales at stipe/rachis junction with colourless, fimbriate margins at their bases | 5 |
| Indusia uniformly pale brown, or absent; scales at stipe/rachis junction with entire or ciliate margins | 7 | |
| 5 | Scales at stipe/rachis junction appearing hair-like to the naked eye (<130 μm wide); indusia often lacking an obvious dark centre | wawranum |
| Scales at stipe/rachis junction obviously scale-like to the naked eye (>130 μm wide); indusia always with an obvious dark centre | 6 | |
| 6 | Scales at stipe/rachis junction ovate or broadly ovate, >750 μm wide (and usually >1000 μm wide); spores 36–48 μm long, 27–36 μm wide | oculatum |
| Scales at stipe/rachis junction ovate or narrowly ovate, <650 μm wide; spores 46–58 μm long, 36–45 μm wide | neozelandicum | |
| 7 | Scales at stipe/rachis junction concolorous | 8 |
| Scales at stipe/rachis junction bicolorous, with shiny dark centres and pale margins | 9 | |
| 8 | Stipe and rachis scales entire; indusia markedly convex; plants of alpine regions | cystostegia |
| Stipe and rachis scales irregularly toothed; indusia ± flat; naturalised plants of urban areas | polyblepharum | |
| 9 | Indusia absent; costae of primary pinnae with narrow wings | sylvaticum |
| Indusia present; costae of primary pinnae lacking wings | vestitum |
Recognition
In New Zealand, species of Polystichum are recognised by their terrestrial habit, erect rhizomes, 1–3-pinnate fronds, abundant and sometimes bicolorous scales, and round sori protected by round indusia. Three naturalised species are bulbiferous, unlike any other species of Dryopteridaceae in New Zealand. The spores are tuberculate or cristate, often with complex fenestration and reticulation (Large & Braggins 1991).
Distribution
Polystichum is widespread in north and south temperate regions, and in montane to alpine regions of the warm temperate and tropical zones. The centres of diversity are in southern Asia, and in Central and South America (Zhang & Barrington 2013); 208 species in China (Zhang & Barrington 2013), 22 in Africa and Indian Ocean islands (Roux 2009), four in Australia (Jones 1998), perhaps five in the south Pacific, and three in Hawai‘i (Palmer 2003). Ten species in New Zealand; five endemic, one indigenous, and four naturalised or casual.
Biostatus
Indigenous (Non-endemic)
| Category | Number |
|---|---|
| Indigenous (Endemic) | 5 |
| Indigenous (Non-endemic) | 1 |
| Exotic: Fully Naturalised | 2 |
| Exotic: Casual | 2 |
| Total | 10 |
Hybridisation
Hybridisation is common amongst the indigenous species of Polystichum in New Zealand. Seven different combinations were recorded by Perrie et al. (2003a, 2003b). Plants of hybrid origin can be identified by their abnormally formed spores, but determining parentage depends on morphology and field observations of what species were growing in the immediate vicinity of the putative hybrid.
Cytology
The base chromosome number in Polystichum is x = 41 (Kramer 1990).
Bibliography
Brownsey, P.J. 1981: Checklist of pteridophytes naturalised in New Zealand. New Zealand Journal of Botany 19: 9–11.
Brownsey, P.J.; Perrie, L.R. 2021: Dryopteridaceae. In: Breitwieser, I. (ed.) Flora of New Zealand — Ferns and Lycophytes. Fascicle 31. Manaaki Whenua Press, Lincoln.
Heenan, P.B.; de Lange, P.J.; Cameron, E.K.; Ogle, C.C.; Champion, P.D. 2004: Checklist of dicotyledons, gymnosperms, and pteridophytes naturalised or casual in New Zealand: additional records 2001–2003. New Zealand Journal of Botany 42: 797–814.
Jones, D.L. 1998: Dryopteridaceae. In: Flora of Australia. Vol. 48. 393–418.
Kramer, K.U. 1990: Dryopteridaceae. In: Kramer, K.U.; Green, P.S. Pteridophytes and gymnosperms. Vol. 1. In: Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Springer-Verlag, Berlin.
Kramer, K.U.; Green, P.S. 1990: Pteridophytes and gymnosperms. Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Vol. 1. Springer-Verlag, Berlin.
Large, M.F.; Braggins, J.E. 1991: Spore atlas of New Zealand ferns and fern allies. SIR Publishing, Wellington.
Le Péchon, T.; He, H.; Zhang, L.; Zhou, X-M.; Gao, X-F.; Zhang, L-B. 2016: Using a multilocus phylogeny to test morphology-based classifications of Polystichum (Dryopteridaceae), one of the largest fern genera. BioMed Central Evolutionary Biology 16: 55.
Liu, H.-M.; Zhang, X.-C.; Wang, M.-P.; Shang, H.; Zhou, S.-L.; Yan, Y.-H.; Wei, X.-P.; Xu, W.-B.; Schneider, H. 2016: Phylogenetic placement of the enigmatic fern genus Trichoneuron informs on the infra-familial relationships of Dryopteridaceae. Plant Systematics and Evolution 302: 319–322.
Michaux, A. 1803: Flora Boreali-Americana. Vol. 2. Crapelet, Paris.
Palmer, D.D. 2003: Hawai‘i’s ferns and fern allies. University of Hawai‘i Press, Honolulu.
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(2): 189–215.
Perrie, L.R.; Brownsey, P.J.; Lockhart, P.J.; Large, M.F. 2003b: Morphological and genetic diversity in the New Zealand fern Polystichum vestitum (Dryopteridaceae), with special reference to the Chatham Islands. New Zealand Journal of Botany 41(4): 581–602.
PPG 1 2016: A community-derived classification for extant lycophytes. Journal of Systematics and Evolution 54(6): 563–603.
Roth, A.W. 1799: Tentamen Florae Germanicae. Vol. 3. Gleditsch, Leipzig.
Roux, J.P. 2009: Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighbouring islands. Strelitzia 23: 1–296.
Zhang, L.; Barrington, D.S. 2013: Cyrtomium. In: Zhengyi, W.; Raven, P.H.; Deyuan, H. (ed.) Flora of China. Lycopodiaceae through Polypodiaceae. Vol. 2–3. Science Press, Beijing.
