Classification
Class
Polypodiopsida
Subclass
Ophioglossidae
Order
Psilotales Prantl
Family
Psilotaceae J.W.Griff. & Henfr.
Genus
Psilotum Sw.
 Nomenclature
Scientific Name:
Psilotum nudum (L.) P.Beauv., Prodr. Aethéogam. 106, 112 (1805)
Synonymy:
  • ≡ Lycopodium nudum L., Sp. Pl. 1100 (1753)
Lectotype (selected by Proctor 1977): “Habitat in Indiis”, Herb. Linn. No. 1257.1, LINN! (photo WELT E475/5)
  • = Psilotum triquetrum Sw., J. Bot. (Schrader) 1800(2): 109 (1801)
Holotype: Martinique, B, Herb. Willdenow
  • = Bernhardia novae-hollandiae Müll.Berol., Bot. Zeitung (Berlin) 14: 237 (1856)
Lectotype (selected by Brownsey & Perrie 2014): Port Jackson [Sydney, New South Wales], R. Brown Iter. Austral. 120, K! (photo WELT E472/7).
  • = Psilotum heterocarpum Colenso, Trans. & Proc. New Zealand Inst. 20: 237 (1888)
Lectotype (selected by Brownsey & Perrie 2014): New Zealand, Wairakei, Taupo, C.J. Norton s.n., 1887, Herb. Colenso, WELT P003168!
  • = Psilotum novae-zelandiae Gand., Bull. Soc. Bot. France 66: 306 (1919)
Holotype: Nova Zelandia [New Zealand], Aston, LY
Etymology:
From the Latin nudum (naked), a reference to the apparent lack of leaves.
 Description

Terrestrial, rupestral or occasionally epiphytic ferns. Aerial stems erect, 40–725 mm long, 13–290 mm wide. Unbranched portion of stem 20–420 mm long, 0.5–3 mm in diameter, green or yellow-green; distal portion dichotomously branched 3-many times, strongly ribbed, green, stiff or sometimes flaccid in shaded habitats, glabrous. Sterile leaves 1–3 mm long, scale-like, confined to ribs, spirally arranged, pale yellow, lacking veins. Synangia 1–1.5 mm long, 1.5–3 mm wide, yellow, unprotected, projecting slightly from sides of stems.

 Recognition

This species is easily recognised by its twiggy, upright stems, scale-like leaves, and trilobed synangia borne adaxially on bifid sporophylls.

 Distribution

North Island: Northland, Auckland, Volcanic Plateau.

Kermadec Islands.

Altitudinal range: 0–450 m.

Psilotum nudum occurs on Raoul Island and in coastal areas of Northland, but is uncommon on the mainland in the Auckland region, except around Auckland City, on Rangitoto Island and in eastern Coromandel. It has been collected on offshore islands from the Poor Knights Islands to Whale Island in the eastern Bay of Plenty, and has been reported (without voucher) from Urupukapuka Island in the Bay of Islands (Young 2009). On the west coast it extends to Kāwhia Harbour, and it is common on thermally heated soils of the Rotorua/Taupō region as far south as Tokaanu. It occurs from near sea level to about 150 m in most of its range, but grows up to 400 m on Raoul Island and 450 m on the cliffs around Lake Rotomahana.

Also widespread in tropical and subtropical regions including Australia (Western Australia, Northern Territory, Queensland, NSW, Victoria) and most islands of the Pacific.

Psilotum nudum distribution map based on databased records at AK, CHR and WELT. Image: K. Boardman © Landcare Research 2014 CC BY 3.0 NZ
Psilotum nudum distribution map based on databased records at AK, CHR and WELT. Image: K. Boardman © Landcare Research 2014 CC BY 3.0 NZ
 Habitat

On Raoul Island, Psilotum nudum is common under dry forest in the crater area, usually on the forest floor, but also on rotten wood or epiphytic on Metrosideros. In Northland and on the Hauraki Gulf and Coromandel islands it occurs under pōhutukawa forest on rocky or sandy soil, on open coastal cliffs and banks, in rock crevices and amongst scoria. Very occasionally it occurs as an epiphyte on pōhutukawa or kōwhai. In Auckland City it is found on walls, in rocky areas, amongst scoria and in planted areas, where it has been accidentally introduced. Around Kāwhia Harbour it grows on limestone outcrops. However, it is most abundant on thermally heated ground in the Rotorua/Taupō area on cliffs, rocky ground, in crevices, around steam vents and under light kānuka and mānuka scrub.

 Biostatus
Indigenous (Non-endemic)
 Cytology

n = 104 (Brownsey & Lovis 1987).

 Notes

The gametophytes of Psilotum nudum are unusual amongst ferns in being subterranean, non-green, mycorrhizal, cylindrical and frequently branched (Holloway 1939; Bierhorst 1954). They are similar to those of Tmesipteris in this regard.

 Images
Psilotum nudum: dichotomously branched aerial stem bearing trilobed synangia on adaxial surface of tiny bifid scales. Image: L.R. Perrie © Te Papa 2006 CC BY-NC 3.0 NZ
Psilotum nudum: dichotomously branched aerial stem bearing trilobed synangia on adaxial surface of tiny bifid scales. Image: L.R. Perrie © Te Papa 2006 CC BY-NC 3.0 NZ
 Bibliography
Bierhorst, D.W. 1954: The gametangia and embryo of Psilotum nudum. American Journal of Botany 41: 274–281.
Brownsey, P.J.; Given, D.R.; Lovis, J.D. 1985: A revised classification of New Zealand pteridophytes with a synonymic checklist of species. New Zealand Journal of Botany 23(3): 431–489.
Brownsey, P.J.; Lovis, J.D. 1987: Chromosome numbers for the New Zealand species of Psilotum and Tmesipteris, and the phylogenetic relationships of the Psilotales. New Zealand Journal of Botany 25(3): 439–454.
Brownsey, P.J.; Perrie, L.R. 2014: Taxonomic notes on the New Zealand flora: types in the fern family Psilotaceae. New Zealand Journal of Botany 52(2): 267–269.
Brownsey, P.J.; Perrie, L.R. 2015: Psilotaceae. In: Breitwieser, I; Heenan, P.B.; Wilton, A.D. (ed.) Flora of New Zealand — Ferns and Lycophytes. Fascicle 9. Manaaki Whenua Press, Lincoln.
Brownsey, P.J.; Smith-Dodsworth, J.C. 2000: New Zealand ferns and allied plants. Edition 2. David Bateman, Auckland.
Colenso, W. 1888: On new indigenous cryptogams of the orders Lycopodiaceae, Musci and Hepaticeae. Transactions and Proceedings of the New Zealand Institute 20: 234–254.
de Lange, P.J.; Rolfe, J.R.; Barkla J.W.; Courtney, S.P.; Champion, P.D.; Perrie, L.R.; Beadel, S.N.; Ford, K.A.; Breitwieser, I.; Schönberger, I.; Hindmarsh-Walls, R.; Heenan, P.B.; Ladley, K. 2018: Conservation status of New Zealand indigenous vascular plants, 2017. New Zealand Threat Classification Series. No. 22. [Not Threatened]
de Lange, P.J.; Rolfe, J.R.; Champion, P.D.; Courtney, S.P.; Heenan, P.B.; Barkla, J.W.; Cameron, E.K.; Norton, D.A.; Hitchmough, R.A. 2013: Conservation status of New Zealand indigenous vascular plants, 2012. New Zealand Threat Classification Series 3. Department of Conservation, Wellington. [Not Threatened]
Gandoger, M. 1919: Sertum plantarum novarum. Pars secunda. Bulletin de la Société Botanique de France 66: 286–307.
Holloway, J.E. 1939: The gametophyte, embryo, and young rhizome of Psilotum triquetrum Swartz. Annals of Botany, London (new series) 3: 313–336. [as Psilotum triquetrum Sw.]
Linnaeus, C. 1753: Species Plantarum. Impensis Laurentii Salvii, Stockholm.
Müller, K. 1856: Monographische kritik der Lycopodiaceen-gattung Psilotum Sw. Botanische Zeitung (Berlin) 14: 233–243.
Palisot de Beauvois, A.M.F.J. 1805: Prodrome des cinquième et sixième familles de l'Aethéogamie. Les mousses. Les lycopodes. Fournier, Paris.
Proctor, G.R. 1977: Pteridophyta. In: Howard, R.A. Flora of the Lesser Antilles. Arnold Arboretum, Harvard University, Jamaica Plain, Mass.
Swartz, O.P. 1801: Genera et species filicum ordine systematico redactarum. Journal für die Botanik (Schrader) 1800(2): 1–120.
Young, M. 2009: Botany of some of the islands in the eastern Bay of Islands, Northern New Zealand: an update. Auckland Botanical Society Journal 64: 88–97.