P. S. Green Royal Botanic Gardens, Kew, Richmond, Surrey, tw9 3AB, England



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divisionPTERIDOPHYTA***Jim: vol. 49

Vascular herbs, rarely arborescent, often rhizomatous, often with scales; true roots usually present (rhizoids in Psilotum). Leaves either bract-like or a frond which is circinate in bud (except in Psilotaceae, Lycopodiaceae, Selaginellaceae and Ophioglossaceae). Stipe usually lacking stipules (fleshy stipules in Marattiaceae, non-fleshy ones in Osmundaceae). Lamina broad, simple or variously pinnate, bearing sporangia. Sporangia usually in sori (often protected by an indusium) or grouped in synangia, or (in Psilotum) borne on the stems. Spores germinating to produce a prothallus which bears the male and female organs, producing, after fertilisation, the new sporophyte.

The ferns and fern allies are a large and ancient, worldwide division of land plants (very rarely, floating aquatics). They produce spores, usually in sori, which on germination develop into the sexual generation called the prothallus, which bears the male and female reproductive organs. Well known in the fossil state, especially from the Carboniferous Age, the group consists of four Classes, Psilopsida, Lycopsida, Sphenopsida and Filicopsida, all except the third occurring on Norfolk and Lord Howe Islands.


familyPSILOTACEAE

P.S.GreenRoyal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, England

Epiphytic, lithophytic or terrestrial; rhizomes dichotomously branched, bearing rhizoids. Aerial stems simple, forked once or dichotomously branched in upper part, bearing flattened 'leaves' or scale-like appendages. Synangia 2- or 3-lobed, homosporous.

A tropical or subtropical family containing only the following 2 living genera, and c. 12 species; both genera native on the Islands.

R.E.G.Pichi Sermolli, Tentatem Pteridophytorum genera in taxonomicum ordinem redigendi, Webbia 31: 313–512 (1977); R.A.White, D.W.Bierhorst, P.G.Gensel, D.R.Kaplan & W.H.Wagner Jr, Taxonomic and morphological relationships of the Psilotaceae, Brittonia 29: 1–68 (1977); D.L.Jones & S.C.Clemesha, Austral. Ferns & Fern Allies 2nd edn, 27–28 (1981); R.M.Tryon & A.F.Tryon, Ferns & Allied Pl. 782–787 (1982); D.L.Jones, Encycl. Ferns 44–47 (1987).

KEY TO GENERA



Synangia 3-chambered, subtended by a bifid scale-like sporophyll or leaf

1. PSILOTUM

Synangia 2-chambered, fused to a bifid leaf-like sporophyll

2. TMESIPTERIS



gen.
PSILOTACEAE
11. PSILOTUM

PsilotumSw.
J. Bot. (Schrader) 1800(2): 109(1801)
from the Greek psilos (naked or bare), in allusion to the naked synangia

Type: P. triquetrum Sw., nom. illeg. = P. nudum (L.) P.Beauv.

Terrestrial, lithophytic or epiphytic plants, rhizomatous, creeping; rhizome bearing rhizoids, not true roots. Stems erect or pendulous, often tufted, dichotomously branched, bearing scale-like sporophylls ('leaves'). Fertile sporophylls bract-like, bifid, subtending a ±sessile 3-lobed synangium.

A genus of 2 species distributed throughout the tropics and subtropics. Together with Tmesipteris (below), structurally the most primitive living genera of vascular plants. One species is native to both Islands.

G.Bentham, Lycopodiaceae, Psilotum, Fl. Austral. 7: 681–682 (1878).


1
Psilotum
nudum(L.) P.Beauv.
Prodr. Aetheogam. 112(1805)


Lycopodium nudum L., Sp. Pl. 2: 1100 (1753); Psilotum triquetrum Sw., J. Bot. (Schrader) 1800(2): 109 (1801), nom. illeg.T: 'in Indiis'; lecto: LINN 1257.1, fide G.R.Proctor in R.A.Howard, Fl. Lesser Antilles 2: 16 (1977); IDC microfiche 177/2.734/21. The epithet comes from the Latin nudus (naked), in reference to the synangia.

Illustrations: D.L.Jones & S.C.Clemesha, Austral. Ferns & Fern Allies 2nd edn, 28 (1981); D.L.Jones, Encycl. Ferns 45, 49 (1987); P.G.Wilson in G.J.Harden, Fl. New South Wales 1: 3, t. 1 (1990).

Tough herb. Stems erect, 15–50 cm tall, 2–4 mm thick, simple basally, repeatedly dichotomously branched in the upper part; branches 3-angled. Scales scattered, ovate-subulate, 2–3 mm long; fertile leaves 2-lobed, subulate, c. 2 mm long, subtending ±sessile synangia on uppermost branches; synangia ±globular, 3-celled, c. 2 mm diam., yellow when mature.

Skeleton Forkfern.

Norfolk Is., Lord Howe Is. On Norfolk Is. occasional to common in the National Park, occasional elsewhere; common throughout Lord Howe Is. Also in Australia and the North Is. of New Zealand, and widespread throughout the tropics and subtropics.

N.Is.: Mt Pitt Reserve, M.Lazarides 8076 (CANB); s. loc., A.Cunningham 61 (K). L.H.Is.: Transit Hill, P.S.Green 1637 (A, K); near Lovers Bay, R.D.Hoogland 8725 (CANB, NSW).


gen.
PSILOTACEAE
22. TMESIPTERIS

TmesipterisBernh.
J. Bot. (Schrader) 1800(2): 131(1801)
from the Greek tmesis (cutting or incision) and pteris (fern), in allusion to the sporophyll being cut in two in these fern allies

Type: T. tannensis (Spreng.) Bernh.

Rhizomatous herbs. Aerial branches simple or forked once (elsewhere, repeatedly forked), bearing flattened appendages ('leaves') with a midrib. Synangia of paired sporangia fused to these leaf-like structures.

A genus of c. 10 species, mostly from eastern Australia and New Zealand, but also from Mindanao, Celebes, Papua New Guinea, Solomon Is., Vanuatu, New Caledonia, Fiji, Samoa, Tahiti and the Marquesas. Two native species, 1 on each of the Islands.

Sometimes classified in its own family, the Tmesipteridaceae.

G.Bentham, Lycopodiaceae, Tmesipteris, Fl. Austral. 7: 680–681 (1878); M.M.J. van Balgooy, Blumea Suppl. 5: 274–275 (1966); R.J.Chinnock, The New Zealand species of Tmesipteris (Psilotaceae), New Zealand J. Bot. 13: 743–768 (1975).

Synangia ±globose, blunt, 3.5–4 mm long, 1.75–2 mm broad; leaf-like appendages acute, apiculate (N.Is.)

1. T. norfolkensis

Synangia somewhat elongated, ±pointed, 5.5–6 mm long, 1.25–1.5 mm broad; leaf-like appendages subtruncate, prominently apiculate (L.H.Is.)

2. T. truncata



1
Tmesipteris
norfolkensisP.S.Green
J. Arnold Arbor. 67: 109(1986)


T: Norfolk Island, 1804–1805, F.L.Bauer; holo: W.

Tmesipteris forsteri Endl., Prodr. Fl. Norfolk. 6 (1833), nom. illeg.; Psilotum forsteri (Endl.) Endl., Iconogr. Gen. Pl. ix, t. 85 (1838), nom. illeg.T: Norfolk Island, 1804–1805, F.L.Bauer; holo: W.

[Tmesipteris tannensis auct. non (Spreng.) Bernh.: J.H.Maiden, Proc. Linn. Soc. New South Wales 28: 740 (1904); R.M.Laing, Trans. & Proc. New Zealand Inst. 47: 15 (1915); C.F.Reed, Bol. Soc. Brot. ser. 2, 40: 84 (1966)]

[Tmesipteris truncata auct. non (R.Br.) Desv.: C.F.Reed, op. cit. 85, p.p.]

[Tmesipteris billardieri auct. non Endl.: M.D.Tindale in N.C.W.Beadle et al., Fl. Sydney Region 3rd edn, 40 (1982), p.p.]


Illustration: S.F.L.Endlicher, Iconogr. Gen. Pl. t. 85 (1835).

Pendulous epiphyte on trunks of tree ferns. Branches 10–25 cm long, of limited growth. Leaf-like appendages slightly sigmoid, 10–20 mm long, 3–5 mm broad, acute, apiculate. Synangia ±globose, 3.5–4 mm long, 1.75–2 mm broad, blunt.

Hanging Forkfern.

Fig. 101A.v*****_f*****.jpg

Norfolk Is. Endemic.

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