It often grows in exposed positions and is then somewhat stunted and gnarled.
L.H.Is.: top of Mt Gower, P.S.Green 1591 (K); summit plateau of Mt Gower, J.Pickard 2644, 3573 & 3595 (NSW); loc. id., A.N.Rodd 1367 (NSW).
This species is said to spread and reproduce by means of stolons.
robustaHolttum Blumea 12: 265(1964)
Alsophila robusta C.Moore ex Maiden, Proc. Linn. Soc. New South Wales 23: 144 (1898), non de Vriese (1852); Sphaeropteris robusta (Holttum) R.M.Tryon, Contr. Gray Herb. 200: 24 (1970).T: Lord Howe Island, C.Moore 1; holo: K. Named in allusion to its robust habit.
Alsophila australis var. nigrescens Benth., Fl. Austral. 7: 711 (1878).T: Lord Howe Island, C.Moore; holo: ?MEL n.v.
Trunk to 5 m tall, with roundish scars; stipe bases variably persistent with lower parts of trunk often clear. Fronds: stipe c. 1 m long, rough, ±glaucous, with basal scales 2–4 cm long, whitish, with dark brown, setiferous margins; costae (and to a lesser extent costules) with pale scales of mixed sizes with setiferous margins below, and with fine pale antrorse setiferous hairs on veins above; lamina tripinnate; primary pinnae to 50 cm long; pinna rachis with numerous short warty excrescences and small scurfy scales, occasionally with white caducous scales; secondary pinnae 7–11 cm long, 1.2–2 cm broad; largest pinnules 18–20 pairs, 5–6 mm long, 2.5–3 mm broad, free. Sori without indusia, with paraphyses around the base.
Lord Howe Is. Endemic; widespread, but rarer than the other species, scattered in the southern mountainous areas at low to medium elevations.
L.H.Is.: Boat Harbour track, J.Pickard 2649 (K, NSW); Rocky Run, J.Pickard 3424 (NSW); Dinner Run, P.S.Green 2341 (K); N side of Mt Lidgbird, A.C.Beauglehole 5365 (MEL).
T: Norfolk Island, 1804–1805, F.L.Bauer; holo: W. Named after Robert Brown (1773–1858), naturalist on Lieutenant M.Flinders' voyage of exploration around Australia in the Investigator.
Alsophila excelsa R.Br. ex Endl., Prodr. Fl. Norfolk. 16 (1833), non Cyathea excelsa Sw.; Sphaeropteris excelsa (R.Br. ex Endl.) R.M.Tryon, Contr. Gray Herb. 200: 24 (1970).T: as for Cyathea brownii.
Alsophila robusta var. norfolkiana R.M.Laing, Trans. & Proc. New Zealand Inst. 47: 9 (1915).T: Norfolk Is., R.M.Laing; holo: CHR.
Illustrations: W.J.Hooker, Gen. Fil. t. 9 (1842); W.J.Hooker, Sp. Fil. 1: t. 18A (1844); D.L.Jones, Encycl. Ferns: 25 (1987).
Trunk usually to 5 m, rarely to 18 m tall, smooth, with stipe base scars. Fronds: stipe 30–50 cm long, finely warty; basal scales narrow, 2–4 cm long, lightish brown, caducous; costae and costules below with dense felted hairs and small narrow scales with marginal hairs; costae above with shortish crisped antrorse hairs, glabrous on upper surface of veins; lamina tripinnate; primary pinnae to 60 cm long with apex long-pointed; pinna rachis finely warty with caducous, fine, ±felted hairs; secondary pinnae 7–13 cm long, 1.5–2.2 cm broad; largest pinnules 16–18 pairs, 8–15 mm long, 2–4 mm broad, free, shallowly crenate, acuminate; fertile pinnules with margin recurved over sori. Sori without indusium, with paraphyses.
Norfolk Tree Fern, Farn.
Norfolk Is. Endemic; common, occurring at all elevations.
N.Is.: Palm Glen, R.D.Hoogland 11358 (K, NSW); top of Mount Bates, P.S.Green, P.Ralston & O.Evans 1419 (K); Now-Now Valley, W.Laing (CHR).
Records of individuals with trunks to 24 m tall have been reported in the past.
Culcita dubia (R.Br.) Maxon was, under the name Davallia dubia R.Br., recorded from Lord Howe Is. by G.Bentham (Fl. Austral. 7: 178, 1878), citing a Moore & Fullagar specimen, but no such collection is represented in the herbarium at Kew, where Bentham worked. There is, however, a specimen of this species labelled: 'Lord Howe's Island, Herb. Macleay, received 5/73' in Baker's hand, but there has been no other record and, without such confirmation, it is best to treat this specimen as having been mislabelled.
Terrestrial ferns. Rhizome erect or creeping; scales with marginal, also often superficial, unicellular hairs. Fronds pinnate to usually bipinnatifid or sometimes tripinnatifid, with a transparent membrane in the sinus between pinna lobes; hairs acicular, unicellular on upper surface, sometimes with glandular hairs beneath; veins free or those from adjacent costules joining to produce an excurrent vein ending in a sinus. Sori round, indusiate, rarely naked; indusia kidney-shaped.
A worldwide family of 15 or more genera and c. 900 species; 2 native genera on Norfolk Is., 1 of which also occurs on Lord Howe Is.
The family was misinterpreted in the past and is currently under revision. An earlier belief in an affinity with Dryopteris is now discounted.
G.Bentham, Filices, Aspidium, Fl. Austral. 7: 756 (1878); R.E.Holttum, The family Thelypteridaceae in the Old World, J. Linn. Soc., Bot. 67: Suppl. 173–189 (1973); R.E.Holttum, The family Thelypteridaceae in the Pacific and Australia, Allertonia 1: 169–223 (1977).
KEY TO GENERA
Fronds pinnate to bipinnatifid; pinnules not as below
ChristellaH.Lév. Fl. Kouy-Tchéou 472(1915) named after K.H.H.Christ (1833–1933), Swiss pteridologist
Type: C. parasitica (L.) H.Lév.
Terrestrial ferns. Rhizomes erect or creeping; scales narrow, setiferous. Fronds pinnate, with basal veins of pinna segments usually anastomosing; hairs on both surfaces acicular, with short, capitate hairs often present, and the lower surface sometimes with thick, glandular hairs. Sori ±circular, indusiate.
A genus of c. 50 species, found throughout the tropics and subtropics, especially in the Old World; 1 species native to Norfolk Is.; 1 species native to both Islands.
R.E.Holttum, The genus Christella H.Lév., Sect. Christella, Kew Bull. 31: 293–339 (1976).
Lower pinnae in several pairs gradually reduced in length; rhizome ±tufted or very shortly creeping; veins beneath without orange glandular hairs (N.Is., L.H.Is.)
1. C. dentata
Lower 1 or 2 pairs of pinnae ±abruptly reduced in length; rhizome distinctly creeping; veins beneath with orange glandular hairs (N.Is.)
Polypodium dentatum Forssk., Fl. Aegypt.-Arab. 185 (1775).T: Arabia, P.Forsskål; holo: C n.v.; photo seen (IDC microfiche 2200/2.83/22). Epithet is Latin for toothed, in reference to the supposedly dentate margins to the pinnae.
Aspidium molle Sw., J. Bot. (Schrader) 1800(2): 34 (1801); Nephrodium molle (Sw.) R.Br., Prodr. 149 (1810).T: Caracas, Colombia, N.T. von Jacquin?; holo: not traced.
Nephrodium remotum Heward, London J. Bot. 1: 121 (1842).T: Norfolk Island, A.Cunningham 21**; holo: K.
Cyclosorus nymphalis (G.Forst.) Ching, Bull. Fan Mem. Inst. Biol. 10: 247 (1941).T: New Zealand, G.Forster; syn: K.
[Aspidium parasiticum auct. non (L.) Sw.: J.H.Maiden, Proc. Linn. Soc. New South Wales 28: 735 (1904)]
[Dryopteris parasitica auct. non (L.) Kuntze: W.W.Watts, Proc. Linn. Soc. New South Wales 37: 396 (1913)]
Rhizome at most very shortly creeping. Fronds 40–50 cm tall; stipes borne close together; pinnae 15–25 pairs, 6–10 (–14) cm long, the lower 3–6 pairs gradually reduced in length to c. 2–3 cm long, lobed for the lower 2/3; lobes rounded, slightly oblique; hairs on rachis, costae and veins pale, 0.2–0.5 mm long, slightly longer hairs on upper surface, below with minute, erect hairs between veins. Sori circular; indusia hairy.
Norfolk Is., Lord Howe Is. This species is probably cosmopolitan, having a wide distribution throughout the tropics and subtropics of the Old World, including Australia, North Is. of New Zealand, and the Pacific islands.