Nephrolepis abrupta (Bory) Mett. - Map

Hovenkamp PH & Miyamoto F, 2005, A conspectus of the native and naturalized species of Nephrolepis (Nephrolepidaceae) in the world, Blumea 50, pp. 279-322 : 288-289

1. Nephrolepis abrupta (Bory) Mett. - Map 1

Nephrolepis abrupta (Bory) Mett. (1856) 99 ; J. Sm. (1875) 227. - Dicksonia abrupta Bory (1804) 187, pl. 30. - Leptopleuria abrupta (Bory) C. Presl (1836) 137, pl. 5, f. 9-11. - Type: Anon. s.n., s.d. ( K, L, P), Réunion.

Habit, rhizome morphology. Runners 1-2 mm thick, branching angle divaricate. Scales on runners dense, spreading or squarrose. Tubers absent. Fronds to 200 cm long (or much longer), 15-19 cm wide, stipe 30-35 cm long. Lamina base strongly reduced, tapering over 20-60 cm, basal pinnae 1-1.2 cm long, 2.5-6 cm distant, middle pinnae slightly to strongly falcate (mostly the cauda only is falcate). Sterile pinnae 3-13 by 0.8-2.8 cm (usually distinctly triangular, narrowed gradually from base to apex), leathery, base strongly unequal, basiscopic base cordate (strongly, sometimes somewhat auriculate), acroscopic base cuneate, truncate, rounded or cordate (always less distinctly cordate than the basiscopic base), not or slightly auricled (usually distinctly dilated, but not auricled), margin in basal part finely crenate, towards apex crenate, apex rounded, obtuse or acute. Fertile pinnae 3.2-14 by 0.7-1.8 cm, differing from sterile pinnae in the margin being incised between sori but not beyond the attachment. Indument. Basal scales pseudopeltate, spreading, 5.5 by 1 mm, central part rufous, shining (translucent), hyaline margin absent, marginal glands absent, margin in basal part fmbriate, acumen fmbriate, transition to rachis scales abrupt or basal scales persisting to high up. Rachis scales sparse or dense, with a well-developed protracted ciliate acumen, appressed or spreading, light brown or rufous. Scales on lamina absent. Hairs on lamina absent or present, short, dense. Sori marginal, 14-34 pairs on fully fertile pinnae, elongated, not impressed. Indusium broad, attached at broad base.

Distribution - Indian Ocean: Madagascar, Comores, Réunion; Malesia: Malay Peninsula, Borneo.

Habitat & Ecology - Lowlands to 800 m, often in pioneer vegetation on recent lava flows, also in degraded forest, in the eastern part of the range usually terrestrial, on limestone, sometimes epiphytic.

Note - Nephrolepis abrupta is somewhat similar to N. dicksonioides and has been confused with that species, from which it differs in more triangular pinnae, gradually narrowed from the base towards the apex, the fertile pinnae not incised beyond the sori, so that the sori are protruding from the margin, not on distinct teeth, indusium not reaching margin, innervated by 1, rarely 2 veins, rachis scales more strongly lacerated. The pinnae often appear to stand in a plane at right angles to the rachis. They are usually glabrous, but may be densely short-hairy all over the lamina, with hairy and glabrous fronds sometimes occurring on the same plant. Plants from the eastern part of the range are often larger than those from the western part, which are, especially those from the Comores, often compact and densely scaly in the lower part of the lamina. The more compact habit of these plants is not preserved in cultivation.