Nephrolepis biserrata (Sw.) Schott, 1834

Hovenkamp PH & Miyamoto F, 2005, A conspectus of the native and naturalized species of Nephrolepis (Nephrolepidaceae) in the world, Blumea 50, pp. 279-322 : 290-293

3. Nephrolepis biserrata (Sw.) Schott - Fig. 1g; Map 2; Plate 1b

Nephrolepis biserrata (Sw.) Schott (1834) ad. Pl. 3 ; Brack. (1854) 213; Merr. (1918) 43; Backer & Posth. (1939) 92; Copel. (1958) 187; Holttum (1968) 380; Tagawa & K. Iwats. (1985) 175; Proctor (1989) 265; Nauman (1992) 286; Verdc. (2001) 3; Mickel & A.R. Sm. (2004) 404. - Aspidium biserratum (Sw.) Sw. (1801) 32 ; (1806) 46. - Hypopeltis biserrata (Sw.) Bory (1833) 65 . - Lepidonevron biserratum (Sw.) Fee (1852) 301 . - Nephrodium biserratum (Sw.) Desv. ( 1827) 253 ; C. Presl (1830) 31. - Type: Groendal s.n. ( S n.v.), Mauritius.

Tectaria fraxinea Cav. (1801) 250 . - Type: Nee s.n. ( BM, fragm., MA), Philippines.

Aspidium acutum Schkuhr (1804) 32, t. 31 ; Sw. (1806) 46. - Nephrodium acutum (Schkuhr) C. Presl (1830) 31. - Hypopeltis palmoides (Schkuhr) Bory (1833) 50 (nom. superfl.). - Nephrolepis acuta (Schkuhr) C. Presl (1836) 79 ; Baker (1867) 301. - Type: Schkuhr (1804) 32, t. 31.

Aspidium ensifolium Schkuhr (1804) 32, t. 32 ; Sw. (1806) 46; Blume (1828) add. et emend. - Nephrolepis ensifolia (Schkuhr) C. Presl (1836) 79 . - Type: Schkuhr (1804) 32, t. 32.

Polypodium punctulatum Poir. (1804) 533 . - Nephrolepis punctulata (Poir) C. Presl (1836) 79, pl. 2 . - Type: Sonnerat s.n. (P-Lamarck n.v.), Martinique.

Aspidium punctulatum Sw. (1806) 46. - Lepidonevron punctulatum (Sw.) Fee (1852) 301 ; (1866) 87. - Nephrodium punctulatum (Sw.) Desv. (1827) 253 . - Type: Plumier, Fil. p. 98, pl. 112.

Aspidium splendens Willd. (1810) 220 ; Blume (1828) 147. - Nephrolepis splendens (Willd.) C. Presl (1836) 79 ; Brack. (1854) 212; J. Sm. (1875) 227. - Type: D. Klein (Willdenow herb. 19740, B), Ceylon.

Aspidium acuminatum Willd. (1810) 221 . - Nephrodium acuminatum (Willd.) C. Presl (1830) 31 . - Nephrolepis acuminata (Willd.) C. Presl (1836) 79 (non Kuhn 1869). - Lepidonevron acuminatum (Willd.) Fee (1852) 301 . - Type: Fluegge s.n. (Willdenow herb. 19741, B), America.

Aspidium gibbosum Willd. (1810) 222 . - Nephrodium gibbosum (Willd.) Gaudich. (1828) 338 . - Nephrolepis gibbosa (Willd.) C. Presl (1836) 79 . - Type: Nee? s.n. (Willdenow herb. 19743, B).

Aspidium paraense Willd. (1810) 228. - Nephrolepis paraensis (Willd.) C. Presl (1836) 79 . - Type: Hoffmansegg s.n. (Willdenow herb. 19752, B).

Nephrodium rufescens Schrad. ( 1824) 896. - Aspidium rufescens (Schrad.) Kunze (1839b) 34. - Lepidonevron rufescens (Schrad.) Fee (1852) 301; (1866) 87. - Nephrolepis rufescens (Schrad.) Wawra (1866) 200, t. 201. - Type: Anon. s.n. (herb. Mart., BR), locality unknown.

Aspidium paludosum Raddi (1825) 29, t. 44 (non Blume 1828 nec Mett. 1858). - Type: Raddi s.n. ( K).

Aspidium bidentatum Spreng. (1827) 99 . - Lepidonevron bidentatum (Spreng.) Fee (1852) 301 . - Nephrodium bidentatum (Spreng.) C. Presl (1830) 32 . - Nephrolepis bidentata (Spreng.) C. Presl (1836) 79 . - Type: Haenke s.n. ( PRC), Marianas.

Nephrodium timoriense Desv. (1827) 253 . - Type: Anon. s.n. ( P).

Polypodium palmoides Bory (1833) 50 . - Type: Bélanger s.n. ( P), Java.

Hypopeltis amygdalina Bory (1833) 64 . - Type: Bélanger s.n. ( P), Java.

Polypodium flagelliferum Roxb. (1844) 487 . - Type: Anon. s.n. ( BR), locality unknown.

Nephrolepis depauperata de Vriese (1846) 9 . - Type: Reinwardt 1680 ( L), Java.

Nephrolepis zollingeriana de Vriese (1846) 10 . - Type: Zollinger 146 ( L).

Nephrolepis platyotis Kunze (1850) 268, 312 . - Type: Anon. s.n., cult. Hortus Lips. (n.v.).

Nephrolepis macrophylla C. Presl (1851) 43 . - Type: Cuming 22 ( BM, PRC), Philippines.

Lepidonevron biauritum Fee ( 1852) 301 . - Nephrolepis biaurita ( Fee) C. Presl (1851) 43 . - Type: Hilsenberg s.n. (herb. Sieber 297) ( BM, G, K), Mauritius.

Nephrolepis acuta (Schkuhr) C. Presl var. laurifolia H. Christ (1897) 355 . - Nephrolepis laurifolia (H. Christ) Proctor (1989) 262 . - Lectotype (Proctor (1989) 262): Reinecke 1-d ( B? n.v.; iso L).

Nephrolepis persicifolia H. Christ (1909a) 159. - Type: Versteeg 1017 ( BO, K, L, P), New Guinea.

Nephrolepis caudata H. Christ (1909b) 27. - Type: Pynaert 1027 ( BR, photo BM), Congo.

Nephrolepis pilosula Alderw. (1913) 18 . - Type: Amdjah 542 ( BO).

Pteris signata Merr. (1918) 43 . - Type: unknown.

Nephrolepis dayakorum Bonap. (1918) 399 . - Type: Native collector? 70 ( BM, fragm., P), Borneo.

Nephrolepis mollis Rosenst. (1925) 13 . - Type: Brade & Brade 141 ( NY, S, UC), Costa Rica.

Habit, rhizome morphology. Plants forming tufts of 3-5 fronds. Runners 1-2.5 mm thick, branching angle divaricate. Scales on runners very sparse to dense, spreading or squarrose. Tubers absent. Fronds 120-160 by 19-25 cm, stipe 29-42 cm long. Lamina base truncate, tapering over 40-50 cm, basal pinnae 3.5-4 cm long, 4.5-5 cm distant, middle pinnae straight or slightly falcate (or somewhat recurved). Sterile pinnae 8-11 by 1.5-2 cm, herbaceous, thick or leathery, base equal or slightly unequal, basiscopic base cuneate, truncate or rounded, acroscopic base cuneate or truncate, slightly to distinctly auricled, margin in basal part crenate, towards apex serrate or dentate, apex obtuse, acute or acuminate. Fertile pinnae 9-15 by 0.9-1.3 cm, more strongly serrate than the sterile pinnae. Indument. Basal scales pseudopeltate, spreading (often somewhat falcately curved), 5 by 0.8 mm, central part light brown, shining, hyaline margin present in lower part only, marginal glands present around the base, marginal glands small, margin in basal part fmbriate, acumen dentate, apex entire. Rachis scales sparse or dense, spreading, hyaline or light brown, with a well-developed protracted entire acumen. Scales on lamina usually persistent. Hairs on lamina absent or sometimes present, costa sometimes present. Sori submarginal or medial, 50 pairs on fully fertile pinnae, round, not impressed. Indusium reniform, with narrow sinus, attached at sinus.

Distribution - Pantropical.

Habitat & Ecology - Usually in lowlands (sea level up to 750 m, rarely higher, to 1500 m), in open, disturbed situations, occasionally in forest; epiphytic or terrestrial. In Kalimantan reported as covering large tracts of recently burned forest.

Notes - Nephrolepis biserrata is very variable in frond size, shape of pinna-base, width of pinnae, hairiness, and to a lesser degree position of the sori. In Southeast Asia, pubescent forms occur mainly on Borneo, where they seem to be increasing as a result of recent forest fres - the burnt areas are quickly covered with a dense mat of sterile specimens of this form - and on New Guinea. Among American and African material, pubescent (sometimes densely so) specimens are common and more widespread, apparently not restricted to a narrow subrange. There may also be some size differences, with African material usually distinctly smaller than that from other locations.

Here we follow the traditional, wide circumscription of N. biserrata , which includes all Nephrolepis-forms with clearly inframarginal to medial sori with narrow sinus. Other rather constant characters are the basal stipe scales, which are uniformly narrow, concolorous and spread out sideways in one direction and the generally fairly large size of the plants. However, it is possible that in this circumscription a number of cryptic species are included. Herbarium studies may not be able to resolve these species partly for the usual reasons: lack of complete, well-documented specimens. As in many other cases, currently collected specimens appear to be collected with the aim to document the presence of known species only, not to help in distinguish unknown ones. It must be feared that the advent of fast ʻbiodiversity assessmentsʼ will do nothing to remedy this situation.

A very distinct form occurs on Ascension Island. In this form, the basal scales are spreading/ascending, narrow, slightly bicolorous, entire. The fronds are rather short, widest in the middle and strongly narrowed towards base, with basal pinnae reduced, often to short auricles. Pinnae are often slightly auricled acroscopically, then a little pinched and widening again to c. halfway, with obtuse to acute apex. All parts of the fronds are densely covered in hairs. The sori are closer to the margin than is typical for N. biserrata , and the ripe sori have inconspicuous, shrivelled indusia. An exactly similar specimen was collected on the coast of Brazil: Lindeman 6380 ( K, U). In morphology, this specimen is connected via a number of intermediates to more normal N. biserrata as occurring in South America, where specimens are mostly hairy, and indusia are inconspicuous in the ripe sori.

Nephrolepis platyotis probably represents an aberrant form (see under Cultivars and Monstrosities) with large acroscopic auricles.