9. Nephrolepis exaltata (L.) Schott - Map 6

Nephrolepis exaltata (L.) Schott (1834) Pl. 3; Brack. (1854) 211; Baker (1867) 301; Backer & Posth. (1939) 91; Copel. (1958) 188; Proctor (1989) 262; Nauman (1992) 287; Verdc. (2001) 4; Mickel & A.R. Sm. (2004) 406. - Polypodium exaltatum L. (1759) 1326. - Aspidium exaltatum (L.) Sw. (1801) 32; R. Br. (1810) 148; Blume (1828) 146. - Nephrodium exaltatum (L.) R. Br. (1810) 148; Desv. (1827) 252. - Hypopeltis exaltata (L.) Bory (1833) 66. - Type: Sloane s.n. (1: 52, BM n.v.), Jamaica.

Nephrolepis cultrifolia C. Presl (1836) 79. - Type: Meyen 1835 (PRC), Ouwahu. Nephrolepis neglecta Kunze (1839a) 149. - Type: Schiede 766a (lost, photo in BM), Mexico. Nephrolepis dentata Goldm. (1843) 463. - Type: Meyen s.n. (n.v.), Hawaii. Nephrolepis exaltata (L.) Schott subsp. hawaiiensis W.H. Wagner et al. (1999) 182. - Type: Wagner et al. 9621 (MICH n.v.), Hawaii.

Habit, rhizome morphology. Plants epiphytic or terrestrial (less often epilithic), forming tufts of 4 or 5 fronds. Runners 0.2-1.5 mm thick. Scales on runners sparse, spreading. Tubers absent. Fronds 40-150 by 5-12 cm, stipe 2-39 cm long. Lamina base strongly reduced, tapering over 20-25 cm, basal pinnae 0.6-3 cm long, 2-2.5 cm distant, middle pinnae slightly to distinctly falcate. Sterile pinnae 2.3-7.4 by 0.6-1.8 cm, herbaceous, thick, base slightly to strongly unequal, basiscopic base truncate, rounded to cordate, acroscopic base truncate, distinctly auricled, margin in basal part entire or crenate, towards apex more deeply serrate or dentate, apex obtuse or acute. Fertile pinnae 2.3-5.9 by 0.6-1.5 cm, otherwise similar to sterile ones. Indument. Basal scales peltate, spreading, 2-9 by 0.4-1.3 mm, central part light brown or dark brown, dull, margin not hyaline, in basal part entire, denticulate or dentate, in acumen entire or denticulate, marginal glands absent. Rachis scales with a well-developed protracted acumen. Scales on lamina sometimes present. Hairs on lamina absent, on costae absent. Sori submarginal or medial, 9-16 pairs on fully fertile pinnae, round or elongated, not impressed. Indusium reniform, with open sinus, attached at sinus or at broad base.

Distribution - Florida, the Bahamas, Turks & Caicos, Cuba, Hispaniola, Puerto Rico, Jamaica, Mexico (Veracruz only), Bermuda, Panama, French Guyana (one specimen seen), Hawaii. The occurrence on Henderson and Rapa reported by Brown & Brown (1931) is so far not confrmed.

Habitat & Ecology - Occurs in a variety of habitats, at low to middle elevations (sea level to 1170 m).

Notes - Nephrolepis exaltata is supposed to be the source for N. ʻbostoniensisʼ and all cultivars derived from it, which are widely cultivated. The name has been widely, and mistakenly, applied to specimens from all over the world.

Introductions: contrary to what might be expected, N. exaltata does not seem to naturalize often outside its native range. Most of the naturalized occurrences concern islands in the Atlantic, and may be diffcult to distinguish from native occurrences. On the Canary Islands, it is considered as an introduction by Hohenester & Wells (1993), but on Bermuda as native by Britton (1918). One collection was seen from St Helena (Packer HL 10, Jamestown), where it is possibly introduced. Some specimens are apparently collected in the wild in Africa and are regarded as naturalized escapes by Verdcourt (2001). Specimens were collected on the Hawaiian Islands as early as 1788 (David Nelson s.n., BM) 1825 (Macrae s.n., BM) and 1837 on Oahu (Barclay 1227, BM), and N. exaltata should be regarded as native there. Wagner et al. (1999) distinguished the Hawaiian population as subsp. hawaiiensis on basis of a comparison with the Caribbean population, but most of their distinguishing characteristics fall within the range of N. exaltata if the Florida specimens are taken into account.