Nephrolepis falciformis J. Sm. 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 : 303-304

11. Nephrolepis falciformis J. Sm. Map 7; Plate 2g

Nephrolepis falciformis J. Sm. (1866) 287 . - Type: Anon. s.n. ( BM), Borneo.

Nephrolepis thomsonii Alderw. (1917) 2 . - Type: Thomson 690 ( BO, L), New Guinea.

Nephrolepis cordifolia (L.) C. Presl var. calcarea H. Christ (1909) 158 . - Type: Versteeg 1614 (1603?) ( BO, K), New Guinea.

Nephrolepis falcata auct. non (Cav.) C. Chr.: Holttum (1968) 381; Tagawa & K. Iwats. (1985) 176.

Habit, rhizome morphology. Plants forming tufts of 2-4 fronds. Runners 1-2 mm thick, frequently branched, branching divaricate. Scales on runners sparse, appressed. Tubers absent. Fronds 150-200 cm long (or more), 9-14 cm wide, stipe 16-45 cm long. Lamina base reduced, tapering over 20-50 cm, basal pinnae 1.5-2.5 cm long, 4.5-5 cm distant, middle pinnae usually strongly falcate (basal and apical pinnae usually far less so). Sterile pinnae 5-6 by 1.1-1.8 cm, herbaceous, thick (often conspicuously pale green when dry), base strongly unequal, basiscopic base rounded, acroscopic base truncate, slightly to distinctly auricled, margin in basal part entire or crenate, apex acute or acuminate. Fertile pinnae 5.3-8 by 1-1.3 cm, with a more distinctly dentate margin than from sterile pinnae. Indument. Basal scales peltate, appressed, 3.5 by 1 mm, central part dark brown, dull, hyaline margin wide, distinct, ciliate throughout, marginal glands absent. Rachis scales sparse, without a distinctly protracted acumen, appressed, dark, conspicuous especially when dry. Scales on lamina sometimes present, very small, inconspicuous. Hairs on lamina absent, on costa sometimes present, few (usually forming a small group of scattered hairs near the base). Sori submarginal, 21 or 22 pairs on fully fertile pinnae, round, slightly impressed. Indusium reniform, with narrow sinus, attached at sinus.

Distribution - Sri Lanka, Indochina, Malesia: Peninsular Thailand, Sumatra, Malay Peninsula, Borneo, Celebes, Moluccas, New Guinea.

Habitat & Ecology - At low to middle elevation (sea level to 800 m, rarely higher), in forests, often in shade, also in open places, terrestrial or epiphytic.

Notes - A fairly distinct species, most easily recognizable by the strongly falcate median pinnae and the strikingly light colour (fresh plants are bright green, dry specimens often, but not always, a pale yellowish brown). The degree to which the pinnae are falcate strongly varies within a single frond, with the median fertile pinnae often very pronouncedly falcate, with the apex frequently curved back somewhat towards the midrib, but the more basal and apical pinnae usually only slightly or not at all falcate. The sori are mostly nearly marginal, some hairs are usually present on the upper surface of the costae especially near the points of attachment, often forming a rather characteristic sparse tuft. The scales on rachis are small and sparse, but rather conspicuous due to the dark colour.

A distinct form occurs on New Guinea, which differs from the typical form in a number of aspects: fronds long, slender, often stated to be pendent, often many in a tuft, strongly narrowed at base to strongly reduced (semicircular) basal pinnae, middle pinna relatively small and not strongly falcate; rachis and fronds nearly glabrous, scales where present small. Typical plants of this form are at frst sight similar to N. cordifolia , and have been distinguished as N. thomsonii and N. cordifolia var. calcarea. However , as all the characters that distinguish this form from typical N. falciformis show a very gradual transition between the two extreme states, we prefer to deal with it informally under this species.