Mostly epiphytic ferns, sometimes terrestrial or rupestral; rhizome mostly creeping, sometimes scandent, bearing peltate-based, often clathrate scales, dictyostelic. Fronds mostly long-stipitate, mostly articulate to the rhizome, vascular bundles several to numerous in a simple ring, lamina simple, pinnatifid or pinnate (rarely digitately lobed), sometimes the lobes articulate to the rhizome, glabrous, sometimes hairy, or with stellate hairs or scales, veins mostly anastomosing with included free veinlets. Sori exindusiate, round or elliptical, sometimes elongate and linear, sometimes on contracted lobes or portions or lamina, sometimes spreading over large surfaces of the lamina and contracted or not (acrostichoid); annulus longitudinal, interrupted; spores monolete.
A large, mostly tropical family of c. 50 - 60 genera and perhaps more than 1000 species. In Papuasia there are c. 20 genera with more than 150 species; a single genus could be considered aquatic.
Small to large, erect to pendulous, terrestrial, epiphytic or scandent ferns, sometimes aquatic or in swamps. Rhizome short- to long-creeping, moderately to densely covered with peltate-based, clathrate (at least in part) scales, dictyostelic. Fronds long-stipate, thestipe terete or winged, articulate to the rhizome or to distinct phyllopodia, rarely not articulate, fibrovascular bundles several to many in an open ring, lamina simple to pinnatifid, margin entire, glabrous or with scattered peltate scales, membranous to chartaceous or thin-coriaceous, prominently costate, venation reticulate, generally with indistinct main lateral veins, the areoles irregular with simple or forked included free veinlets pointing in all directions, ending in swelling or hydathodes. Sori exindusiate, at the junctions of veins between areoles, small, scattered over the lamina, generally superficial, or large circular or oval in one or several rows either side of the costae, generally moderately or strongly immersed and prominent on the upper surface, sometimes with paraphyses with enlarged apices, annulus longitudinal, interrupted, or 14 -16 thickened cells. Spores monolete, smooth or tuberculate.
Distribution: An large genus of 60 to perhaps 100 species in Old World tropics, subtropics and southern temperate regions. In Pauasia there are about 30 species, mostly epiphytes.
Croft, J.R. 1985. Ferns and Fern Allies, in Leach, G.J. & Osborne, P.L. 1985. Freshwater Plants of Papua New Guinea. 33 - 74, f. 6 - 13, pl. 5 - 7.
Copeland, E.B. 1958 - 1960. Fern flora of the Philippines. Vol. 1 - 3. Manila Bureau of Printing. 1 - 555.
Holttum, R.E. 1954 (revised 1965). Ferns of Malaya. A revised flora of Malaya. Volume 2. 1 - 643. Incl. Appendix by I. Manton, Cytological notes on 100 species of Malayan ferns. Govt. Printer, Singapore.
In Papuasia 3 species could be considered aquatic:
|1||Fronds small to moderate in size, simple, or pinnatifid with fen pinnae, lamina thin and papery, plant totally immersed in running water or rheophytic on river banks; sori small, superficial and indistinct…||... 2|
|Fronds large and erect, deeply pinnatifid with many pinnae, lamina thick, +/- leathery, plant in still, swampy conditions, or on floating mats of vegetation, at most only rhizome in water; sori large and deeply immersed in frond…||M. ? schneideri|
|2||Fronds always simple, c. 1 cm wide, the sori +/- in a single row either side of the midrib…||M. brassii|
|Fronds simple to mostly trifid, the lobes 2 - 3 cm wide, the sori scattered over the surface of the frond…||M. pteropus|
Terrestrial, beside or in streams, awash at high water. Rhizome thin and creeping, 1 - 1.5 mm diameter, clothed in thin, clathrate, peltate-based, scales c. 2 mm long, stipes 1 - 2 cm apart, 1 - 3 cm long, not articulated to the rhizome, with scattered scales, such scales also present along the midrib in young fronds, lamina simple, narrow, 10 - 20 cm long, 8 - 14 mm wide, gradually tapering into an acute tip, base gradually narrowed and decurrent into the stips, margin entire, texture thin and papery, when fresh the veins prominent below and the lamina between them raised on the upper surface (bullate), main veins 4 - 5 mm apart forming a single series of large areoles either side of the midrib, finer veins forming secondary areoles within and outside these. Sori very small +/- in a single row, the row sometimes irregular, midway between the midrib and margin, generally with 1 - 2( - 3) sori in each major areole.
Habitat: Between high and low water levels on small streams at low altitudes between 30 and 500 m, on or among soft or moss-covered rocks. The population from Manus was completely immersed when collected, and there was no reason to believe that the water was below its normal level. The thin fronds would not be able to withstand long periods without water. Other populations could more correctly be considered rheophytic in the sense of van Steenis (van Steenis 1981).
Distribution: The New Guinea mainland and Manus Island, but possibly more widespread. It is most frequently collected from the lowlands south of the diving range.
Notes: This is a very rarely collected species, and the application of the name is tentative, based on the original description. It appears closely related to Microsorium pteropus and both species sometimes occur together (eg. Pongani Falls gorge in the Northern Province). It may be a very reduced form of this species with contracted simple fronds and more or less uniseriate sori. The type is described as glabrous (Copeland 1929), but two specimens (NGF 7193, LAE 72497) have very short, fine dark hairs on the lower surface.
Terrestrial, beside steams, awash at high water. Rhizome creeping, 2 - 4 mm diameter, clothed in dark, clathrate, peltate-based scales c. 2 mm long, stipes 1.5 - 2 cm apart, 3 - 8 cm long, not obviously articulated to the rhizome, with scattered scales, such scales also present along the midribs in young fronds, lamina 15 - 25 cm long, simple or mostly with 1 - 2 lateral lobes, the apical lobe the largest, the lateral lobes inserted near its base, the lobes 2 - 4 cm wide, gradually tapering into an acute tip, base gradually narrowed, margin entire, base of frond gradually narrowed and decurrent into the stipe, texture thin and papery , when fresh the veins prominent below and the lamina between them raised on the upper surface (bullate), main veins 5 - 7 mm apart reaching ¾ towards the margin and arching, enclosing many secondary areoles. Sori small, round or slightly elongate along the veins, scattered irregularly between the major lateral veins.
Habitat: Beside flowing streams or water falls, or in swamp forests, always in full or partial shade, on mossy rocks or in mud. At low elevations from 25 to 5000 m altitude. Capable of immersion for considerable periods; Holttum (1954) notes that in seasonal areas this species is immersed for most of the wet season and could be called amphibious. In Irian Jaya Brass noted on field labels that it was a 'characteristic ground plant of swamp forests'.
Distribution: India and southern China through south east Asia, the Philippines and Indonesia to New Guinea. In Papuasia scattered collections from central Irain Jaya to the Central and Northern Provinces of Papua New Guinea. Like many swamp and aquatic plants it is infrequently collected.
Notes: This species appears to be closely related to the simple fronded aquatic ferns that are here referred to as Micosorium brassii. It is possible that the more or less uniseriate sori in M. brassii are the result of the simplification and contraction of the fronds. It is interesting to note that both forms occur together in the Pongani Falls gorge in the Northern Province.
Rhizome creeping, 7 - 10 mm diameter, fleshy, green, naked except towards the growing tip, the scales thin, pale, clathrate, broadly ovate, c. 2 - 3 mm long, stipes 5 - 10 cm apart, articulate to phyllopodia 5 - 7 mm high; fronds to over 1.5 m long including stipe to 50 cm, lamina narrowly lanceolate, to 20 cm broad, very deeply pinnatifid to almost pinnate at the base, the basal pinnae only slightly reduced, the lobes at c. 45 degrees to the midrib, narrow-oblong, 4 - 15 x 0.5 - 1.5 cm, tapering apically to a point, entire to slightly undulate, slightly leathery, glabrous; main veins 4 - 8 mm apart, forming a single series of large areoles either side of the midrib each containing many smaller areoles formed by finer veins. Sori Large, 2 - 4 mm diam., in a single row either side of the midrib, mid way between the midrib and margin, central in the larger areoles, deeply immersed in the lamina, strongly prominent as raised lumps 1 - 2 mm high on the upper surface.
Habitat: Low to mid elevations from 30 to 1500 m altitude, in swamps or swampy conditions, or on floating mats of vegetation in still waters, in full sun or partial shade.
Distribution: Assam, Indochina and the Philippines through Indonesia to New Guinea. In Papuasia it is infrequently collected, scattered along the north coast of mainland New Guinea from Jayapura to Milne Bay, and from Los Negros Island, Manus.
Notes: There is some confusion as to the correct application of the name of this species. It is very closely related to Microsorium alternifolium (Willd.)Copel. (syn. M. nigrescens (Bl.)Alston), and several other closely related species, which are sometimes difficult to separate (Holttum 1954); M. alternifolium typically has about half as many lobes to the frond and they are about twice as wide and thin and papery. The name Microsorium longissimum is not available for this species as it is already in use for a simple-fronded epiphyte. M. schneideri may be an available name (Copeland 1960); the type of this species comes from Sumatra.