BLECHNACEAE

Mostly terrestrial ferns, sometimes climbers starting from the ground, rhizome mostly erect, sometimes rampant, dictyostelic, bearing dark, basally attached scales. Fronds mostly long stipitate, the stipe with 2 to several bundles in a ring, or many bundles in a more complex arrangement, lamina pinnatifid or pinnate, cometimes simple, lobed, or bipinnatifid, uniform or with strongly contracted fertile pinnae or lobes, glabrous, hairy and/or scaly, veins free to the margin, or anastomosing in a single (rarely more) series of costal areoles. Sori elongate and continuous along a vascular network either side of the midrib, protected by an indusium opening inwards, less often exindusiate, sometimes sori short, occasionally confluent, in 1 - 2 rows; annulus longitudinal, interrupted; spores monolete.

A family of 11 genera world-wide, with c. 240 species. In Papuasia there are 4 genera with c. 33 species. Stenochlaena is the only genus that could be considered aquatic.

Stenochlaena J. Sm.

Moderate to large, high-climbing ferns with scandent rhizomes, often in swamps or beside rivers. Rhizome naked, green, apically bearing many rotund or elongate, peltate scales, radially symmetric, vascular system a complex dictyostele of several large central bundles surrounded by 2 irregular rings of many smaller bundles. Fronds widely spaced, stipes glabrous, +/- decurrent with the rhizome, with corresponding vasculature, the lamina pinnate with alternate pinnae and a terminal pinna similar to the lateral pinnae, dimorphic, the fertile lamina much contracted (in one species bipinnate); the sterile lateral pinnae usually articulate, with a basal acroscopic gland, costate with fine, close, free veins arising from a series of narrow, elongate, costal areoles, coriaceous, glabrous, margin cartilaginous and sharply toothed; fertile pinnae narrow, linear, entire. Sporangia borne in an elogate coena\osorus occupying the area from the costal areoles almost to the margin of the fertile pinnae, supplied by a secondary vascular system, exindusiate, paraphyses lacking, annulus longitudinal, interrupted, of 12 - 20 thickened cells. Spores monolete, translucent, tuberculate or with continuous or broken ribs.

Distribution: A genus of 6 species from Africa, Asia, the Philippines and Indonesia eastwards into the Pacific as far as Tonga and Samoa. There are three species in Papuasia, of which Stenochlaena areolaris is restricted to the crowns of some species of Pandanus (Pandanaceae).

References

Stenochlaena milnei Underw.

Scrambling, long creeping fern, or high climbing epiphyte with base rooted to the ground, fronds widely spaced, horizontal to pendulous with drooping pinnae, the rhizome 10 - 15 mm diameter, pale green, sometimes slightly glaucous, smooth, with scattered, dark, small, orbicular scales, especially towards the apex, the growing tip completely covered; fronds 100 - 150 cm long, including stipe 20 - 50 cm long, sterile pinnae for the most part not articulate to the rachis, lanceolate to oblong-lanceolate or oblong, 3 - 5 x 15 - 3- cm, tip acute, slightly attenuate, base often asymmetric, mostly rounded, with a small dark gland on the apical side, margin almost entire to serrulate, especially at the apex; fertile pinnae linear, 4 - 7 x 15 - 30 cm; spores with irregular broken ridges.

Habitat: Most collections indicated well-drained lowland rainforests, but some are from fresh water swamp forests, sago (Metroxylon) swamps, behind mangroves or strand vegetation, along rivers, etc., sometimes in full sun but prefers a partial shade, sometimes with Stenochlawna palustris. Most commonly a scrambling, high-climbing epiphyte; from sea level to 300 m altitude.

Distribution: The Philippines and New Guinea and the Bismarck Archipelago to the Solomon Islands. In New Guinea apparently restricted to along the north coast.

Notes: This species is closely related to Stenochlaena palustris and has often been misidentified in the past. S. milnei is a much more robust plant generally occuring in less swampy conditions than S. palustris. There are very few specimens that are not assignable to either or these species. The young leaves of this species do not appear to be eaten like Stenochlaena palustris, but this may be a reflection of the relative abundance of the two species.

Specimens examined:

Stenochlaena palustris (Burm.f.) Bedd.

Scrambling, long creeping fern, or high climbing epiphyte with base rooted to the ground, fronds widely spaced, horizontal to pendulous with drooping pinnae, the rhizome 5 - 7 mm diameter, pale green, sometimes slightly glaucous, smooth, with scattered, dark, small, orbicular scales, especially towards the apex, the growing tip completely covered; fronds 30 - 80 cm long, including stipe 5 - 20 cm long, sterile pinnae for the most part articulate to the rachis, lanceolate to oblong-lanceolate, 1.5 - 3 x 8 - 15cm, tip acute, slightly attenuate, base often asymmetric, mostly cuneate, with a small dark gland on the apical side, argin almost entire to serrulate, especially at the apex; fertile pinnae linear, 2 - 3 x 15 - 25 cm; spores evenly tuberculate.

Habitat: Fresh water swamp forests, sago (Metroxylon) swamps, behind mangroves or strand vegetation, along rivers, marshes and on floating vegetation, sometimes in full sun but prefers partial shade. Most commonly a scrambling, high-climbing ehiphyte in areas subject to periodic inundation, where the base of the rhizome and lower fronds are frequently wet, but also occurs in lowland rainforest in areas free from flooding; from sea level to 300 m altitude.

Distribution: India, throughout southeast Asia, Indonesia and New Guinea from nearly all lowland regions, and northeast Australia, and eastwards to Tonga and Samoa.

Notes: The juvenile leaves of this species are deep reddish. In some areas (Manus, Sepik, Upper Fly, Milne Bay etc.) these young fronds are harvested and cooked as a vegetable. (See also note under Stenochlaena milnei).

Holttum (1927) notes that the production of fertile fronds may be stimulated by a period of dry weather.

Specimens examined

Stenochlaena palustris (Burm.f.) Bedd.

Scrambling, long creeping fern, or high climbing epiphyte with base rooted to the ground, fronds widely spaced, horizontal to pendulous with drooping pinnae, the rhizome 5 - 7 mm diameter, pale green, sometimes slightly glaucous, smooth, with scattered, dark, small, orbicular scales, especially towards the apex, the growing tip completely covered; fronds 30 - 80 cm long, including stipe 5 - 20 cm long, sterile pinnae for the most part articulate to the rachis, lanceolate to oblong-lanceolate, 1.5 - 3 x 8 - 15 cm, tip acute, slightly attenuate, base often asymmetric, mostly cuneate, with a small dark gland on the apical side, margin almost entire to serrulate, especially at the apex; fertile pinnae linear, 2 - 3 x 15 - 25 cm; spores evenly tuberculate.

Habitat: Fresh water swamp forests, sago (Metroxylon) swamps, behind mangroves or strand vegetation, along rivers, marshes and on floating vegetation , sometimes in full sund but prefers partial shade. Most commonly a scrambling, high-climbing epiphyte in areas subject to periodic inundation, where the base of the rhizome and lower frond s are frequently wet, but also occurs in lowland rainforest in areas free from flooding; from sea level to 300 m altitude.

Distribution: India, throughout southeast Asia, Indonesia and New Guinea from nearly all the lowland regions, and northeast Australia, and eastwards to Tonga and Samoa.

Notes: The juvenile leaves of this species are deep reddish. In some areas (Manus, Sepik, Upper Fly, Milne Bay etc.) these young fronds are harvested and cooked as a vegetable. (See also note under Stenochlaena milnei).

Holttum (1927) notes that the production of fertile fronds may be stimulated by a period of dry weather.

Specimens examinded