Epiphytes or lithophytes with prominent clustered fleshy pseudobulbs, each with several nodes, when young covered by brown papery bracts. Leaves 1-3 per pseudobulb, apical, thin-textured, longer than wide, flat. Racemes relatively long, arising from near the apex of a pseudobulb. Flowers lasting a few days, opening widely, with thin-textured segments. Lateral sepal bases fused with the column foot. Petals similar length to the sepals. Labellum hinged to the apex of the column foot, 3-lobed, with longitudinal ridges or keels.
Similar Genera
Significant Generic Characters
Epiphytic/lithophytic orchids; rhizomes very short; pseudobulbs relatively large, fleshy, multinoded; leaves lasting several seasons, 1-3 per pseudobulb, apical, duplicate, thin-textured but tough, sometimes fleshy, longer than wide, articulated on the apex of the sheathing base, flat; racemes arising from subapical nodes of a pseudobulb, relatively long, multiflowered; peduncle and rhachis circular in cross-section, not winged; flowers lasting a few days, opening widely; perianth segments thin-textured, glabrous or pubescent; lateral sepal bases fused with the column foot; petals similar length to the sepals; labellum hinged to the apex of the column foot; lamina 3-lobed, thin-textured; callus with central keels or ridges.
Size and Distribution
A genus of about 50 species widely distributed in Asia, South-east Asia, Malaysia, Philippines, Indonesia, New Guinea and Polynesia with a single non-endemic species in Australia. The native species, Hymeneria fitzalanii, occurs on some Torres Strait islands and is widely distributed in northeastern Queensland between Cape York (10º41’S) and Mt Elliot (26º06’S) near Ayr. State occurrence: Queensland (including Moa Island).
Ecology
In Australia Hymeneria fitzalanii is restricted to tropical Queensland growing on trees and rocks in brightly lit, humid sites with free air movement. Plants commonly grow on mangroves and in other coastal vegetation, on trees overhanging streams, in rainforest, along rainforest margins and in humid areas of open forest. In its habitat the majority of rain falls during the summer wet season (December to March) with the remaining months being drier with sporadic or intermittent rain.
Biology
Pollination: The flowers of Hymeneria fitzalanii are generally short-lived but open widely and are insect-pollinated.
Reproduction: Reproduction in Hymeneria fitzalanii is solely from seed. Seed dispersal takes 2-4 months after pollination and the capsules develop in an erect position. Apomixis is unknown in the genus.
Seasonal Growth: The plants grow actively during the spring and summer months and are relatively quiescent for the remainder of the year.
Flowering: Flowering occurs mainly between August and October but sporadic flowering can occur at other times.
Hybrids: Natural hybrids involving Hymeneria fitzalanii are unknown.
Derivation
Hymeneria is derived from the Greek hymen, membrane and Eria, another genus of Orchidaceae.
Botanical Description
Perennial, evergreen, epiphytic or lithophytic herbs, sympodial. Plants hirsute. Roots elongate, filamentous, very thin, branched, produced from nodes on the base of the pseudobulb. Rhizome obscure, creeping, branched. Pseudobulbs well-developed, multinoded, fleshy, crowded, relatively long, when young covered by brown scarious bracts. Trichomes present on some floral parts. Aerial growths absent. Leaves lasting several seasons, terminal, 1-3 per shoot, distichous, duplicate, sessile or petiolate, longer than wide, thin textured, coriaceous, smooth, flat, not grooved or channelled, articulate on the apex of the sheathing base; base sheathing the pseudobulb; margins entire; apex unequally emarginate. Inflorescence racemose, elongate, erect to arcuate, arising from a lateral or subapical node on a mature pseudobulb, multiflowered. Peduncle shorter, equal to or longer than the rhachis, cylindrical in cross-section, glabrous or pubescent, with scattered scarious bracts. Floral bracts scarious, sheathing the base of the pedicel. Pedicel relatively short, thin, cylindrical, merging with the ovary, glabrous or pubescent. Ovary short, straight, non-twisted, porrect from the pedicel, glabrous or pubescent. Flowers resupinate, opening widely, stalked, lasting a few days, white, cream or yellowish. Perianth segments thin-textured, widely spreading, entire, glabrous or pubescent externally. Dorsal sepal free, narrower than the lateral sepals. Lateral sepals broader than the dorsal sepal, attached by their bases to the column foot to form a mentum. Petals free, narrower than the sepals. Labellum hinged to the apex of the column foot, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina 3-lobed, sometimes obscurely so; lateral lobes small to relatively large, erect to spreading, entire; midlobe short to elongate, porrect to decurved; apex entire or emarginate. Spur absent. Callus consisting of narrow, median, parallel ridges. Nectar absent. Column at an angle to the end of the ovary, lacking free filament and style, fleshy, shorter than the perianth segments, nearly straight. Column wings reduced, lateral, with short tooth-like apical stelidia. Column foot well developed, at right angles to the column. Pseudospur absent. Anther terminal, incumbent, small, 8-celled, persistent, attached dorsally by a ligulate claw, smooth, erostrate. Pollinarium present, consisting of pollinia attached by caudicles, sometimes with a rostellum. Pollinia 8 in 2 groups of 4, orange, hard, waxy, stalked. Viscidium small or absent. Rostellum ventral, swollen, transverse. Stigma entire or bilobed, transverse, concave. Capsules dehiscent, glabrous or hairy, erect; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Taxonomy
Hymeneria was recently raised to generic rank as being distinct from Eria based on thin filamentous roots, pseudobulbs of several nodes, each node with a papyraceous bract, leaves with obscure venation, inflorescences arising from subapical nodes, racemes with a cylindrical peduncle and rhachis, flowers thin-textured, often glabrous and narrow column with vestigial wings.
Nomenclature
Hymeneria (Lindl.) M.A.Clem. and D.L.Jones, Orchadian 13(11): 501 (2002). Type species: Eria obesa Lindl. [Hymeneria obesa (Lindl.) M.A.Clem. and D.L.Jones].
Infrageneric Taxa: Hymeneria requires a detailed study to elucidate infrageneric relationships.
References
Clements, M.A. and Jones, D.L. (2002). Nomenclatural changes in the Australian and New Zealand Bulbophyllinae and Eriinae (Orchidaceae). Orchadian 13(11): 498-501.
Dockrill, A.W. (1969). Australian Indigenous Orchids. Volume 1. The Society for Growing Australian Plants, Halstead Press, Sydney.
Dockrill, A.W. (1992). Australian Indigenous Orchids. Volume 1 & 2. Surrey Beatty & Sons in association with The Society for Growing Australian Plants, Chipping Norton, NSW.