Aphyllorchis queenslandica

Pauper Orchids

Leafless terrestrial orchids that reproduce solely from seed. Plants have a sturdy flower stem that is often purplish and a terminal raceme of few-several flowers. The cupped flowers, which are up the right way, are basically cream, white or yellowish with sepals and petals all of similar length. The dorsal sepal, which curves close to the column is broader than the lateral sepals and the petals can be of similar width to the lateral sepals or narrower. The labellum has a short narrow basal part to which is flexibly attached an obscurely or distinctly 3-lobed blade. The obscurely winged column is narrow and curved without a foot.

Significant Generic Characters

Aphyllorchis is a leafless terrestrial genus characterised by thin wiry to sturdy scape that is often pallid, with numerous basal bracts and several sterile bracts; flowers on long ovaries, often not opening widely, resupinate, cream, white or yellowish; perianth segments of similar length, free, the dorsal sepal broader than the lateral sepals; lateral sepals and petals subsimilar or the petals narrower or wider; labellum with a short basal hypochile (absent in Aphyllorchis anomala) and 3-lobed epichile (unlobed in Aphyllorchis anomala), the epichile often flexibly attached to the hypochile; callus obscure, consisting mainly of a central plate, sometimes with sunken areas (absent in Aphyllorchis anomala); column narrow, curved, obscurely winged, without a column foot.

Size and Distribution

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A genus of about 30 species distributed in India, Sri Lanka, China, Taiwan, Thailand, Myanmar, Malaysia, Philippines, Indonesia, New Guinea and Australia. Two species are endemic in Australia where they are restricted to northeastern Queensland occurring in scattered disjunct localities between about 1530 S and 2110 S. State occurrence: Queensland.

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Ecology

Species of Aphyllorchis grow at low altitudes in moist humid forests, especially rainforest, and often near streams. Soils are commonly sands or loams rich in decaying litter and humus. Their subterranean stems have coarse thick unbranched roots that are sometimes quite short and stubby.

Biology

Pollination: The flowers of both native species of Aphyllorchis are self-pollinating. The self-pollination process takes place well before the flowers open.

Reproduction: Both native species of Aphyllorchis reproduce solely from seed. Seeds are dispersed 10-12 weeks after pollination. The capsules of Aphyllorchis anomala radiate stiffly from the rhachis whereas those of A. queenslandica are mostly pendulous. There is no increase in the length of the peduncle or pedicels during this process.

Seasonal Growth: The prevailing climate is tropical with a monsoonal wet season in the summer and drier winter with intermittent rain. The plants are subterranean for most of the year except when flowering or fruiting.

Flowering: Flowering appears to occur sporadically with a concentration of records between December and May.

Hybrids: Natural hybridisation involving Aphyllorchis is unknown.

Fire: Plants mostly occur in habitats that are not prone to fire.

Derivation

The generic name is derived from the Greek aphyllos, leafless and O rchis another genus of Orchidaceae but also applied generally to orchids.

Botanical Description

Perennial leafless geophytic herbs, deciduous, sympodial. Plants glabrous. Roots thick, fleshy, sometimes short, unbranched. Stem erect, short, unbranched, subterranean, multinoded, mostly vertical, with one or more apical cataphylls. Leaves absent. Inflorescence terminal, racemose, few-many-flowered, erect. Peduncle wiry to fleshy, glabrous, with several sterile bracts, pallid or often with purple suffusions. Sterile bracts short, sheathing at the base, sometimes the base sused around the peduncle. Floral bracts reduced, sheathing or spreading. Pedicels short, merging with the ovary at anthesis. Ovary elongate, ribbed, glabrous. Flowers resupinate, often not opening widely, pale coloured (cream, white or yellowish, sometimes with purple markings), shortly pedicellate. Sepals and petals of similar length. Dorsal sepal free, incurved, wider than the lateral sepals. Lateral sepals free, narrower than the dorsal sepal, divergent. Petals free, narrower or wider than the lateral sepals. Labellum free, divided into a hypochile (absent in Aphyllorchis anomala) and epichile; hypochile basal, short, narrow, stiffly attached the base of the column; epichile elongate, flexibly attached to the hypochile, 3-lobed, sometimes obscurely (unlobed in Aphyllorchis anomala), dissimilar in size and shape to the sepals and petals, ecalcarate. Callus obscure (absent in Aphyllorchis anomala), consisting mainly of a central plate, sometimes with associated fused calli or sunken areas. Nectar absent. Spur absent. Column elongate, narrow, incurved, lacking free filament and style. Column foot absent. Pseudospur absent. Column wings obscure, fused to the column, mainly apical. Anther terminal, 2-celled, persistent, basifixed, erect. Pollinarium absent. Pollinia 2, curved, mealy or powdery, yellow. Viscidium absent. Rostellum ventral, terminal. Stigma entire or bilobed, cordate, concave. Capsules dehiscent, glabrous, porrect or pendulous; pedicels not elongating in fruit; peduncle not elongating in fruit. Seeds numerous, light coloured, winged.

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Nomenclature

Aphyllorchis Blume, Bidjr., t. 77 (1825). Type species: Aphyllorchis pallida Blume.

References

Clements, M.A. (1990). Catalogue of Australian Orchidaceae. Austral. Orch. Res. 1: 1-160.

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.

Schlechter, R. (1982). The Orchidaceae of German New Guinea (English translation by R.S. Rogers, H.J. Katz and J.T. Simmons). Australian Orchid Foundation, Melbourne.