Tonsil Orchids
Deciduous terrestrials with succulent, above-ground, creeping stems with an erect apex, anchored by wiry roots that appear woolly. The thin-textured leaves, carried in a basal rosette or scattered, are mostly stalked, rarely sessile. Spikes short to long, terminal on a shoot, glabrous or hairy. Flowers small, right-way-up, dull-coloured, glabrous or hairy. Dorsal sepal and petals overlapping to form a hood. Labellum attached to the anterior base of the column, with a deep basal spur that contains 2 large fleshy stalked glands.
Significant Generic Characters
Terrestrial orchids, deciduous; stems succulent, above-ground, creeping with an erect apex, anchored by wiry nodal roots that appear woolly; leaves petiolate, rarely sessile, in a basal rosette or scattered, relatively broad, glabrous, thin-textured; inflorescence spicate, short, terminal on a shoot; flowers resupinate, small, often short-lived, dull-coloured (greenish, yellowish, brownish, reddish, white), glabrous or hairy; dorsal sepal and petals overlapping to form a galea. Labellum attached to the anterior base of the column, with a deep basal spur; hypochile tapered or constricted; epichile obscure or well-developed, flat or pouched. Basal spur with two large fleshy stalked glands. Column short, with a deeply bilobed stigma.
Size and Distribution
A genus of 40-50 species distributed in tropical regions of India, Taiwan, South-east Asia, Malesia, Melanesia, Polynesia and Australia. A single species, Vrydagzynea grayi, is endemic in Australia where it was collected twice from a single locality in the Daintree River region of northeastern Queensland that has since been cleared. The species is unknown from other localities and is possibly extinct. State occurrence: Queensland.
Ecology
Species of Vrydagzynea grow in dark moist forests, particularly rainforest, in areas where there is constant high humidity. Some species grow as rheophytes on stream banks and can withstand being submerged by floodwaters; others grow on rotting logs and colonise road verges, ditches and track margins. In New Guinea the genus ranges from the lowlands to more than 1800 m alt. The native species, Vrydagzynea grayi, was recorded from outcrops of decomposed shale in lowland rainforest.
Biology
Pollination: Some species of Vrydagzynea are insect-pollinated whereas others are self-pollinating and some may be cleistogamous. The native species is self-pollinating.
Reproduction: Vrydagzynea reproduces solely from seed. Seed dispersal takes 1-2 months from pollination and the capsules develop in an erect position. In some species the peduncle elongates prior to seed dispersal. Apomixis is unknown in the genus.
Seasonal Growth: Vrydagzynea grayi probably survives the dry part of the year as leafless quiescent plants.
Flowering: Vrydagzynea grayi flowers September-October.
Hybrids: Vrydagzynea grayi does not participate in natural hybridisation.
Fire: Vrydagzynea grayi does not grow in fire-prone habitats.
Derivation
Vrydagzynea is named after the Dutch pharmacologist Theodore Daniel Vrydag Zynen.
Botanical Description
Perennial, deciduous, terrestrial herbs (rarely epiphytic), sympodial. Roots wiry, produced from rhizome nodes, appearing woolly from a covering of root hairs. Rhizome cylindrical, fleshy, unbranched or sparsely branched, prostrate. Stem erect, apical, usually 1 shoot per plant, similar to the rhizome. Pseudobulbs absent. Trichomes present or absent, if present unbranched, multiseriate, eglandular. Leaves lasting 1 season, few per shoot, sessile or petiolate, sheathing at the base, spirally arranged, forming a loose rosette or scattered up the stem. Leaf lamina not much longer than wide, thin, membranaceous, glabrous, flat, smooth, entire, light green, sometimes with a pale median band or coloured veins. Venation acrodromus to campylodromus, with cross-veinlets and few anastomoses. Inflorescence spicate, terminal on a growth, erect, few-many-flowered. Peduncle shorter or longer than the rhachis, glabrous or hirsute, with semi-sheathing, glabrous or hirsute sterile bracts. Floral bracts sheathing, glabrous or hirsute. Ovary elongate, asymmetric, straight or curved, twisted, glabrous or hirsute. Flowers resupinate, small, crowded, dull coloured (greenish, yellowish, reddish, brownish, white), sessile to subsessile, externally glabrous or hirsute. Sepals often with thickened tips. Dorsal sepal closely overlapping with the petals to form a galea. Lateral sepals free, mostly porrect. Petals shorter than the sepals, forming a galea with the dorsal sepal, membranous, often asymmetric. Labellum fixed by its basal margins to the anterior margins of the column base, immoveable, markedly dissimilar in size and shape to the sepals and petals, strongly calcarate. Labellum lamina divided into a hypochile and an epichile, these sometimes obscurely differentiated; hypochile equal to or longer than the epichile, entire, tapered or constricted distally; basal spur well-developed, conical, sometimes notched, containing 2 stalked fleshy smooth or verrucose glands; epichile obscure to well-developed, flat or concave, distal margins often incurved, sometimes flared or thickened; apex entire or emarginate. Callus obscure. Nectar absent. Column short, lacking free filament and style. Column wings absent or vestigial. Column foot absent. Pseudospur absent. Anther dorsal, 2-celled, persistent, basifixed, with an obtuse to acuminate rostrum. Pollinarium present. Pollinia 2, clavate, sometimes deeply grooved or lobed, straight or curved, yellow, sectile, either attached direct to a viscidium or via a stipe. Viscidium present, sometimes vestigial. Rostellum ventral, short to elongate, sometimes forming 2 arm-like structures. Stigma 1, deeply bilobed, the lobes parallel or divergent. Capsules dehiscent, glabrous or hirsute, erect, the valves often separating widely so the capsule appears nearly globular; peduncle sometimes elongating in fruit (usually not); pedicels not elongated in fruit. Seeds numerous, light coloured, winged.
Taxonomy
Within the subtribe Goodyerinae Vrydagzynea is distinguished by petals shorter than sepals and a well-developed basal spur on the labellum containing 2 fleshy stalked glands. Plants are most conspicuous in fruit and these orchids are uncommonly collected in flower. The flowers are rarely preserved in spirit so that useful features can be determined. For orchids with a simple general appearance the flowers exhibit a remarkable degree of specialisation. The genus has suffered badly from pigeonholing by botanists who do not view these orchids as a specialised group that has radiated into specific habitats.
Notes
The Australian species of Vrydagzynea was recently described as V. grayi (see Jones and Clements 2004).
Nomenclature
VrydagzyneaBlume, Collect. Orchidees 71 (1858). Type species: non designatus.
Infrageneric Taxa: No infrageneric taxa are recognised.
References
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.
Pridgeon, A.M., Cribb, P.J., Chase, M.W. and Rasmussen, F.N. (eds), (2003). Genera Orchidacearum, Vol. 3. Oxford University Press.
Jones, D.L. and Clements, M.A. (2004). Miscellaneous new species, new genera, reinstated genera and new combinations in Australian Orchidaceae. Orchadian 14(8): Scientific Supplementi-xvi.