Fruticicola radicans

Epiphytes or lithophytes with thin pendulous to arching, unbranched or sparsely branched rhizomes anchored to the host by filamentous roots arising from basal nodes and also with aerial roots that often grow along the rhizomes. Small single-noded pseudobulbs are crowded on the rhizomes. Each pseudobulb has a single moderately large terminal leaf that is longer than wide, flat and thick-textured to fleshy and with a downcurved tip. The flowers are borne singly at sporadic intervals from a multi-flowered inflorescence that arises from the base of a pseudobulb. The upside-down flowers, which are small, thin-textured and last a few days, are porrect to semi-nodding and have a no noticeable scent.  The petals are smaller than the sepals and the labellum, which is 3-lobed, fleshy and hairy on the underside, is firmly hinged to the apex of the column foot.

Similar Genera

Oxysepala

Significant Generic Characters

Epiphytic/lithophytic orchids; plants arcuate to pendulous; roots filamentous, arising from basal nodes and also with aerial roots that often grow along the rhizome; rhizomes thin, pendulous to arcuate, unbranched or sparsely branched; pseudobulbs small, single-noded; leaf single, flat, thick-textured to fleshy, with a downcurved tip; flowers non-resupinate, borne singly at sporadic intervals from a multi-flowered inflorescence arising from the base of a pseudobulb; perianth segments thin textured; petals smaller than the sepals; labellum firmly hinged to the apex of the column foot; labellum lamina 3-lobed, fleshy, hairy on the underside.

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Size and Distribution

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A genus of c. 25 species, the majority occurring in New Guinea, with a single species, Fruticicola radicans, endemic in Australia. It is restricted to tropical parts of north-eastern Queensland between the Big Tableland south of Cooktown (1540' S) and Crediton west of Mackay (2110' S) and is distributed from the coastal lowlands to the ranges and tablelands above 1000 m alt. State occurrence: Queensland.

Ecology

Fruticicola radicans grows in rainforest on trees or rocks on sheltered slopes and ridges in situations of moderate to bright light, high humidity and free air movement.

Biology

Pollination: The flowers of Fruticicola radicans last 3-4 days and are insect-pollinated, the vectors apparently being small flies that feed on nectar produced by the labellum.

Reproduction: Reproduction in Fruticicola is solely from seed. Seed dispersal takes 3-4 months after pollination. There is no increase in the length or thickness of the peduncle or pedicel during this process. Apomixis is unknown in the genus.

Seasonal Growth: The plants grow mainly between spring and autumn and are relatively quiescent for the remainder of the year.

Flowering: Flowering occurs sporadically through the year.

Hybrids: Natural hybrids involving Fruticicola radicans are unknown.

Derivation

The generic name Fruticicola is derived from the Greek frutex, fruticis, shrub or bush and  -cola, dweller or inhabitant, an apparent reference to some species growing on shrubs.

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Botanical Description

Perennial, evergreen, epilithic herbs, sympodial. Roots filamentous, wiry, produced from the base of a pseudobulb, distal nodes with aerial roots. Rhizomes attached to the host by roots from the basal nodes, the remainder arcuate to pendulous, thin, creeping, unbranched or sparsely branched from the base, covered by persistent, closely sheathing, imbricate, scarious bracts. Pseudobulbs appressed to the rhizome, more or less alternate, crowded, single-noded, small, cylindric, smooth, fleshy, flattened or broadly grooved on the side away from the rhizome, partly obscured by bracts. Trichomes absent. Leaves sessile, 1- per shoot, terminal on a pseudobulb, not sheathing at the base, flat to shallowly channelled, longer than wide, smooth, thick-textured, fleshy, coriaceous; apex unequal, decurved. Inflorescence arising from the base of a mature pseudobulb, multiflowered but each flower arising singly at sporadic intervals, erect. Peduncle longer than the pedicel, thin, with a single tubular, closely sheathing, membranous sterile bract at the base. Floral bract tubular, membranous, sheathing the base of the pedicel. Ovary short, curved at right angles to the pedicel and merging with it, smooth. Flowers non-resupinate, pedicellate, porrect to semi-nodding, lasting a few days, dull coloured (whitish or pinkish and heavily striped with red or purple, unscented. Perianth segments thin-textured, moderately spreading. Dorsal sepal free, subsimilar to the lateral sepals; apex cymbiformLateral sepals subsimilar to the dorsal sepal, attached by their base to the column foot, the protruding basal part on the anterior side fused; apex cymbiform. Petals free, much smaller than the sepals, entireLabellum hinged by a short claw to the apex of the column foot, firmly attached, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina more or less ligulate, three-lobed, thick and fleshy, curved; lateral lobes basal, suberect; margins entire; underside with short papillose hairs; apex entire. Callus obscure, consisting of a shallow basal channel. Nectar present. Column lacking free filament and style, short, straight. Column wings present, ventral and with elongated apical stelidia. Column foot well developed, curved upwards at the apex and thickened. Anther terminal, incumbent, 2-celled, persistent, hinged, smooth or papillate, erostrate. Pollinarium absent. Pollinia 4 in 2 pairs, crescentic, orange, hard, waxy. Viscidium absent. Rostellum ventral, transverse. Stigma entire, vertical, concave. Capsules small, dehiscent, glabrous; peduncle not elongated in fruit; pedicels not elongated in fruit. Seeds numerous, light coloured, winged.

Taxonomy

Fruticicola, previously treated as a section within Bulbophyllum, was recently raised to generic rank (Clements and Jones 2002).

Nomenclature

Fruticicola (Schltr.) M.A.Clem. and D.L.Jones, Orchadian. 13(11): 499 (2002). Type species: Fruticicola albopunctata (Schltr.) M.A.Clem. and D.L.Jones.

Bulbophyllum Thouars sect. Fruticicola Schltr.

Infrageneric Taxa: No infrageneric taxa are currently recognised.

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.

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.

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