Bottlebrush Orchid
Epiphytes or lithophytes with very short indiscernible rhizomes anchored by roots that arise from nodes at the base of the pseudobulb. Pseudobulbs elongated, hard, cane-like, thickened in the middle, nodes irregularly swollen, leafy in the distal half. Pseudobulbs leafy in the first year, then naked. Leaves lasting one season, thin, flat, without any channel or groove, much longer than wide, basally sheathing, apex unequally notched. Racemes short, condensed, arising from the upper nodes of a pseudobulb. Flowers long-lasting, crowded, thick-textured, unscented. Perianth segments very thick and fleshy. Lateral sepal bases fused with the column foot. Sepals and petals of similar length. Petals narrower than the sepals. Labellum stiffly attached to the apex of the column foot. Labellum lamina unlobed, more or less tubular, with a very thick upturned apex and a long basal spur.
Significant Generic Characters
Epiphytic/lithophytic orchids; rhizomes very short, indiscernible; pseudobulbs elongated, cane-like, thickened medially, nodes irregularly swollen, leafy in the distal half; leaves lasting one season, thin, flat, longer than wide, basally sheathing; racemes short, condensed, occurring on distal nodes; flowers long-lasting, crowded; perianth segments thick, fleshy; lateral sepal bases fused with the column foot; sepals and petals of similar length; petals narrower than the sepals; labellum stiffly attached to the apex of the column foot; lamina unlobed, more or less tubular, with a very thick upturned apex and a long basal spur.
Size and Distribution
A monospecific genus distributed in Indonesia, New Guinea and north-eastern Queensland. In Australia, Coelandria smillieae is variously scattered between the Torres Strait islands (9º25' S on Dauan Island) south to near Townsville (19' S). State occurrence: Queensland (including Moa and Dauan Islands).
Ecology
Coelandria smillieae is most abundant in lowland and coastal areas but also extends into the ranges and tablelands at low to moderate altitudes. It grows on trees and rocks in moist but airy habitats. It is especially common on trees in humid areas such as swamp forest, besides streams, estuaries and in mangroves as well as in rainforest, open forest, woodland and coastal scrub. The climate is tropical and the majority of rain falls during the summer wet season (December to March), with the remaining months much drier and having sporadic or intermittent rain.
Biology
Pollination: The flowers of Coelandria smilliae last many days and are pollinated by the Yellow Honeyeater, Lichenostomus flavus, which hovers in front of the inflorescence and inserts its beak into the flower, gathering nectar with its tongue.
Reproduction: Reproduction in Coelandria smilliae is solely from seed. Seed dispersal takes 8-10 months after pollination and the capsules develop in a pendulous 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 in spring.
Hybrids: Natural hybrids involving Coelandria smilliae are unknown.
Derivation
Coelandria is derived from the Greek koilos, hollow and anthera, anther. It refers to the pollinia which are united to form a shallowly cupped unit.
Botanical Description
Perennial, deciduous, epiphytic or lithophytic herbs, sympodial. Plants glabrous. Roots elongate, produced from nodes on the base of the pseudobulb. Rhizome superficial, branched. Pseudobulbs well-developed, crowded, elongate, swollen at the base then with a narrow basal section, increasing in width and swollen near the middle before tapering to the apex, the nodes irregularly swollen, hard, when young covered by scarious or papery bracts. Trichomes absent. Aerial growths occasional, arising from the apical nodes on the pseudobulbs. Leaves lasting one season, distichous, occurring on distal nodes, sessile, longer than wide, flat, not grooved or channelled, thin, smooth; base sheathing the pseudobulb; margins entire; apex unequally emarginate. Inflorescence a condensed raceme, erect, arising from an apical node on a mature pseudobulb, multiflowered. Peduncle much shorter than the rhachis, the base covered with imbricate scarious bracts. Floral bracts scarious, sheathing the base of the pedicel. Pedicel short, thin, merging with the ovary. Ovary short, straight or curved. Flowers non-resupinate, stalked, lasting many days, waxy, cream, white or pink; labellum tubular, with a contrasting dark green apex. Perianth segments very thick and fleshy, slightly spreading, entire, straight. Dorsal sepal free, subsimilar to the lateral sepals; apex entire, flat. Lateral sepals subsimilar to the dorsal sepal, attached by their bases to the column foot; apex entire. Petals free, similar length to the sepals but narrower; apex entire. Labellum stiffly attached to the apex of the column foot (see also spur below), markedly dissimilar in size and shape to the sepals and petals, calcarate. Labellum lamina more or less linear with a swollen apex, fleshy, unlobed; margins entire, thickened, upturned; apex upturned, pouch-like, thickened, dark green, shiny, with incurved margins. Spur present, formed by the fused elongated base of the labellum and elongated apex of the column foot, with an apical transverse septum. Callus apparently absent. Nectar present. Column lacking free filament and style, fleshy, shorter than the perianth segments, straight. Column wings present, reduced, ventral and with short tooth-like apical stelidia. Column foot well developed, longer than the column, straight or recurved. Pseudospur absent. Anther terminal, incumbent, 2-celled, persistent, attached dorsally by a ligulate claw, smooth, with a short decurved rostrum; apex papillate. Pollinarium present. Pollinia 4 in 2 pairs, falcate, brown, hard, waxy. Viscidium short, oblong. Rostellum ventral, swollen, transverse. Stigma entire, vertical, deeply sunken, with ridged margins formed by the column. Capsules dehiscent, glabrous, pendulous; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Taxonomy
This genus, although described as early as 1882, has generally been treated as a synonym of Dendrobium where it has been placed in section Pedilonum. Molecular studies clearly show its relationships with members of that section are tenuous.
Nomenclature
Coelandria Fitzg., Austral. Orch. 1(7): t.2 (1882). Type species: Dendrobium smillieae F.Muell. [Coelandria smillieae (F.Muell.) Fitzg.].
References
Clements, M.A. and Jones, D.L. (2002). Nomenclatural changes in the Dendrobieae (Orchidaceae). 1: The Australasian Region. Orchadian 13(11): 485-492.
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.