Clumping epiphytes or lithophytes, rarely terrestrial, the stems either developed into pseudobulbs or thin and elongating from the apex for a few years. Leaves vary from long and narrow to relatively short and very thick, smooth and flat or deeply channelled. Inflorescences are usually long, unbranched and with one to many, small to large flowers. The labellum, which is hinged to the base of the column or apex of the column foot, has large erect lateral lobes, a short projecting midlobe and a ridged or shiny sunken callus. The column is long, narrow, straight or curved, with or without a foot.
Significant Generic Characters
Epiphytic, lithophytic or terrestrial orchids, rarely leafless saprophytes (non-Australian); stems either pseudobulbous or thin and elongating over a number of years, rarely subterranean, multinoded; leaves, when present, sessile, distichous, smooth or appearing plicate, articulated on a persistent leaf base; inflorescence lateral, racemose, 1-many-flowered; flowers small to large, lasting many days; sepals and petals subsimilar; labellum hinged to the base of the column or apex of the column foot, in some species the basal labellum margins fused with the column; lamina 3-lobed; lateral lobes, large, erect; midlobe short, often recurved; callus consisting of keels, ridges or swellings, rarely a glistening depression; column elongate, with or without a foot; pollinia 2 or 4, attached to a viscidium via short caudicles.
Size and Distribution
A genus of about 50 species widely distributed in tropical and subtropical areas of Asia, including China, Japan, India, Thailand, Malaysia, Philippines, Indonesia, New Guinea and Australia where there are 3 endemic species. One native species, Cymbidium canaliculatum, exhibits xerophytic features and is widely distributed in semi-arid areas in northern areas and on the western slopes of the ranges, although it does extend to the coast in some areas. The other 2 species prefer mesic habitats. State occurrence: Western Australia, Northern Territory, Queensland, New South Wales.
Ecology
Cymbidium madidum, grows as a perched epiphyte on the trunks and branches of trees and as a lithophyte on rocks, boulders and cliff faces. In some coastal scrubs it also grows as a terrestrial in sandy or gravelly soil. The other 2 native species, Cymbidium canaliculatum and Cymbidium suave, grow as epiphytes on trees (mainly Eucalyptus and Corymbia spp., less commonly Callitris and paperbarked Melaluca spp.) but their extensive root system penetrates the rotting heartwood of the tree and does not roam over the surface of the bark as do the roots of most epiphytes. These species also form rhizomes which grow through the heartwood and can emerge from limb hollows and fissures in the trunk to eventually form separate plants. Habitats for Cymbidium madidum and Cymbidium suave include rainforest, rainforest margins, wet sclerophyll forest, coastal scrub and moist areas of open forest. Cymbidium suave also colonises rotting logs and decaying stumps, sometimes persisting in open paddocks. Cymbidium canaliculatum is very drought tolerant and commonly occurs in habitats well inland from the coast, including open forest, woodland, tropical savannah, Callitris woodland, Brigalow and vegetation fringing streams. Its drought-tolerant features include thick leathery leaves that are deeply channelled and direct moisture to the base of the plant, an extensive root system that taps moisture reserves in the rotting heartwood of the host, rough leaf epidermis that maintains a boundary layer over the leaf surface and CAM photosynthetic pathways. This adaptable species also extends to coastal districts in some areas and on Melville Island, NT, has been observed growing on bloodwoods overhanging the sea.
Biology
Pollination: The flowers of native Cymbidium species are pollinated by bees of the genus Trigona.
Reproduction: Reproduction in Cymbidium is solely from seed, although Cymbidium canaliculatum and Cymbidium suave exhibit localised vegetative reproduction within their host. Seed dispersal takes about 12 months from pollination and the capsules develop in a pendant position. Apomixis is unknown in the genus.
Seasonal Growth: The native species of Cymbidium mainly grow during spring and summer and are relatively quiescent for the remainder of the year.
Flowering: The native species of Cymbidium flower mainly in spring, sometimes extending to early summer.
Hybrids: Natural hybrids involving the native species of Cymbidium are unknown.
Fire: Plants often grow in fire-prone habitats. Exposed plants are generally destroyed by fire although sometimes they can resprout from less-damaged parts. Cymbidium suave has the ability to reshoot from the base after the emergent parts are destroyed.
Derivation
The name Cymbidium is derived from the Greek kymbes, boat-shaped cup, apparently in reference to the boat-shaped labellum of some species.
Botanical Description
Perennial, leafy, terrestrial, epiphytic, autotrophic herbs, evergreen, rarely leafless mycotrophic herbs (non-Australian), sympodial. Plants glabrous. Roots numerous, short to long, thick, rarely absent Stems mostly swollen and developing as emergent pseudobulbs, sometimes pseudo-monopodial, non-pseudobulbous and elongating for several years (e.g. Cymbidium suave), rarely as elongate tuberculate subterranean stems. Trichomes either absent or present on the labellum. Leaves present or absent, 3-12 per shoot, articulated on the leaf base, distichous, lasting several seasons, flat, either conduplicate and smooth or flat and pseudo-plicate, sessile, sometimes thick and fleshy (Cymbidium canaliculatum); leaf bases persistent, sheathing. Venation unknown. Flowering and non-flowering plants monomorphic. Inflorescence racemose, axillary, 1-multiflowered. Peduncle shorter than the rhachis, with few-several imbricate sterile bracts. Rhachis straight, longer than the peduncle. Floral bracts small, narrow, scarious, partially sheathing the base of the pedicel. Pedicel short, merging with the ovary. Ovary short, straight. Flowers resupinate, small to large, lasting several days, opening sequentially, variously coloured, pedicellate. Perianth segments thin to fleshy, spreading or porrect. Dorsal sepal free, similar to the lateral sepals. Lateral sepals free, similar to the dorsal sepal. Petals free, subsimilar to the sepals, sometimes porrect and flanking the column. Labellum free, either hinged to the column base or the apex of the column foot or partially fused to the base of the column, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina 3-lobed, some species with a short pseudospur formed by the column and basal labellum margins; lateral lobes large, erect; midlobe porrect to recurved. Spur absent. Callus variable, consisting of keels, ridges or swellings, rarely a glistening depression. Nectar absent. Column porrect from the end of the ovary, narrow, elongate, straight or curved, lacking free filament and style, fleshy. Column wings greatly reduced, terminal. Column foot short or absent. Pseudospur present or absent (see labellum lamina). Anther terminal, incumbent, 2-celled, persistent, smooth, with a short rostrum. Pollinarium present. Pollinia either 2, fused along the inner margin or 4 free unequal pollinia, hard, waxy, appearing sessile but attached to the viscidium by short elastic caudicles. Stipe absent. Viscidium large, often triangular. Rostellum small, entire, beaked. Stigma entire, small to large, concave. Capsules dehiscent, glabrous, pendant; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Notes
Cymbidium canaliculatum is widely distributed across northern Australia and extends further inland than any other native epiphytic orchid.
Nomenclature
Cymbidium Sw., Nov. Act. Soc. Sci. Uppsal. 6: 70 (1799). Type species: Cymbidium aloifolium (L.) Sw.
Infrageneric Taxa: A genus of 3 subgenera:-
Subg. Cymbidium Type species: Cymbidium aloifolium (L.) Sw. Labellum free, hinged to the column base or apex of the column foot. A subgenus of 6 sections of which Sect. Austrocymbidium Schltr. contains the Australian species.
Subg. Cyperorchis (Bl.) Seth & Cribb. Type species: Cymbidium elegans Lindl. Labellum base fused with the column base; pollinia 2, fused along the inner margin (non Australian taxa).
Subg. Jensoa (Raf.) Seth & Cribb. Type species: Cymbidium ensifolium (L.) Sw. Pollinia 4, all free (non Australian taxa).
References
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Dockrill, A.W. (1969). Australian Indigenous Orchids. Volume 1. The Society for Growing Australian Plants, Halstead Press, Sydney.
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Du Puy, D. & Cribb, P. (1988). The Genus Cymbidium. Timber Press, Oregon.
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Ross, E.M. and Jones, D. (1989), in Stanley, T.D. & Ross, E.M., Flora of South-eastern Queensland, vol. 3. Queensland Department of Primary Industries.
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Seth, C.J. & Cribb, P.J. (1984). A taxonomic revision of the sectional limits in the genus Cymbidium. In Arditti, J. (ed.), Orchid Biology, Reviews and Perspectives. Cornell University Press, Ithaca & New York, pp. 283-322.
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