Evergreen terrestrials with crowded fibrous or woody pseudobulbs each with a few stalked, pleated leaves. The unbranched inflorescence, which arises from a basal node, carries white to colourful flowers in a terminal group. The flowers, which open widely with spreading segments, have the basal part of the labellum fused to the margins of the column to form a tubular opening to the spur. In most species the labellum is 3-4-lobed with prominent lateral lobes, a deeply divided midlobe and a short to long basal spur.
Significant Generic Characters
Evergreen or deciduous(non-Australian) autotrophic terrestrial orchids; pseudobulbs crowded, multinoded, fibrous to woody, emergent; leaves 1 (non-Australian) -few per shoot, stalked, pleated, articulate on the base of the petiole; inflorescence racemose, arising from a basal node, glabrous or hairy; flowers in a terminal group, stalked, resupinate, white (Australian), yellow, pink or red; sepals and petals free; labellum claw margins fused with the column margins to form a short tube at the opening to the spur; lamina usually 3-4-lobed, with a short to long basal spur; column without a foot; pollinia 8 in 2 groups of 4, all pollinia subequal, sessile.
Size and Distribution
A genus of about 150 species distributed in Africa, India, South-east Asia, Malaysia, Philippines, Indonesia, New Guinea, New Caledonia, Polynesia and Australia where there is a single endemic species, Calanthe australasica, distributed between the Iron Range on Cape York Peninsula in northeastern Queensland and Termeil in southern New South Wales. State occurrence: Queensland, New South Wales (including Lord Howe Island).
The native species of Calanthe grows in moist shady forest, particularly rainforest. Plants grow in loamy soil on sheltered slopes and near streams, on rotting logs and in accumulations of litter on large boulders.
Pollination: Calanthe australasica is insect-pollinated, probably by hovering moths visiting during the late afternoon or evening.
Reproduction: Reproduction in Calanthe australasica is solely from seed. Seed dispersal takes 6-10 months from pollination and the capsules develop in a nodding position. Apomixis is unknown in the genus.
Seasonal Growth: Calanthe australasica is evergreen and new shoots are produced mainly in spring and summer.
Flowering: Calanthe australasica flowers between October and March.
Hybrids: Natural hybrids involving Calanthe australasica are unknown.
Fire: The habitat where Calanthe australasica grows is usually too wet to burn.
The name Calanthe is derived from the Greek calos, beautiful, and anthos, flower, in reference to the attractive flowers.
Perennial geophytic herbs, autotrophic, evergreen or deciduous (non-Australian), sympodial. Plants glabrous. Flowering and non-flowering plants monomorphic. Pseudobulbs fibrous or woody, emergent, short to elongate, multinoded, crowded, lasting several years. Roots filamentous, fleshy, branched. Trichomes absent. Leaves 1(non-Australian)-few per shoot, spirally -arranged, much longer than wide but relatively broad, plicate, strongly costate, lasting 1-several seasons, petiolate, sometimes narrow and grass-like (non Australian); base sheathing; lower leaves reduced to imbricate sheathing bracts. Venation unknown. Inflorescence racemose, arising from a basal node, erect, few-many-flowered. Peduncle much longer than the rhachis, with scattered semi-tubular sheathing bracts, these either small and persistent or large and deciduous. Rhachis much shorter than the peduncle, straight, glabrous or hairy. Floral bracts small to large, not sheathing, sometimes ephemeral. Pedicel long, thin, merging with the ovary. Ovary straight, elongate, narrow, glabrous or hairy, sometimes at an angle to the ovary. Flowers few-numerous, resupinate, small to moderately large, opening widely, white (Australian), yellow, pink or red, lasting 1-few days, opening sequentially in a spiral. Dorsal sepal free, subsimilar to the lateral sepals, erect to incurved (non-Australian). Lateral sepals free, subsimilar to the dorsal sepal, porrect to divergent. Petals free, smaller than the sepals, porrect to spreading. Labellum stalked, the basal margins of the claw fused with the column margins to form a tube, markedly dissimilar in size and shape to the sepals and petals, usually calcarate, rarely ecalcarate. Labellum lamina usually 3-4-lobed, rarely unlobed (non-Australian); lateral lobes small to large, narrow, incurved to widely divergent, confined to the proximal part of the labellum; midlobe with a narrow basal part, distally expanded into a lamina, entire, emarginate or lobed. Spur usually present, short to long, cylindrical, usually curved, its orifice at the base of the column. Callus consisting of keels (non-Australian) or raised calli, separate or fused, usually on the junction of the labellum claw and lateral lobes. Nectar present. Column porrect from the end of the ovary, relatively short, straight, lacking free filament and style. Column wings absent or obscure (non-Australian). Column foot absent. Pseudospur absent. Anther terminal, incumbent, 4-celled, rostrate. Pollinarium present. Pollinia 8, in 2 groups of 4, all pollinia subequal, clavate, clustered, sessile. Viscidia elongate, at an angle to the pollinia. Rostellum large, deeply bifid, the arms sometimes projecting. Stigma entire or in 2 parts, 1 lobe on each side of the spur orifice. Capsules dehiscent, glabrous or hairy (non-Australian), pendulous; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
The native species was for many years included with the widespread species Calanthe triplicata (Willemet) Ames. A detailed study of the type specimens of Calanthe triplicata together with the types, descriptions and photographs of all species included as synonyms of Calanthe triplicata throughout its range reveal that the Australian species is endemic.
The flowers of Calanthe species are arranged in a relatively crowded terminal cluster on the peduncle. The native species is evergreen whereas some frequently cultivated Asian species are deciduous and flower when the plants are leafless.
Calanthe R.Br. in Edwards’s, Bot. Reg. 7: sub.t. 573 (1821) (nom. cons.).
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.