Swamp Orchids
Large evergreen terrestrials, either with crowded fibrous pseudobulbs or long narrow fleshy stems, each with a few large, stalked, pleated leaves. The unbranched inflorescence, which arises from a basal or medial node, carries large white or colourful flowers. The flowers, which open widely, have spreading segments and the basal part of the labellum is fused to the column. The erect lateral lobes incurve over the column to form a tube, the midlobe flares and there is a short spur at the base. The stout column is usually hairy and sometimes has 2 or 3 anthers.
Significant Generic Characters
Evergreen autotrophic terrestrial orchids; pseudobulbs present or replaced by elongate narrow fleshy stems, crowded, multinoded; leaves few per shoot, stalked, pleated, large, often relatively broad; inflorescence racemose, arising from a basal or medial node; flowers stalked, resupinate, white, yellow, brown or red; sepals and petals free; petals smaller than the sepals; labellum fixed to the column base, sometimes also the basal labellum margins fused with the column to form a short tube; lamina usually 3-lobed, rarely unlobed, the lateral lobes incurved over the column to form a tube, with a short basal spur; column without a foot; pollinia 8 in 2 groups of 4, all pollinia subequal, stalked.
Size and Distribution
A genus of about 20 species distributed in Africa, India, China, South-east Asia, Malaysia, Philippines, Indonesia, New Guinea, New Caledonia, Polynesia and Australia where there are 3 species, 2 endemic. State occurrence: Queensland, Northern Territory, New South Wales.
Ecology
Phaius australis and P. australis var. bernaysii grow in moist to wet areas of open forest, seepage sites and swamps and the other species, P. pictus and P. amboinensis, grow in sheltered areas of shady forest, particularly rainforest, in well-drained to wet soil.
Biology
Pollination: Phaius australis and P. australis var. bernaysiiare self-pollinating whereas P. amboinensis and P. pictus appear to be insect-pollinated but the vectors are unknown.
Reproduction: Reproduction in Phaius 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: The native species of Phaius are evergreen and new shoots are produced mainly in spring and summer.
Flowering: The native species of Phaius mainly flower between August to November; Phaius pictus flowers April to June.
Hybrids: Natural hybrids involving the native species of Phaius are unknown.
Fire: The native species of Phaius do not grow in fire-prone habitats.
Derivation
The name Phaius is derived from the Greek phaios, dusky, swarthy, in reference to the mainly brownish colouration of the flowers.
Botanical Description
Perennial geophytic herbs, autotrophic, evergreen, sympodial. Plants glabrous. Flowering and non-flowering plants monomorphic. Pseudobulbs fibrous or woody, emergent, short, multinoded, crowded, lasting several years, sometimes replaced by elongated fleshy stems. Roots fleshy, branched. Trichomes absent or present on some floral parts. Leaves few per shoot, spirally-arranged, much longer than wide but relatively broad, plicate, strongly costate, lasting several seasons, petiolate; base sheathing; lower leaves reduced to imbricate sheathing bracts. Venation unknown. Inflorescence racemose, arising from a basal or medial node, erect, few-many-flowered. Peduncle much longer than the rhachis, with scattered semi-tubular sheathing bracts. Rhachis much shorter than the peduncle, straight, glabrous. Floral bracts small, not sheathing. Pedicel long, thin, merging with the ovary. Ovary straight, elongate, narrow, glabrous. Flowers few-numerous, resupinate, small to large, opening widely, white, yellow, brown or red, lasting few-several days, opening sequentially in a spiral. Dorsal sepal free, subsimilar to the lateral sepals, erect to incurved. Lateral sepals free, subsimilar to the dorsal sepal, divergent. Petals free, smaller than the sepals, spreading. Labellum firmly attached to the base of the column by its base and sometimes also its basal margins to form a short tube, markedly dissimilar in size and shape to the sepals and petals, usually calcarate. Labellum lamina usually 3-lobed, rarely unlobed (Phaius pictus); lateral lobes large, incurved and usually embracing or enclosing the column; midlobe short, flared. Spur basal, short, cylindrical. Callus consisting of keels or narrow flat plates. Nectar present or absent. Column porrect from the end of the ovary, relatively long, straight, glabrous or hairy, lacking free filament and style. Column wings obscure, terminal, sometimes extended and flanking the anther. Column foot absent. Pseudospur absent. Anther terminal, incumbent, 4-celled, glabrous or hairy, rostrate, sometimes 1-2 extra anthers produced. Pollinarium present. Pollinia 8, in 2 groups of 4, all pollinia subequal, clavate, clustered, attached to short caudicles. Viscidium elongate, at an angle to the pollinia, sometimes absent. Rostellum small, sometimes projecting, sometimes vestigial. Stigma entire or with small appendages, concave. Capsules dehiscent, glabrous or hairy, pendulous; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Nomenclature
Phaius Lour., Fl. Cochinch. 517, 529 (1790).
Type species: Phaius grandiflorus Lour.,
Infrageneric Taxa: A genus of 4 sections.
References
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.