Evergreen terrestrials with crowded fleshy pseudobulbs each with a few strongly ribbed, stalked, pleated leaves. The unbranched inflorescence, which arises from a basal node, carries colourful flowers in a terminal group. The flowers, which usually open widely with spreading segments, have the labellum firmly fixed to the apex of the short column foot. In most species the labellum is 3-lobed with prominent lateral lobes and the midlobe has a narrow base and a broadly expanded blade.
Significant Generic Characters
Evergreen autotrophic terrestrial orchids; pseudobulbs crowded, multinoded, emergent; leaves few per shoot, stalked, pleated, the blade articulate on the apex of the petiole; inflorescence racemose, arising from a basal node, glabrous or hairy; flowers in a terminal group, stalked, resupinate, white, yellow, pink or purple; sepals and petals free; labellum fixed to the apex of the column foot, usually 3-lobed; midlobe narrow at the base with an expanded lamina; pollinia 8 in 2 groups of 4, all pollinia unequal.
Size and Distribution
A genus of about 45 species distributed in tropical parts of India, South-east Asia, Malaysia, Philippines, Indonesia, New Guinea, New Caledonia, Polynesia and Australia where there are 2 species distributed in northern tropical areas, 1 species, Spatholglottis paulinae, is endemic. State occurrence: Queensland, Northern Territory.
Ecology
Species of Spathoglottis grow in moist to wet situations in open forest, grassland and in swamps, usually in bright sunny situations.
Biology
Pollination: Spathoglottis paulinae is usually self-pollinating but insect-pollinated variants also occur. Spathoglottis plicata is pollinated by insects but details of the vector(s) are unknown.
Reproduction: Reproduction in the native species of Spathoglottis is mainly from seed although occasional plants produce vegetative bulbils from the nodes on the upper parts of the pseudobulbs and new plants can develop from these structures. Seed dispersal takes 1-2 months from pollination and the capsules develop in a nodding position. Apomixis is unknown in the genus.
Seasonal Growth: The native species of Spathoglottis are evergreen but in extended dry periods, plants of Spathoglottis paulinae can shed their leaves. New shoots are produced mainly in the summer wet season.
Flowering: The native species of Spathoglottis flower between July and April.
Hybrids: Natural hybrids are unknown between the native species of Spathoglottis.
Fire: The habitat where the native species of Spathoglottis grow is usually too wet to burn. If fire does occur the plants will usually be destroyed.
Derivation
The name Spathoglottis is derived from the Greek spathe, spathe, and glotta, tongue, a probable reference to the broad labellum midlobe.
Botanical Description
Perennial geophytic herbs, autotrophic, evergreen or facultatively deciduous, sympodial. Plants glabrous or hairy. Flowering and non-flowering plants monomorphic. Pseudobulbs fleshy, emergent, fibrous, multinoded, crowded, lasting several years. Roots filamentous, wiry, branched. Trichomes present or absent. Leaves few per shoot, spirally arranged, much longer than wide, plicate, strongly costate, usually lasting several seasons, petiolate, articulate on the apex of the petiole; base sheathing; lower leaves often reduced to imbricate sheathing bracts. Venation unknown. Inflorescence an axillary raceme from a basal node, erect, few-many-flowered. Peduncle much longer than the rhachis, with scattered tubular sheathing bracts. Rhachis much shorter than the peduncle, straight, glabrous or hairy. Floral bracts small to large, not sheathing, often deflexed. Pedicel long, thin, distinct from the ovary. Ovary straight, elongate, narrow, glabrous or hairy. Flowers numerous, resupinate, usually crowded, cleistogamous or opening widely, white, yellow, pink or purple, lasting 1-few 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, porrect to divergent. Petals free, subsimilar to the sepals, generally slightly smaller. Labellum fixed to the apex of the column foot, sessile, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina usually 3-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 broad lamina. Spur absent. Callus consisting of 2 raised calli, separate or fused, situated on the narrow basal part of the midlobe, often subtended by expanded curved labellum margins. Nectar absent. Column at an angle to the ovary, elongate, shallowly curved, lacking free filament and style. Column wings absent or obscure. Column foot short or vestigial. Pseudospur absent. Anther terminal, incumbent, 8-celled, shortly rostrate. Pollinaria 2. Pollinia 8, in 2 groups of 4, all 4 pollinia unequal in size, falcate, clavate, narrowed and ending in short caudicles. Viscidium absent. Rostellum narrow, projecting. Stigma entire, convex. Capsules dehiscent, glabrous or hairy, porrect to pendulous; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Notes
The flowers of Spathoglottis species are arranged in a terminal cluster on the peduncle. After pollination the capsules develop quickly and buds, flowers and fruit can be present simultaneously.
Nomenclature
Spathoglottis Blume, Bijdr., 6: t.2, fig.76, 8: 400 (1825). Type species: Spathoglottis plicata Blume.
Paxtonia Lindl. in Edwards’s, Bot Reg. 24 Misc. 61 (1838). Type species: Paxtonia rosea Lindl.
Infrageneric Taxa: No infrageneric treatment of Spathoglottis is currently available.
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.