Terrestrials or epiliths. Pseudobulbs elongate, usually cylindrical, tapered towards the apex. New pseudobulbs produced annually, anchored by basal roots, each pseudobulb and its leaves lasting one or two years. Leaves relatively broad, thin-textured, plicate. Racemes long, arising from the apex of a current years pseudobulb, the inflorescence developing as the new growth matures. Peduncle ridged longitudinally, with a low wing-like structure on each ridge. Flowers last several days, resupinate, relatively thin-textured, dull-coloured. Perianth segments narrow, with recurved margins, often reflexing or recurving away from the labellum. Labellum much broader than the other segments, reflexing sharply near the middle. Callus consisting of a small basal plate with two conical spur-like calli joined by a low ridge. Column relatively long, narrow, incurved and obscurely winged.
Significant Generic Characters
Size and Distribution
A genus of c.25 species distributed in tropical and warm temperate regions with a concentration in Asia and a few species occurring in Central America and South America. The main part of the genus is disjunctly distributed between China, Japan and New Guinea, northern Australia and New Caledonia. Three endemic species occur in eastern Australia distributed in tropical, subtropical and warm temperate regions, more or less between the McIlwraith Range on Cape York, Queensland (13°46' S) and Lake Cooroibah (26°22' S) in the Wide Bay district. State occurrence: Queensland.
The native species of Diteilis are distributed disjunctly on the east coast from the lowlands to about 800m alt. One species, Diteilis simmondsii, extends from the tropics to warm temperate regions. In the southern parts of its range it is confined to well-drained sandy soils in littoral rainforest, whereas in north-eastern Queensland it grows in highland rainforest. The other native species, Diteilis collinsii, grows among granite boulders in relatively open areas of rainforest. The climate where the tropical species grow has a summer wet season (December to March) with the remaining months being much drier with sporadic or intermittent rain. The plants grow actively during the spring and summer months and are either quiescent (Diteilis simmondsii) or completely leafless and dormant (Diteilis collinsii) for the remainder of the year.
Reproduction: Species of Diteilis reproduce solely from seed. Seed dispersal takes 3-4 months from pollination and the capsules develop in an erect position. There is no elongation of the peduncle or pedicels. Apomixis is unknown in the genus.
Seasonal Growth: Species of Diteilis survive the dry parts of the year as quiescent plants or are completely deciduous, surviving as dormant stems. New growth is produced rapidly after spring or summer rains.
Flowering: The native species of Diteilis flower in autumn, spring and summer.
Hybrids: Neither interspecific or intergeneric hybrids are known involving species of Diteilis.
Fire: The native species of Diteilis grow in habitats that are not highly fire-prone, but plants are generally killed by any fires that occur.
Diteilis is derived from the Greek, dis, di-, double and tilae, tilos, flocks or down, which is obscure [it is believed that Rafinesque actually meant to use dis, di-, double and tylos, a wart, as found in his later name Dituilis, in reference to the two wart-like calli on the labellum base]. This later name has been treated as an orthographic variant.
Perennial, deciduous or evergreen, terrestrial herbs, sympodial. Roots filamentous, produced from the base of a newly maturing pseudobulb. Stems reduced or absent. Pseudobulbs present, emergent, elongate, cylindrical, tapered, fleshy, multiple-noded, each lasting 1-3 seasons. Trichomes absent. Leaves lasting 1-2 seasons, lateral and apical, few per shoot, sheathing at the base, with or without a distinct petiole. Leaf lamina broad, thin, membranaceous, plicate. Venation acrodromus to campylodromus, with few cross-veinlets. Inflorescence racemose, terminal, few to several-flowered, erect, arising with the new growth. Peduncle of similar length to the rhachis, angular (sometimes 4-angled), winged along the ridges, with small, projecting sterile bracts. Floral bracts small, sheathing or free, often white-dotted (? stomata). Ovary elongate, straight or curved, sometimes twisted, ribbed. Flowers resupinate, widely spaced to moderately crowded, dull coloured (yellowish, orange, red or purplish), pedicellate. Dorsal sepal free, narrower than the lateral sepals, often recurved or reflexed, margins revolute. Lateral sepals free, asymmetric, broader than the dorsal sepal, often recurved or reflexed. Petals of similar length to the sepals but much narrower, margins revolute. Labellum fixed by its base to the anterior column base, immoveable, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina entire, usually sharply reflexed back on itself near the middle; margins entire; apex entire, apiculate, emarginate, erose, denticulate or papillate. Spur absent. Callus generally obscure, restricted to the base, consisting of a flat to concave plate with a pair of short, erect, conical, spur-like calli connected by a low ridge. Nectar usually present. Column lacking free filament and style, elongated, incurved distally. Column wings present, mainly apical, often vestigial, ventral, narrow or semi-round. Column foot absent. Pseudospur absent. Anther terminal, 2-celled, persistent, basifixed, porrect, smooth or papillate, rostrate. Pollinarium absent. Pollinia 4 in 2 pairs, hemispherical, yellow or orange, hard, waxy. Viscidium absent. Rostellum ventral, transverse, protruding. Stigma entire, transverse, concave. Capsules dehiscent, glabrous, erect; peduncle not elongated in fruit; pedicels not elongated in fruit. Seeds numerous, light coloured, winged.
Diteilis Raf., Herb. Raf. 73 (1883).