Butterfly Orchids, Lawyer Orchids
Unbranched or sparsely branched epiphytes or large freely branched lithophytes with fibrous stems and long, relatively broad, thin to thick leaves. Inflorescences are short to long, thin to thick, unbranched with few to many fragrant flowers. They have relatively narrow to broad incurved to spreading segments and a 3-lobed labellum with large lateral lobes that is hinged to the apex of the column foot. The column is short with a relatively long column foot.
Similar Genera
Significant Generic Characters
Small epiphytic or large lithophytic orchids; plants unbranched or sparsely branched (epiphytes) or freely branched (lithophytes); stems thin to thick, fibrous; leaves small to large, crowded, in 2 ranks, longer than wide, thin-textured to thick, leathery; inflorescence racemose; flowers small to moderately large, few to many, lasting several days, opening sequentially or spasmodically; perianth segments narrow to broad, incurved to spreading; sepals and petals subsimilar to dissimilar; petals smaller than sepals; labellum hinged to the apex of the column foot; lamina 3-lobed, without a spur; lateral lobes large, erect, incurved; midlobe small to well-developed, fleshy, resembling a spur, sometimes hairy; column short, with a long foot; pollinia 4, sessile on a stipe, in 2 unequal pairs.
Size and Distribution
A genus of about 19 species, most occurring in Australia with a single species in New Caledonia. In Australia the genus is distributed between the McIlwraith Range on Cape York Peninsula (about 13º34' S) and eastern Tasmania (about 42º10' S). State occurrence: Queensland, New South Wales, Victoria, Tasmania.
Ecology
Species of Sarcochilus grow in a range of habitats from moist and sheltered to quite exposed situations. The smaller types mainly grow as epiphytes, although plants of some species often also occur on rocks. They are found on shrubs and trees in various types of forest, including streamside vegetation, wet sclerophyll forest and rainforest. Rainforests where they grow range from moist to wet humid types in the tropics, subtropics and temperate regions to depauperate rainforest and other dry scrubs in rainshadow areas. The lithophytic species grow on large boulders, cliff faces and gorges, sometimes forming extensive patches. Sarcochilus species are distributed from the coastal lowlands to montane areas in the ranges and tablelands.
Biology
Pollination: The flowers of Sarcochilus last many days and are pollinated by native bees.
Reproduction: Reproduction in Sarcochilus is solely from seed. Seed dispersal takes 10-12 months after pollination and the capsules develop in a porrect position. Apomixis is unknown in the genus.
Seasonal Growth: Plants of Sarcochilus grow mainly during the spring and summer months and are relatively quiescent for the remainder of the year.
Flowering: Sarcochilus species flower between winter and autumn.
Hybrids: Natural hybrids involving Sarcochilus are unknown.
Derivation
Sarcochilus, which is derived from the Greek sarcos, fleshy and cheilos, lip, refers to the fleshy labellum.
Botanical Description
Perennial, evergreen, epiphytic or lithophytic herbs, monopodial. Roots thin or thick, elongate, straight or convolute, adherent. Plants small to large, ranging from sparsely branched (epiphytes) to freely branching and forming extensive clumps (lithophytes). Stem(s) relatively thick, short to moderately long, fibrous. Pseudobulbs absent. Trichomes absent or restricted to the labellum. Leaves lasting several seasons, crowded, distichous, sessile, longer than wide, narrow to broad, mostly flat, thinly coriaceous to thick, smooth or verrucose; base sheathing the stem, persistent after leaf abscission; margins entire, undulate or serrulate; apex unequally emarginate. Venation parallel. Inflorescence lateral, racemose, arcuate to pendulous, multiflowered. Peduncle shorter, equal or longer than the rhachis, thin and wiry to thick and fleshy. Rhachis straight. Floral bracts scarious, sheathing the base of the pedicel. Pedicel short, thin, merging with the ovary. Ovary short, straight. Flowers resupinate, small, stalked, opening sequentially or at spasmodic intervals, lasting several days, variously coloured, often fragrant. Perianth segments thin-textured, spreading or incurved, narrowest proximally. Dorsal sepal free, subsimilar to the lateral sepals. Lateral sepals subsimilar to the dorsal sepal, the bases joined to the column foot, flanking the labellum. Petals free, smaller than the sepals. Labellum hinged to the apex of the column foot, markedly dissimilar in size and shape to the sepals and petals, ecalcarate. Labellum lamina fleshy, 3-lobed; lateral lobes large, erect, often incurved; midlobe vestigial to well-developed, mostly solid and fleshy, resembling an apical spur, in the Sarcochilus ceciliae group however it is erect, hairy and partially connate with the lateral lobes. Spur absent. Callus variable, digitiform, plate-like, anvil-shaped, grooved, vestigial or absent. Nectar unknown. Column short, porrect from the apex of the ovary, lacking free filament and style, fleshy. Column wings obscure or absent. Column foot relatively long, at right angles to the column. Pseudospur absent. Anther terminal, incumbent, 2-celled, persistent, smooth, with a short to long rostrum. Pollinarium present. Pollinia 4 in 2 unequal pairs, orange, hard, waxy, sessile. Stipe well-developed, elongate, narrow to broad. Viscidium small to large, at an angle to the stipe. Rostellum small, almost vestigial in some species. Stigma large, entire, concave. Capsules dehiscent, glabrous, porrect; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Taxonomy
Within the Vandeae, Sarcochilus is characterised by hinged 3-lobed labellum without a spur; large lateral lobes; fleshy midlobe resembling an apical spur; short column with a long foot and, 4 stalked pollinia in 2 unequal pairs.
Notes
A distinctive group of 5 or 6 species within the genus has narrow fleshy leaves, thin wiry racemes, small cupped flowers that open spasmodically and an erect thickened labellum midlobe adorned with glandular trichomes.
Nomenclature
Sarcochilus R.Br., Prodr. 332 (1810). Type species: Sarcochilus falcatus R.Br.
Gunnia Lindl., in Edwards’s, Bot. Reg. 20: subt. 1699 (1834). Type species: Gunnia australis Lindl. [Sarcochilus australis Lindl.) H.G.Reichb.
Parasarcochilus Dockr., Austral. Sarcanth. 22 (1967). Type species: Sarcochilus spathulatus R.S.Rogers [Parasarcochilus spathulatus (R.S.Rogers) Dockr.].
Infrageneric Taxa: No infrageneric taxa are currently recognised.
References
Dockrill, A.W. (1967). Australasian Sarcanthinae. The Australasian Native Orchid Society, Sydney.
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.