Coarse epiphytes with thin cylindrical smooth roots, a short projecting fibrous stem and broad, spreading to partly drooping fleshy leaves. Inflorescences are long, thin, unbranched with numerous, small, round, heavily blotched flowers that only last a few hours. They have a 3-lobed labellum that is hinged to the apex of the column foot. The column is short with a relatively long column foot that is attached at a sharp angle to the column.
Similar Genera
Significant Generic Characters
Epiphytic/lithophytic orchids; roots thin, round in cross-section, smooth; plants moderately large; stems short, thick, fibrous; leaves large, often partly drooping, fleshy, in 2 ranks, longer than wide; inflorescence racemose; flowers small, numerous, lasting a few hours; perianth segments thin-textured; sepals and petals subsimilar; labellum relatively small, hinged to the apex of the column foot; lamina 3-lobed, without a spur; lateral lobes large, incurved; midlobe well-developed, hollow; column short, with a long foot at a sharp angle to the column; pollinia 4, sessile on a stipe, in 2 subequal pairs.
Size and Distribution
Currently monospecific with the single species, Rhinerrhizopsis moorei, occurring in eastern Australia and distributed between the Iron Range (about 17º16' S) and the McIlwraith Range (about 32º56' S) on Cape York Peninsula in northeastern Queensland. State occurrence: Queensland.
Ecology
Rhinerrhizopsis moorei grows on shrubs, trees and rocks in rainforest, streamside vegetation, humid areas of open forest, moist gullies and gorges.
Biology
Pollination: The flowers of Rhinerrhizopsis moorei last a few hours and are produced in spasms, usually all the plants in an area flowering simultaneously. They are pollinated by small native bees.
Reproduction: Reproduction in Rhinerrhizopsis moorei 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 Rhinerrhizopsis moorei grow mainly during the spring and summer months and are relatively quiescent for the remainder of the year.
Flowering: Rhinerrhizopsis moorei flowers in winter and spring.
Hybrids: Natural hybrids involving Rhinerrhizopsis moorei are unknown.
Derivation
Rhinerrhizopsis is a genus which has a resemblance to Rhinerrhiza and has previously included in it (-opsis, resemblance).
Botanical Description
Perennial, evergreen, epiphytic or lithophytic herbs, monopodial. Roots thin, smooth, round in cross-section, adherent. Plants unbranched or sparsely branched, moderately large, porrect. Stem short, relatively thick, fibrous. Pseudobulbs absent. Trichomes absent. Leaves lasting several seasons, crowded, distichous, spreading to drooping, sessile, longer than wide, flat, fleshy, smooth; base sheathing the stem, persistent after leaf abscission, imbricate; margins entire; apex unequally emarginate. Venation unknown. Inflorescence lateral, racemose, arcuate to pendulous, multiflowered. Peduncle much shorter than the rhachis, thin, wiry. 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 in spasms along the rhachis, lasting a few hours, yellow to orange with red markings, fragrant. Perianth segments spathulate, thin-textured, incurved to spreading. Dorsal sepal free, subsimilar to the lateral sepals. Lateral sepals free, subsimilar to the dorsal sepal. 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 3-lobed, held forward of the column; lateral lobes large, erect, incurved distally and overlapping; midlobe well-developed, calceiform, conical, hollow, broad, blunt, with a thickened apical lobule. Spur absent. Callus central, fleshy, lobed, the base of each lobe attached to the base of a labellum lateral lobe. Nectar unknown. Column short, porrect from the apex of the ovary, lacking free filament and style, fleshy. Column wings vestigial or absent. Column foot long, at a sharp angle to the column. Pseudospur absent. Anther terminal, incumbent, 2-celled, persistent, smooth, with a short broad rostrum. Pollinarium present. Pollinia 4 in 2 appressed pairs, subequal, orange, hard, waxy, sessile. Stipe short, narrow. Viscidium broad, at an angle to the stipe. Rostellum narrow, decurved. Stigma large, concave. Capsules dehiscent, glabrous, porrect; peduncle not elongated in fruit; pedicel not elongated in fruit. Seeds numerous, light coloured, winged.
Taxonomy
Within the Vandeae, Rhinerrhizopsis is characterised by fleshy, smooth leaves; hinged, 3-lobed labellum without a spur; fugacious flowers with short spathulate tepals; large incurved lateral lobes; well-developed hollow midlobe; lobed callus, the lobes attached to the base of the lateral lobes; short column with a sharply angled foot and, 4 sessile pollinia in 2 subequal pairs.
Nomenclature
Rhinerrhiza P.Ormerod, Oasis, Suppl. 1:2 (2001).
Type species: Thrixspermum moorei Rchb.f. [Rhinerrhizopsis moorei (Rchb.f.) P.Ormerod].
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.