Corybas iridescens

Detailed description

Terrestrial, tuberous, glabrous, summer-green herb forming extensive colonies. Tuberoids globose to ellipsoid on extended roots. Leaf solitary, fleshy, more or less subcoriaceous, usually spreading and held flat to the ground surface; shortly petiolate, petiole 3.0–10.0 × 1.5–3.0 mm; lamina 20–40 × 15–35 mm, or larger, ovate-oblong or bluntly wedge-shaped, often pandurate, squared and apiculate at apex, with apiculus decurved, rounded and cordate at base; midrib grooved above, ridged beneath; leaf colour dull dark green above with purple flecks on margins, on midrib, or overall, silvery beneath. Flowers 1–(2), 12–20 mm long, dark red-green, dominated by labellum, dorsal sepal and long filiform petals and lateral sepals; peduncle 4–5 mm long. Ovary 4–8 mm long, green or cream, purple-flecked, curved, subtended by two unequal floral bracts, the smaller 3–5 mm long, linear-subulate, terete the larger equal to or exceeding the ovary, 7–10 mm long, lanceolate, green flecked with purple. Dorsal sepal extending well past labellum 20–35 × 8–12 mm, narrowly ovate in outline when flattened, concave, cucullate and arching over the labellum tube, with apex usually recurved; green spotted and/or striped with purple. Lateral sepals 50–70 × 0.5–1.0 mm at widest point; filiform, greatly exceeding labellum; translucent white with purple striations, horizontal to suberect and projecting forwards and outwards; suberect to erect and spreading; channelled, and twisted. Petals 40–60 × 0.5–1.0 mm at widest point, slightly shorter than lateral sepals, filiform, greatly exceeding labellum, translucent white with purple striations, horizontal to suberect, projecting forwards and outwards; channelled, auriculate on the base of the column. Auricles short, projecting downwards and forwards, with apertures 1.5–2.5 mm across. Labellum conspicuous, dark red, maroon-red to almost black, sometimes striped with green at front, iridescent when wet; labellum tube 5–7 mm long, erect at first then abruptly deflexed through 160–180 degrees, and expanding into the lamina with a prominent bead-like callus in throat of tube at bend; lamina 10–20 × 10–15 mm, broadly ovate to orbicular; upper margins folded inwards, mostly overlapping; lower surface spreading, deflexed against ovary; with margins erose-papillose, and a long median apiculus; inner surface with dense, minute, retrorse papillae and ridged veins; throat of labellum tube high on lamina. Column 3–4 mm long, broadest and ridged at base, inclined backwards, minutely winged. Stigma scutiform to oblong, 1 mm diameter, concave. Anther 1 mm, purple-obtuse. Pollinia 4, united in pairs, 1.0 × 0.7 mm, oblong, mealy, yellow. Capsule 12–20 × 5–7 mm, elliptic, initially pale green later brown, on greatly elongated peduncle.