Corybas orbiculatus

Detailed description

Mainly solitary, terrestrial, tuberous, glabrous, winter to spring-green herb. Plant at flowering 30-35 mm tall, erect. 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 2.5–6.0 × 1.5–2.0 mm; lamina 15–25 mm long, generally elliptic-cordate, sometimes somewhat broadly cordate, rarely pandurate, apex rounded and shortly apiculate; midrib grooved above, ridged beneath; leaf colour dull dark green to yellow-green above often with purple flecks on margins, or overall, silvery pellucid beneath. Flower solitary, large for plant 15–20–(25) mm long, dark red-green to reddish-purple; peduncle almost sessile, very short and stout, 1.5–2.0 mm long. Ovary 2.5–5.0 mm long, narrowly oblong to ellipsoid, green, yellow-green, or cream, erect or slightly curving back from leaf; subtended by two unequal floral bracts, the smaller forward projecting toward leaf, 1.5–3.0 mm long, linear-subulate, pale green to cream, terete, the larger equal to or exceeding the ovary, 2.5–6.8 mm long, lanceolate to linear-lanceolate, curved, deeply keeled and closely sheathing ovary for about half of length, apex acute, long, drawn out deeply keeled, green, usually with purple or reddish striae or flecks. Dorsal sepal membranous, 15–20 mm long, more or less equal to labellum length, greenish-purple or purple red striate, or more or less translucent flecked or streaked with purple, lanceolate-acuminate, apex acute, usually recurved away from labellum. Lateral sepals and petals 10–15–(18) mm long, filiform equal to or shorter than dorsal sepal; green, greenish-yellow flecked or striped with purple or maroon, horizontal to suberect or erect, lateral sepals projecting forwards more or less closely embracing labellum; petals projecting forwards and more or less downwards, often touching the leaf. Labellum conspicuous, dark purple-red, maroon to red; labellum tube 3–8 mm long, erect at first then abruptly deflexed 110–130 degrees, and expanding into the lamina; lamina (10)–15–20–(25) × 4–10 mm, narrowly orbicular when flattened, upper margins sharply folded inwards, upper ⅓ more or less overlapping; lower surface spreading, apex usually touching leaf at about ½ leaf length from petiole; margins initially more or less smooth, becoming finely denticulate and then distinctly and broadly deltoid toothed 2–4 times on either side or crenate-denticulate, and with a short median down-curved apiculus.