Pterostylis silvicultrix

Detailed description

Terrestrial tuberous orchid growing in colonies, sometimes found as a low epiphyte perching on the bases of tree fern trunks. Plants dimorphic. Sterile plants 20–150 mm tall; leaves 30–80 × 10–20 mm, light green, elliptical to elliptical-lanceolate, margins entire or rarely minutely sinuate. Flowering plants with 3–6 cauline leaves obliquely erect to spreading; lamina 40–150 × 0.6–22 mm, elliptical to elliptical-ovate to lanceolate, sessile, sheathing at base; margfins entire; apex acute to acuminate. Pedicel 5–30 mm long, stout. Ovary 10–15 mm long, asymmetric, ribbed. Flower solitary, 18–25 mm long, erect, translucent white and green with red brown suffusions toward the tips of the galea and lateral sepals; galea erect and gibbous at base, then curving forwards to the apex. Dorsal sepal slightly longer than the petals, 20–25 × 10–16 mm ovate-lanceolate, expanded in proximal ⅓ then narrowed and tapered to the acute apex. Lateral sepals erect, loosely embracing the galea leaving a narrow lateral gap to the petal margins, upper part of sinus curved when viewed from the side, sloping to a broad V when viewed from the front; conjoined part 10–15 mm long, 8–10 mm at the top, narrowed to 3 mm wide at the base, the margins inrolled, tapered towards the free points; free points 8–10 mm long curved forwards, tips equal to or protruding slightly above the galea (often curled forward). Petals 25–30 × 4–6 mm, obliquely oblong-lanceolate, falcate, acute, green with a narrow white central area towards the base, the apex reddish-brown; flange vestigial. Labellum erect, curved forward distally,the apex prominent through the sinus in the set position; labellum hinge ligulate 3 × 1 mm; lamina 12–14 mm, green narrow-obovate, callus 0.5–0.7 mm reddish green, raised; appendange 2 mm, decruved, apex penicillate. Column 15 mm, green and white, column foot 4 mm, wings 7 mm; basal lobes 3 × 1 mm, apex obtuse,inner margins incruved, sparsely ciliate; mid-section 3 mm, green; apical lobe 1 mm. Stigma 5 × 1.5–2 mm, elliptic scutiform, medial on the column to edges, raised. Rostellum 0.5 mm diameter, brownish, below anther and high up above stigma and connected to it by a narrow groove. Capsule 25–30 × 6–8 mm, initially green to brown, narrowly obovoid, peduncle up to 50 mm long.