Pterostylis agathicola

Detailed description

Terrestrial tuberous herb growing as solitary plants or in diffuse colonies. Plants dimorphic. Sterile plants 60–100 mm tall; 2–3-leaved; leaves narrowly linear-lanceolate, 30–60 × 3–6 mm, dark green, entire, acute to acuminate. Flowering plants 100–350 mm tall, stems green or pale green, rarely reddish. Leaves 3–4, cauline, widely spaced, spreading; lamina narrowly lanceolate, 40–100 × 5–8 mm, dark green or pale green, sessile, sheathing at base; midrib prominent; margins entire; apex acuminate. Pedicels 10 mm long, slender. Ovary 9–12 mm long, ribbed. Flowers 1–(2), 24–28 mm long, erect or slightly leaning forwards, translucent white and dark green with red brown suffusions at the apex of the galea and lateral sepals; galea gibbous at the base then erect before bending forwards, the apex flat, erect or decurved, the dorsal sepal much longer than the petals. Dorsal sepal ovate-lanceolate in outline when flattened, 33–37 × 12–16 mm, prominent expanded near the base then tapered to the long-acuminate apex. Lateral sepals erect, loosely embracing the galea leaving a prominent lateral gap to the petal margins; upper part of sinus flat or shallowly mounded when viewed from the side, with a deep narrow, central notch when viewed from the front; conjoined part 8–11 × 6–9 mm, narrowed to c. 2.5 mm wide at the base, tapered into the free points; free points 20–26 mm long, tapered, erect, the tips extending high above the galea. Petals obliquely linear-lanceolate, 17–22 × 3–4 mm, strongly falcate, acuminate, green with white stripes, red-brown towards the apex. Labellum erect, curved forwards in the distal ⅓, the apex twisted strongly to the right and protruding prominently through the sinus in the set position; labellum hinge ligulate 3 × 2 mm; lamina narrowly ovate-lanceolate to elliptical lanceolate, 9.0–11.0 × 3.0–3.3 mm, dark green to brownish with a darker reddish central callus, apex subobtuse to slightly emarginate; callus 0.6 mm wide near apex, raised; basal appendage 2.5–3.0 mm long, decurved, apex penicillate. Column 12–14 mm long, bent away from the ovary at 45 degrees at the base then erect, green and white; column foot 4 mm long. Column wings 5–6 mm long; basal lobe 3 × 1 mm, at an angle of about 35 degrees. apex obtuse, inner margins incurved, sparsely and shortly ciliate; mid-section 2.5 mm long; green; apical lobe 1 mm long, linear, obtuse. Stigma scutiform 3.0–3.5 × 2.0 mm, medial on the column, raised. Anther 1.8 mm long, very shortly rostrate. Pollinia linear-falcate, 1.3–1.4 mm long, yellow, mealy. Capsules narrowly-ellipsoid, 20–24 × 5–7 mm.