Common name: Elegant Greenhood
Pterostylis elegans D.L.Jones APNI*
Synonyms: Diplodium elegans (D.L.Jones) D.L.Jones & M.A.Clem. APNI*
Description: Terrestrial herb.
Flowering and non-flowering plants dimorphic. Rosettes borne by non-flowering plants only, leaves 2–4, lamina ovate, 10–20 mm long by 8–13 mm wide, bright green, margins entire, apex subacute; petioles 4–10 mm long.
Scape 15–28 cm tall, slender, smooth; stem leaves 4 or 5, obliquely spreading, lanceolate, 8–25 mm long by 3.0–4.5 mm wide, margins entire, apex acuminate. Ovary 9–12 mm long, green, smooth. Flower solitary, 14–18 mm long by 6–8 mm wide, erect, translucent white with dark green suffusions and stripes, reddish brown toward the apex of the galea and petals. Dorsal sepal 25–30 mm long by 8–10 mm wide, prominently inflated at the base the tapered; filiform point 4–8 mm long. Lateral sepals erect, tightly embracing the galea; sinus with a low, inclined knee when viewed from the side, viewed from the front sloping inwards at a shallow angle, deeply notched medially, folded internally, conjoined part 8–11 mm long by 8–9 mm wide, narrowed to c. 2 mm across at the base; upper margins inrolled, gradually tapered into the free points; free points 14–18 mm long, filiform, erect or slightly recurved, held high aboe the galea. Petals obliquely oblong-lanceolate, 20–25 mm long by 4–5 mm wide, slightly dilated distally; margins entire or slightly irregular, apex acute; flange deltoid, c. 1 mm wide, broadly obtuse. Labellum erect , sharply curved forwards in the distal third, mostly dark red-brown to blackish brown, greenish towards the base, distal half protruding prominently from the sinus in the set position; claw c. 1.5 mm long and 1.2 mm wide; lamina narrowly oblong to oblong-lanceolate, 8–11 mm long by 2.0–2.5 mm wide, slightly constricted in the distal half, apex obtuse; basal appendage linear, 2–3 mm long, curved at right angles near the middle; apex penicillate. Callus c. 0.6 mm across, raised, expanding to c. 0.8 mm across near the apex, dark red-brown throughout.
Distribution and occurrence: Northern Tablelands of New South Wales, from Barrington Tops north to Walcha.
On moist, sheltered sloes in moderately dense tall open sclerophyll forest, between 950 and 1200 m elelvation.
NSW subdivisions: NT
Threatened species: NSW BCA: Vulnerable
Pterostylis elegans is similar to P. decurva but differs by its long-protruding labellum, which may form an exposed horizontal platform beneath the galea; by the shallower knee, whose internal angle is nearly a right angle, and whose upper side is only around 30 degrees offset from vertictal; and the smaller flowers which are 14–18 mm long. The contrasting states in P. decurva are labellum short protruding, and inclined throughout in the set position; the sharp knee, whose internal angle is close to 70 degrees and whose upper side is, or is nearly, horizontal, and whose flowers are 20-25 mm long. Some individuals, including from south of the known range of P. elegans exhibit characteristics intermediate between P. elegans and P. decurva, and may be difficult to place. Pterostylis elegans is similar to P. metcalfei, but differs in the relative length of the labellum and column, equal in P. elegans but labellum longer in P. metcalfei, and in how pronounced the sinus knee is, right angled with upper margin inclined at 45 degrees in P. elegans, or 45 degree internal angle and upper margin nearly level in P. metcalfei.Pterostylis elegans could be confused with P. divaricata but has a distinct knee beneath the sinus, whereas P. divaricata does not. Pterostylis elegans could be confused with P. aestiva, but has smaller flowers (18 mm versus 30 mm long) and the labellum is at most horizontal, it does not curve right through and beyond the horizontal, when set sitting nearly paralell with the sinus margin in side view.
Text by Matt A.M. Renner (9 Dec 2019) based on Jones (1997)
Taxon concept: Jones DL (1997) Six new species of Pterostylis R.Br. (Orchidaceae) from Australia. The Orchadian 12: 245–258.
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