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Pterostylis ventricosa (D.L.Jones) G.N.Backh.
Family Orchidaceae
Pterostylis ventricosa (D.L.Jones) G.N.Backh. APNI*

Synonyms: Speculantha ventricosa D.L.Jones APNI*

Description: Terrestrial herb.

Rosette leaves spreading, 4–9 per rosette; lamina ovate to sagittate, 3–12 mm long by 3–6 mm wide, dull green; margins entire; apex acute to apiculate; petioles 3–8 mm long, very slender, narrowly winged.

Flowering stem 8–30 cm tall, not elongating in fruit. Scape slender, wiry, 1–6 flowered. Sterile bracts closely sheathing, ovate, 3–6 mm long by 2–4 mm wide, acuminate. Flowers well-spaced, 1–3 open at once, 10–13 mm long by 4.5–5.5 mm wide, green and white towards the base, bright red-brown distally, somewhat shiny, swollen at the base and narrowing distally; galea strongly inflated at base, erect before curving forwards in a semi-circle; petals longer than the dorsal sepal, smooth. Dorsal sepal broadly ovate-lanceolate when flattened, 13–16 mm long by 5–8 mm wide, inflated at the base then tapered to apex, boldly striped, acute to apiculate, smooth. Lateral sepals erect, closely embracing the galea; sinus curved smoothly inwards, the area below bulging when viewed from the side, deeply notched at the centre, margins sloping obliquely upwards; conjoined part 6–8 mm long by 5–7 mm wide, narrowed to 2 mm wide at the base; free points erect, 2.5–3.5 long, tapering, extending beyond top of the galea. Petals broadly oblong, 10–13 mm long y 2.5–3.0 mm wide, falcate, dark brown striped with white, acute; flange c. 1 mm across, broadly triangular, obtuse. Labellum erect, when set the tip visible through the sinus, curved forwards near the apex, dark red-brown and white. Labellum lamina broadly oblong-elliptic, 4.5–5.0 mm long by 2.0–2.5 mm wide, obtuse; basal appendage decurved, c. 1.3 mm long, broadest at the base; apex trifid, erect; callus a raised, central, dark red-brown ridge around 0.3 mm wide.

Capsules erect, obovoid to ellipsoid, 9–12 mm long by 3–4 mm wide.

Photo Lachlan Copeland

Photo Lachlan Copeland

Photo Lachlan Copeland

Flowering: March to May

Distribution and occurrence: Known primarily in the vicinity of Jervis Bay, also observed near Tallong.

Open areas within tall forest dominated by Corymbia gummifera, Eucalyptus pilularis, and E. piperita with a dense heathy understorey, in grey silty loams. Also on roadside verges and other disturbed sites.
NSW subdivisions: SC, CT

Threatened species: NSW BCA: Critically Endangered
AVH map***

Pterostylis ventricosa has a smooth, unornamented, galea hood – a feature that immediately distinguishes it from taxa in the P. parviflora complex having papillae on the galea hood. Pterostylis ventricosa is similar to P. antennifera and P. parviflora but has larger flowers, 10-13 mm long in P. ventricosa, 7–9 mm long in P. antennifera, and smaller again in P. parviflora (Jones 2015).

Text by Matt A.M. Renner (23 Jan 2020) based on Jones (2008); edit A.E. Orme 25 Mar 2020;
Taxon concept: Jones DL (2008) Two threatened new species of Speculantha (Orchidaceae) from south-eastern Australia. The Orchadian 16: 30–35. Jones DL (2015) Five new species of Speculantha (Orchidaceae: Pterostylidinae), from eastern Australia. Australian Orchid Review 80: 41–55.

APNI* Provides a link to the Australian Plant Name Index (hosted by the Australian National Botanic Gardens) for comprehensive bibliographic data
***The AVH map option provides a detailed interactive Australia wide distribution map drawn from collections held by all major Australian herbaria participating in the Australian Virtual Herbarium project.
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