Common name: Horned Greenhood
Pterostylis bicornis D.L.Jones & M.A.Clem. APNI*
Synonyms: Petrorchis bicornis (D.L.Jones & M.A.Clem.) D.L.Jones & M.A.Clem. APNI*
Description: Small slender perennial with a rosette produced on a separate growth, arising from the base of the floral scape.
Leaves 3–7, in a rosette, cordate, 3–7 mm long, 3–5 mm wide; petioles broad 2–4 mm long.
Inflorescence of 1 or 2 terminal flowers on a very slender scape, 6–10 cm tall. Bracts 10 mm long, 3 mm wide, lanceolate, acuminate, sheathing at the base. Flowers 8–10 mm long, dark green and white; dorsal sepal 6–8 mm long, galeate, erect at the base then curved in the distal third, apex truncate or emarginate. Lateral sepals c. 6 mm long, the free segments embracing the galea and barely exceeding it, the lateral margins covering the petals. Petals 6–7 mm long, curved, the apex formed into a filifrom or slightly clavate tail, 4–5 mm long, which far exceeds the dorsal sepal. Labellum 3.4–4 mm long , 1 mm wide, oblong, with basal appendange shortly branched. Column 3.5–4.5 mm long, erect, slender, wings c. 1.5 mm long, their upper margin produced into a filiform point, the lower margins obtuse, sparsely ciliate. Anther cap c. 0.8 mm long, obtuse, with a very short rostrum. Stigma c. 1 mm x 0.5 mm, cordate, basal, the upper margins irregular. Pollinia (pollen body) c. 0.8 mm long, linear, mealy.
Fruits not seen.
Flowering: Flowers in June and July.
Distribution and occurrence: There is only one location for Pterostylis bicornis currently known in NSW, from near Woodenbong, in far northern NSW. Pterostylis bicornis also occurs in Queensland, at three locations along the NSW - Queensland border. In NSW, Pterostylis bicornis is very highly restricted.
Pterostylis bicornis occurs in heathy forests or in heathlands. It grows in quite specific and limited habitat, in small humus pockets among moss and lichens in very shallow to skeletal soils over rock.
NSW subdivisions: NC
Threatened species: NSW BCA: Endangered; Commonwealth EPBC: Vulnerable
Pterostylis bicornis has affinities with both Pterostylis aphylla and Pterostylis parviflora but can be distinguished readily from these by the filiform tips on the petals. It reproduces both sexually via seed and asexually, by forming tubers along the root system.
Text by Louisa Murray
Taxon concept: Jones, D.L. and Clements, M.A. (1987)
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.