Common name: Large Veined Sun Orchid
Thelymitra venosa R.Br. APNI*
Description: Terrestrial herb.
Leaf linear, to 30 cm long and 7 mm wide, thick to fleshy.
Inflorescence to 70 cm high, 1–6-flowered; flowers open on dull days and do not close at night. Perianth segments to 25 mm long and 12 mm wide, sepals longer than lateral petals, bright blue with darker veins or rarely white to pink or greenish blue. Labellum obovate, blunt and usually broader than other segments. Column to 8 mm long, erect, white. Midlobe short or obscure, with a few papillae. Lateral arms flat, not lobed at apex, spirally twisted or tightly coiled. Anther prominent with pointed apex.
Capsules obovoid, 15–20 mm long, 5–9 mm wide, erect, ribbed.
Flowering: Flowers October to January.
Distribution and occurrence: Grows on wet exposed sandstone ledges or soaks, often in damp clumps of cushion mosses or among low vegetation; confined to Hawkesbury Sandstone, chiefly in the Blue Mtns and adjacent coastal districts.
NSW subdivisions: CC, NT, CT, ST
Rare and of very limited distribution. Suggest 2RC by criteria of Briggs and Leigh (1996) and Near Threatened (NT) by criteria of IUCN (2011). Thelymitra venosa is closely related to T. cyanea (mostly from high altitude parts of south-eastern Australia and New Zealand), but the latter has generally fewer, smaller flowers and the lateral lobes have fewer, looser twists and lobed apices. The ease with which the flowers of T. venosa open, and their propensity to stay open at night, are unusual for the genus.
Text by P. Bernhardt; additional information added Louisa Murray (May 2013)
Taxon concept: Flora of NSW 4 (1993); Jeanes J.A. (2012) Muelleria 30(1): 8–22
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.