Pterostylis angulata

Pterostylis angulata
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Orchidoideae
Tribe:	Cranichideae
Genus:	Pterostylis
Species:	P. angulata
Binomial name
Pterostylis angulata (D.L.Jones & C.J.French) D.L.Jones & C.J.French[1]
Synonyms[1]
Diplodium angulatum D.L.Jones & C.J.French Pterostylis aff. nana Pterostylis angulata D.L.Jones & C.J.French nom. inval. Pterostylis sp. 'Helena River' Pterostylis sp. 'limestone' Pterostylis sp. 'Helena River' (G.Brockman GBB 340) WA Herbarium Pterostylis sp. 'limestone' (B.J.Keighery & G.J.Keighery 65)

Pterostylis angulata, commonly known as the Helena River snail orchid or limestone snail orchid, is a species of greenhood orchid endemic to south-western Australia.[2][3][4]

Description

Pterostylis angulata is a herbaceous terrestrial orchid with a basal rosette of 4-7 ovate leaves, dark blue-green in colour, each measuring 5–20 mm (0.20–0.79 in) long and 3–12 mm (0.12–0.47 in) wide. This rosette is present on both flowering and non-flowering plants. When flowering, this species produces a single flower on a stalk measuring 70–180 mm (2.8–7.1 in) tall with 3-5 stem leaves. The flowers are a translucent white with green stripes and markings, 17–22 mm (0.67–0.87 in) long. Flowering occurs from August to September.[2][3][4]

Taxonomy and naming

Diplodium angulatum was first formally described in 2017 by David L. Jones and Christopher J. French in the Australian Orchid Review, based on a type specimen collected in 1994.[5] The specific epithet was derived from the Latin word angulatus, meaning 'angular', in reference to the angular nature of the flowers.[4] In 2018, Jones and French transferred the species to the genus Pterostylis as P. angulata in a later edition of Australian Orchid Review.[6] Prior to its formal description in 2017, informal names used to refer to this species in various publications included Pterostylis aff. nana,[7][3] Pterostylis sp. 'Helena River',[8][2] and Pterostylis sp. 'limestone'.[9]

Distribution and habitat

Pterostylis angulata is restricted to south-western Western Australia, with a somewhat coastal distribution ranging between Perth in the north and Bunbury in the south, reaching as far east as York and Collie. It is common within this range, which includes a number of reserves and national parks, though populations in some locations have declined due to fires and soil disturbance. It can be found in a variety of habitats including woodlands, swamps, and coastal forests and heaths. It tolerates a range of soil conditions, from sandy soils to heavy clay loams.[4][3]

Conservation status

This snail orchid is listed as "not threatened" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions.[10]

References

1. "Cryptandra angulata". Australian Plant Census. Retrieved 13 February 2023.
2. Brown, Andrew; Dixon, Kingsley; French, Christopher; Brockman, Garry (2013). Field Guide to the Orchids of Western Australia. Simon Nevill Publications. p. 361. ISBN 978-0-9803481-4-9. OCLC 850906217.
3. Hoffman, Noel; Brown, Andrew (2011). Orchids of South-West Australia (3rd ed.). Noel Hoffman. p. 409. ISBN 978-0-646-56232-2. OCLC 747426309.
4. Jones, David L.; French, Christopher J. (2017). "New species in the Diplodium nanum (R.Br.) D.L.Jones & M.A.Clem. complex (Orchidaceae) from Western Australia – 5". Australian Orchid Review. 82 (4): 42–44. ISSN 0045-0782 – via Biodiversity Heritage Library.
5. "Diplodium angulatum". APNI. Retrieved 14 February 2023.
6. Jones, David L.; French, Christopher J. (2018). "New Combinations in the Pterostylidinae". Australian Orchid Review. 83 (4): 55. ISSN 0045-0782 – via Biodiversity Heritage Library.
7. "Pterostylis aff. nana". APNI. Retrieved 14 February 2023.
8. "Pterostylis sp. 'Helena River'". APNI. Retrieved 14 February 2023.
9. "Pterostylis sp. 'limestone'". APNI. Retrieved 14 February 2023.
10. "Pterostylis angulata". FloraBase. Western Australian Government Department of Biodiversity, Conservation and Attractions.