Fitzgerald, R.D. (1882), New Australian Orchids. Gardeners' Chronicle, n.ser 17(433): 495 [tax. nov.]

• Type: Western Australia

George, A.S. (5 May 1971), A check list of the Orchidaceae of Western Australia. Nuytsia 1(2): 189 [secondary reference]

• Lectotype: Western Australia, Fitzgerald. At BM there is a sheet labelled "Prasophyllum triangulare, Albany, Western Australia Oct." in Fitzgerald's hand. This is selected as lectotype.

Hoffman, N. & Brown, A. (1984), Orchids of South-West Australia: 252-253 [secondary reference]

common name: Dark Leek Orchid [n/a]

Green, J.W. (1985), Census of the Vascular Plants of Western Australia Edn. 2: 56 [secondary reference]

Green, J.W. (18 October 1987), Census of the Vascular Plants of Western Australia Edn. 2, Suppl. 5: 6 [secondary reference]

taxonomic synonym: Prasophyllum lanceolatum R.S.Rogers legitimate

Jones, D.L. (1988), Native Orchids of Australia: 266-267 [secondary reference]

common name: Dark Leek Orchid [n/a]

Clements, M.A. in Jones, D.L. (ed.) (August 1989), Catalogue of Australian Orchidaceae. Australian Orchid Research 1: 118 [secondary reference]

Hopper, S.D., van Leeuwen, S.J., Brown, A.P. & Patrick, S.J. (1990), Western Australia's Endangered Flora: 118, 139 [secondary reference]

Hoffman, N. & Brown, A. (1992), Orchids of South-West Australia Edn. 2: 318 [secondary reference]

common name: Dark Leek Orchid [n/a]

Hoffman, N. & Brown, A. (1998), Orchids of South-West Australia Edn. 2 (revised): 318 [secondary reference]

common name: Dark Leek Orchid [n/a]

Paczkowska, G. & Chapman, A.R. (2000), The Western Australian Flora, a descriptive catalogue: 88 [secondary reference]

common name: Dark Leek Orchid [n/a]

Wheeler, J.R., Marchant, N.G. & Lewington, M. (2002), Flora of the South West 1: 381 [secondary reference]

common name: Dark Leek Orchid [n/a]

Brown, A., Dundas, P., Dixon, K. & Hopper, S. (2008), Orchids of Western Australia: 260 [secondary reference]

common name: Dark leek orchid [n/a]

• Etymology: "triangular, alluding to the short narrowly triangular labellum of the species"

Hoffman, N. & Brown, A. (2011), Orchids of South-West Australia Edn. 3: 379 [secondary reference]

common name: Dark Leek Orchid [n/a]

Backhouse, G.N., Bates, R.J., Brown, A.P. & Copeland, L.M. (1 March 2016), Checklist of the orchids of Australia including its island territories: 33, 131 [secondary reference]

Council of Heads of Australasian Herbaria (28 February 2018), Australian Plant Census: - APC [secondary reference]

taxonomic synonym: Prasophyllum lanceolatum R.S.Rogers legitimate taxonomic synonym: Prasophyllum lanceolatum R.S.Rogers isonym

• APC Dist.: WA

Clements, M.A. & Jones, D.L. (2019), Notes on Australasian orchids 5: Paraprasophyllum, a new genus in Prasophyllinae (Diurideae). Australian Orchid Review 84(5): 31 [secondary reference]

Jones, D.L. (January 2021), Native Orchids of Australia Edn. 3: 309 [secondary reference]

common name: Dark Leek Orchid [n/a]

Brown, A. (19 July 2022), The Complete Orchids of Western Australia 2: 94 [secondary reference]

common name: Dark Leek Orchid [n/a]

• Etymology: "From the Latin triangulare (triangular, having three corners), in reference to the narrowly triangular labellum."

---