Endlicher, S.F.L. in Endlicher, S.F.L., Fenzl, E., Bentham, G. & Schott, H.W. (April 1837), Rutaceae. Enumeratio plantarum quas in Novae Hollandiae ora austro-occidentali ad fluvium Cygnorum et in Sinu Regis Georgii collegit Carolus liber baro de Hügel: 15, adnot. [tax. nov.]

• Type: "Sterile country on the Lachlan River (A. Cunningh. 24 Mai 1817. in Oxley's First Expedition.)"

Mueller, F.J.H. von (February 1862), Thalamiflorae. The Plants Indigenous to the Colony of Victoria 1: 123-125, 229 [secondary reference]

taxonomic synonym: Eriostemon brevifolius A.Cunn. ex Endl. legitimate taxonomic synonym: Eriostemon rhombeus Lindl. legitimate taxonomic synonym: Eriostemon halmaturorum F.Muell. legitimate

Bentham, G. (30 May 1863), Flora Australiensis 1: 335 [secondary reference]

taxonomic synonym: Eriostemon rhombeus Lindl. legitimate

Mueller, F.J.H. von (1882), Systematic Census of Australian Plants: 11 [secondary reference]

Mueller, F.J.H. von (December 1889), Second Systematic Census of Australian Plants: 20 [secondary reference]

Tate, R. (1890), A Handbook of the Flora of Extratropical South Australia: 24 [secondary reference]

Dixon, W.A. (1906), The Plants of New South Wales: 50 [secondary reference]

Bailey, F.M. (1913), Comprehensive Catalogue of Queensland Plants: 76 [secondary reference]

Wilson, Paul G. (10 December 1970), A taxonomic revision of the genera Crowea, Eriostemon and Phebalium (Rutaceae). Nuytsia 1(1): 29-30, Fig. 2 (4-6) [secondary reference]

• Type: " "Sterile country on the Lachlan River (A. Cunningham. 24 Mai 1817, in Oxley's First Expedition.)" Holotypus: K (photo seen) Lachlan River, N.S.Wales, A. Cunningham No. 163, May 1817."

taxonomic synonym: Eriostemon rhombeus Lindl. legitimate

• Etymology: "difformis = defformed [deformed], unevenly shaped"

Wilson, Paul G. (10 December 1970), A taxonomic revision of the genera Crowea, Eriostemon and Phebalium (Rutaceae). Nuytsia 1(1): 31 [misapplied]

misapplied to: Eriostemon angustifolius Paul G.Wilson legitimate by Tate, R. (1890), A Handbook of the Flora of Extratropical South Australia: 24

Willis, J.H. (1973), A Handbook to Plants in Victoria Edn. 2, 2: 333 [secondary reference]

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. & Leigh, J.H. (1981), Plants of Western New South Wales: 445 [secondary reference]

Jacobs, S.W.L. & Pickard, J. (1981), Plants of New South Wales: 192 [secondary reference]

Ross, E.M. in Stanley, T.D. & Ross, E.M. (1984), Rutaceae. Flora of South-eastern Queensland 1: 465 [secondary reference]

taxonomic synonym: Eriostemon rhombeus Lindl. legitimate

Weston, P.H. & Porteners, M.F. in Harden, G.J. (ed.) (1991), Eriostemon. Flora of New South Wales 2: 251 [secondary reference]

Wilson, Paul G. (16 September 1998), A taxonomic review of the genera Eriostemon and Philotheca (Rutaceae: Boronieae). Nuytsia 12(2): 249 [basionym]

basionym of: Philotheca difformis (A.Cunn. ex Endl.) Paul G.Wilson legitimate

Bayly, M.J. in Walsh, N.G. & Entwisle, T.J. (ed.) (1999), Eriostemon. Flora of Victoria 4: 181 [pro parte misapplied]

pro parte misapplied to: Eriostemon angustifolius Paul G.Wilson legitimate by Willis, J.H. (1973), A Handbook to Plants in Victoria Edn. 2, 2: 333

Weston, P.H. & Harden G.J. in Harden, G.J. (ed.) (2002), Philotheca. Flora of New South Wales Revised Edition 2: 295 [nomenclatural synonym]

nomenclatural synonym of: Philotheca difformis (A.Cunn. ex Endl.) Paul G.Wilson legitimate

Council of Heads of Australasian Herbaria (2007), Australian Plant Census: - [nomenclatural synonym]

nomenclatural synonym of: Philotheca difformis (A.Cunn. ex Endl.) Paul G.Wilson legitimate

Wilson, Paul G. in Wilson, A.J.G. (ed.) (2013), Philotheca. Flora of Australia 26: 378 [nomenclatural synonym]

nomenclatural synonym of: Philotheca difformis (A.Cunn. ex Endl.) Paul G.Wilson legitimate

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