Concise hierarchy

(Kingdom) Plantae - (Phylum) Tracheophyta - (Class) Spermatopsida

Subsequent positions

Euspermatales (Clade) Crane & Kenrick 1997, nom. cl. inval.

Ref: P.R. Crane & P. Kenrick, 1997: tables 6 (p. 97), 7 (p. 98). [implicit]

Current position

Cycadidae (Subclass) Pax (1894)

Ref: D.J. Mabberley, 2017: App. (p. 999).

Alternative positions

Cycadinae (Class)	Ref: L.J. Audus & V. Heywood, 1981: 10.
Cycadopsida (Class) Brongn. (1843)	Ref: D.J. Mabberley, 2008: 929.
Euspermatales (Clade) Crane & Kenrick 1997, nom. cl. inval.	Ref: P.R. Crane & P. Kenrick, 1997: table 7 (p. 98). [inferred rank]
Gymnospermae ([unranked]) Lindl.	Ref: B. Odé et al., 2010: 70.

Historical positions

Cycadidae (Subclass) Pax (1894)	Ref: D.J. Mabberley, 2017: App. (p. 999).
Cycadidae (Subclass) Pax (1894)	Ref: M.A. Ruggiero et al., 2015b: table 2 (p. 34).
Cycadidae (Subclass) Pax (1894)	Ref: A. Novikoff & B. Barabasz-Krasny, 2015: 58.
Cycadidae (Subclass) Pax (1894)	Ref: M.J.M. Christenhusz et al., 2011: 57.
Gymnospermae ([unranked]) Lindl.	Ref: B. Odé et al., 2010: 70.
Cycadophyta (Phylum) Bessey (1907)	Ref: T.N. Taylor et al., 2009: App. 1 (p. 1028).
Cycadopsida (Class) Brongn. (1843)	Ref: D.J. Mabberley, 2008: 242, 929.
Cycadidae (Subclass) Pax (1894)	Ref: A.B. Doweld, 2001: XV.
Euspermatales (Clade) Crane & Kenrick 1997, nom. cl. inval.	Ref: P.R. Crane & P. Kenrick, 1997: table 7 (p. 98).
Cycadopsida (Class) Brongn. (1843)	Ref: C.J. Cleal & B.A. Thomas, 1995: 14.
Cycadinae (Class)	Ref: L.J. Audus & V. Heywood, 1981: 10.

Number of Subtaxa

2024	Available in Systema Naturae 2000	1f;1g;5s; †1f;4g
1989-present	Systema Naturae 2000: 19 Apr 2023	[1f;1g; †1f;4g]
2017	D.J. Mabberley: App. (p. 999)	[2f]
2015	A. Novikoff & B. Barabasz-Krasny: 58	[1f;1g; †1f;5g]
2011	M.J.M. Christenhusz et al.: 57	[2f;10g]
2011	M.J.M. Christenhusz et al.: 57	[2f;10g]
2008	D.J. Mabberley	[2f;11g]
2001	A.B. Doweld: XV	[1f; †1f]
1995	C.J. Cleal & B.A. Thomas: 14	[1f]