Concise hierarchy

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

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

†Caytoniopsida (Class) H.H.Thomas ex Frenguelli (1946)

Ref: Новіков, А. & Барабаш-Красни, Б. / Novikoff, A. & Barabasz-Krasny, B., 2015: 58.

Alternative positions

Euspermatales (Clade) Crane & Kenrick 1997, nom. cl. inval.	Ref: P.R. Crane & P. Kenrick, 1997: table 7 (p. 98). [inferred rank]
gymnosperms ([unranked])	Ref: K.M. Pryer et al., 2004: fig. 10.6. [inferred rank]
†Pteridospermae (Class)
†Pteridospermopsida (Class)	[implicit]

Historical positions

†Caytoniopsida (Class) H.H.Thomas ex Frenguelli (1946)	Ref: A. Novikoff & B. Barabasz-Krasny, 2015: 58.
†Pteridospermophyta (Phylum)	Ref: T.N. Taylor et al., 2009: App. 1 (p. 1028).
core seed plants ([unranked])	Ref: J. Cracraft & M.J. Donoghue, 2004: fig. 10.6. [implicit]
gymnosperms ([unranked])	Ref: K.M. Pryer et al., 2004: fig. 10.6.
†Caytoniopsida (Class) H.H.Thomas ex Frenguelli (1946)	Ref: A.B. Doweld, 2001: XXI.
Euspermatales (Clade) Crane & Kenrick 1997, nom. cl. inval.	Ref: P.R. Crane & P. Kenrick, 1997: table 7 (p. 98).
Cycadinae (Class)	Ref: L.J. Audus & V. Heywood, 1981

Number of Subtaxa

2024	Available in Systema Naturae 2000	†1f;5g
1989-present	Systema Naturae 2000: 19 Apr 2023	[; †1f;5g]
2015	A. Novikoff & B. Barabasz-Krasny: 58	[; †1f;5g]
2001	A.B. Doweld: XXI	[; †1f]