2113712 536341 Horkelia pygmaea (A. Gray) Rydb. [80 562612 Ivesia pygmaea A. Gray] P.A. Rydberg, Monogr. N. Amer. Potent.: t. 93, fig. 1-7 (1898)
 
2114332 536309 Horkelia gordonii Hook. P.A. Rydberg, Monogr. N. Amer. Potent.: t. 92, fig. 7-11 (1898)
 
2677136 535458 Hoodia gordonii (Masson) Sweet ex Decne. [125 971910 Stapelia gordonii Masson] F. Masson, Stapel. Nov. (uncoloured edition): t. 39 (1797) [F. Masson]
 
3591906 535458 Hoodia gordonii (Masson) Sweet ex Decne. [125 971910 Stapelia gordonii Masson] F. Masson, Water-colour drawings of Plants from South Africa, Canaries, Azores, West Indies (unpublished): t. 26 () [F. Masson]
 
3593912 535458 Hoodia gordonii (Masson) Sweet ex Decne. [80 971910 Stapelia gordonii Masson] R.J. Gordon, Travels in South Africa (unpublished botanical drawnings): t. 91 (1777) [F. Masson]