Subspecies, varieties, forms and cultivars of plants belonging to the Ferocactus hamatacanthus group

• Ferocactus hamatacanthus (Muehlenpf.) Britton & Rose: has stems up to 60 cm tall, ribs rounded but not compressed and brownish-reddish spines. Distribution: Southern Texas, New Mexico, and northern Mexico.
• Ferocactus hamatacanthus var. crassispinus (Engelm.) L.D.Benson
• Ferocactus hamatacanthus f. cristata hort.: is a crested cactus that forms fan-shaped stems with especially hooked spines. There are several quite different clones.
• Ferocactus hamatacanthus var. davisii (Houghton): This form differs for having very clear (almost white) and very shining flowers. Distribution: Tamaulipas, Mexico.
• Ferocactus hamatacanthus var. flavispinus (Meinsh.): has long golden yellow spines. In some plants, particularly on the upper one-half or one-third of the stems, the collective dominant colour of the spines is yellow. (Same as Hamatocactus sinuatus ?)
• Ferocactus hamatacanthus var. longihamatus (Galeotti ex Pfeiff.): has great rounded ribs composed of massive tubercles swelling around each areole and very long central spines, curved or slighly hooked. Distribution: Durango.
• Ferocactus hamatacanthus var. papyracanthus (Kunth): has central spines apically hooked or almost twist into ringlets, principal central spine flattened more or less papery. Distribution: Tamaulipas.
• Ferocactus hamatacanthus subs. sinuatus (A.Dietr.) N.P.Taylor: Recognizable for its smaller stem up to 30 cm tall and 20 cm in diamter. Ribs are about 13, narrow and more acute at the crest than in var. hamatacanthus. Distribution: plain of the Rio Grande in southeastern Texas and neighboring Mexico.
• Ferocactus hamatacanthus subs. sinuatus f. cristatus hort.: Crested form, recognizable for the yellow spines. Known in cultivation only.