Ferocactus glaucescens (A. P. de Candolle) Britton & Rose 1922
Echinocactus glaucescens A. P. de Candolle 1829
Bisnaga glaucescens (A. P. de Candolle) Orcutt 1926
Echinocactus pfeifferi Zuccarini 1837
Ferocactus pfeifferi (Zuccarini) Backeberg 1961
Ferocactus glaucescens means roughly “fierce bluish cactus”—a pretty good description, since the body is bluish green (“glaucous”) and the spines are not to be trifled with. These cacti are found only in Hidalgo, Mexico.
Identification: Plants are distinctly bluish in color, ball-shaped, usually with flattened tops, found singly or in multiply branched groups. They are up to 18" (45 cm) high and 20" (50 cm) around, with 12-17 ribs. (The Arizona-Sonara Desert Museum lists sizes up to 12' (3.7 m), but I couldn’t confirm that elsewhere and it may be a misprint.) Spines are in groups of 6-7, to 1¼" (3.5 cm) long. Yellow, bell-shaped flowers are up to 1¾" (4.5 cm) long. Whitish or yellowish fruits are up to ⅞" (2.5 cm) long.
Ferocactus glaucescens on Cactus Art: the World of Cacti & Succulents
Ferocactus glaucescens on Desert-tropicals.com
Ferocactus glaucescens on CactiGuide.com
Ferocactus glaucescens at the Arizona Sonora Desert Museum Sonoran Desert Digital Library
Ferocactus glaucescens at the South Coast Botanic Garden
Ferocactus glaucescens description by Thomas H. Kent, last updated 25 May 2020.
Range: Zones 9b-11: