Acanthocalycium thionanthum

Acanthocalycium thionanthum
Kingdom	Plantae
Family	Cactaceae
Subfamily	Cactoideae
Tribe	Trichocereeae
SubTribe
Genus	Acanthocalycium
Species	Acanthocalycium thionanthum
Notes	Taxonomy follows Joël Lodé (2015–2019).

Description

Acanthocalycium thionanthum is a small to medium-sized cactus species native to Argentina. Plants are usually solitary, globose to short cylindrical, dark green to gray-green, reaching up to 12 cm in height and 10 cm in diameter.

The ribs are 9–15, rounded and slightly notched. Areoles are elliptical. Spines are awl-shaped, gray with darker tips, typically 1–1.5 cm long. Central spines (1–4) may be absent, while radial spines number 5–10.

Flowers are somewhat bell-shaped and variable in color, ranging from bright yellow to red or white, up to 4.5 cm in length and diameter. Floral tubes bear dark, spine-tipped scales along with hairs and bristles. Fruits are globose, dry, and dehiscent, up to 1 cm in diameter.

Distribution

• Argentina – Salta Province

Taxonomy

According to Joël Lodé, this species is placed in the genus Acanthocalycium.

Synonyms

The following names have been applied to this species:

• Echinopsis thionantha
• Echinocactus thionanthus
• Lobivia thionantha
• Echinocactus chionanthus
• Lobivia chionantha
• Echinopsis chionantha
• Acanthocalycium chionanthum
• Acanthocalycium brevispinum
• Echinopsis brevispinum
• Acanthocalycium griseum
• Acanthocalycium catamarcense

Notes

• Species shows high variability in flower color and spine development.
• Frequently encountered under different generic names in horticulture.
• One of the more widely distributed species within the genus.

Cultivation

This species is relatively easy to cultivate:

• prefers well-draining mineral substrate
• requires bright light for compact growth
• tolerates cool temperatures if kept dry in winter