Acanthocalycium thionanthum subsp. glaucum is a lovely small cactus that resembles a Copiapoa when not in bloom.
Scientific Name
Acanthocalycium thionanthum subsp. glaucum (F.Ritter) Lodé
Synonym(s)
Acanthocalycium glaucum, Echinopsis glaucina, Echinopsis thionantha subsp. glauca, Lobivia thionantha var. glauca
Scientific Classification
Family: Cactaceae
Subfamily: Cactoideae
Tribe: Trichocereeae
Genus: Acanthocalycium
Etymology
The subspecific epithet "glaucum" (pronounced GLAW-kum) means "bright, sparkling, gleaming, grayish" and refers to the powdery bloom on the stem of this species.
Origin
Acanthocalycium thionanthum subsp. glaucum is native to northwestern Argentina. It grows on rocky mountain slopes in the Catamarca province.
Description
Acanthocalycium thionanthum subsp. glaucum, also known as Acanthocalycium glaucum or Echinopsis glaucina, is a small cactus with a spherical to short cylindrical stem that features 8 to 14 ribs lined with clusters of spines. Typically growing solitary, this cactus can reach a height of 6 inches (15 cm) and a diameter of 3.2 inches (8 cm). It is bluish-green with a dusty-looking coating. The felted areoles bear 5 to 10 dark brown to black radial spines, each measuring up to 1 inch (2.5 cm) long. Central spines are usually absent, although there may occasionally be 1 to 2 present.
In late spring and early summer, Acanthocalycium thionanthum subsp. glaucum produces attractive funnel-shaped flowers that can be yellow, red, or red with a yellow or orange center. The flowers can reach a length and diameter of 2.4 inches (6 cm) long. Their floral tube is covered in brownish-white bristles and spine-tipped scales. The fruits are dark green and globose, measuring up to 0.8 inches (2 cm) in diameter.
How to Grow and Care for Acanthocalycium thionanthum subsp. glaucum
Light: Acanthocalycium thionanthum subsp. glaucum thrives when exposed to intense sunlight and can be grown in full sun to partial shade. Placing it near a window that receives about 6 hours of direct sun daily is ideal if grown indoors. It is best to move it outdoors in the spring but gradually expose it to direct sunlight to avoid sunburn.
Soil: For healthy growth, use sandy or gritty soil with good drainage. Overwatering and poor drainage can lead to root rot. A commercial potting mix designed for cacti works well, or you can make your own mix.
Temperature: This cactus can withstand high temperatures, but during the winter, it prefers cooler temperatures. It grows best in USDA Plant Hardiness Zones 9a to 11b, with average minimum winter temperatures ranging from 20 to 50 °F (-6.7 to 10 °C).
Watering: During the growing season, water Acanthocalycium thionanthum subsp. glaucum thoroughly, but allow the soil to dry out completely before watering again. Avoid letting the container sit in a saucer of water. During the winter, suspend watering.
Fertilizing: For optimal growth, feeding this cactus with a water-soluble fertilizer is recommended during the growing season. However, during the winter, when it goes dormant, fertilization is not required.
Repotting: Acanthocalycium thionanthum subsp. glaucum can stay in its pot for years. Repot it only when it has outgrown its current pot or when the soil has degraded. The best time to repot is in late winter or early spring. Ensure that the soil is dry before repotting, and choose a slightly larger pot with drainage holes at the bottom.
Propagation: Since this cactus rarely produces offsets, it is usually propagated from seeds. Sow the seeds in late spring or summer.
Learn more at How to Grow and Care for Echinopsis.
Toxicity of Acanthocalycium thionanthum subsp. glaucum
Acanthocalycium thionanthum subsp. glaucum is non-toxic to humans or pets. However, keep it away from pets and children as it has sharp spines.
Links
- Back to genus Acanthocalycium
- Succupedia: Browse succulents by Scientific Name, Common Name, Genus, Family, USDA Hardiness Zone, Origin, or cacti by Genus
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