Acanthocalycium spiniflorum aka Golden Barrel Cactus

Acanthocalycium spiniflorum is a cactus native to northern Argentina. It belongs to the cactus family, Cactaceae. Garden sources also call it Echinopsis spiniflora. Its range includes Catamarca, Córdoba, La Rioja, San Luis and Santiago del Estero. It grows on mountain soils in monte shrubland and chaco. These sites have cold spells in winter. The species has a broad range and grows abundantly in places.

Plants often have one stem, though basal shoots can form. The round stem becomes more upright with age. Its skin ranges from pale to dark green. The RHS gives a garden height of 1.6–3.3 feet [0.5–1 m]. Its spread reaches 0.3–1.6 feet [0.1–0.5 m]. LLIFLE describes much smaller wild plants, around 0.4–0.5 feet [0.12–0.15 m] tall. In warm cultivation, it records stems approaching 2 feet [0.6 m]. The RHS allows five to ten years for plants to mature.

The stem has about 16–20 sharp ribs with small bumps. Areoles sit on these bumps and bear yellow-brown felt when young. They lose much of this covering with age. Each areole carries roughly 10–20 thin, straight spines. Their length, shade and number vary between plants. Young spines can look brown or yellow, often with dark tips. Older spines turn grey or pale yellow. Flowers appear near the stem tip in summer. They open into bell, funnel or trumpet shapes. Their petals range from white to pink and pale purple. Pointed scales cover the green flower tube, and hairs cover the buds. The round fruit keeps its scales and splits lengthwise when ripe. Its seeds are egg-shaped and brown to black.

Grow this cactus in full sun in a sheltered spot. The RHS recommends growing it under glass in Britain. Use peat-free, loam-based compost with extra grit for drainage. Loam and sandy soils suit it across a broad pH range. Water moderately during growth, then reduce watering during dormancy. Give balanced liquid feed two or three times during growth. Its H2 rating means it tolerates cool conditions but not freezing.

The RHS lists it for pots and patio displays. Its ribbed stems, spines and summer flowers provide the main interest. It tolerates drought and needs no pruning. Raise new plants from seed or offsets. Mealybugs can attack it, though the RHS reports few disease problems. The supplied sources do not establish its edibility or toxicity.