Cereus aethiops

Cereus aethiops is a shrubby cactus in the cactus family. Its native range runs from Uruguay into Argentina. It grows in a subtropical climate across several dry habitats. These include dry woods, scrub, and open grasslands. In Argentina, it grows from sea level to 2,625 feet [800 metres]. Plants can grow back from underground parts after stems are cut.

This slow-growing cactus can live for many years. It reaches about 6.6 feet [2 metres] tall. A mature clump can spread 4.9 feet [1.5 metres] wide. Most branches rise from the base of the plant. The stems stand upright, though some lie along the ground. Their dark blue-green skin can take on purple tones. Young stems have a blue coat of wax. Low, rounded ribs run along each stem. Large, near-black areoles bear groups of sharp spines. Each group has one to four stout central spines. Seven to twelve thinner spines spread around them.

The scented flowers open at night. Plants may bloom at just 1.6 feet [0.5 metres] tall. Each flower forms a long funnel with small outer scales. Blooms reach about 0.7 feet [0.22 metres] in length. The inner flower parts are white. Outer parts can show rose or purple shades. The overall bloom may look white or pale pink. The fruit looks like a prune with a thick skin. It turns brown-red to purple as it ripens. Its smooth surface can have a light waxy bloom. The seeds are black.

Growers keep this cactus for its shape and flowers. It makes most of its growth in summer. Use a mineral cactus mix that lets water drain fast. Rich compost can lead to long, stretched stems. Give the roots room and choose a pot with drainage. Repot every other year, or when roots outgrow the pot. Summer feeding can use a fertiliser rich in potassium. Seeds and cuttings both serve for propagation.

Good airflow matters, since poor airflow can lead to rot. Newly planted specimens need care in this respect. Reports suggest brief cold tolerance near 10°F [-12°C] when dry. Yet frost-free care offers the safer choice. Wild populations are sparse but stable across a broad range. Soybean farming threatens some sites in the Chaco.