About Trichocereus macrogonus (Salm-Dyck) Riccob.
Trichocereus macrogonus (Salm-Dyck) Riccob. has erect stems that grow 2.5–5 m (8–16 ft) tall. Its branches generally have a diameter of 6–15 cm (2–6 in), and may occasionally grow larger. There are typically seven or eight ribs at the base of the stem; overall, the species usually has relatively few ribs, most commonly six to eight, and occasionally five or nine. The circular areoles are 6 mm (0.2 in) across, grey or dark brown, bear needle-like spines, and are spaced more than 2.5 cm (1.0 in) apart. The number and length of the spines varies: older areoles may have up to 20 spines total, with three or four prominent, longer, more robust central spines that reach up to 5 cm (2.0 in) long. Spines are darker at their tips. Flowers are mostly produced near the top of stems, and can grow up to 21 cm (8.3 in) long. Tepals are typically pale yellow or yellowish green, and rarely pink. The small seeds are broadly ovoid, and measure 0.9–1.1 mm (0.04–0.04 in) long. As of November 2025, Plants of the World Online lists this species as native to Bolivia and Peru, and introduced to the Balearic Islands, the Canary Islands, Colombia, and mainland Spain. However, the species is widely cultivated, which makes determining its true original origin difficult. It has been speculated that the original native distribution may only include the high valleys of Peru, and possibly northwestern Bolivia.
