Echinopsis pachanoi is native to Ecuador and Peru. Its stems are light to dark green, sometimes glaucous, with a diameter of 6–15 cm (2.4–5.9 in) and usually 6–8 ribs. The whitish areolas may produce up to seven yellow to brown spines, each up to 2 cm (0.8 in) long although typically shorter in cultivated varieties, sometimes being mostly spineless. The areolas are spaced evenly along the ribs, approximately 2 cm (0.8 in) apart. Echinopsis pachanoi is normally 3–6 m (10–20 ft) tall and has multiple branches, usually extending from the base but will emerge around broken branches. The tallest recorded specimen was 12.2 metres (40 ft) tall. White flowers are produced at the end of the stems; they open at night and last for about two days. Large numbers can be produced by well established cacti and may open new flowers over a period of weeks. The flowers are large, around 19–24 cm (7.5–9.4 in) long with a diameter of up to 20 cm (7.9 in) and are highly fragrant. There are black hairs along the length of the thick base leading to the flower. Oblong dark green fruits are produced after fertilization, about 3 cm (1.2 in) across and 5–6 cm (2.0–2.4 in) long.