Origin and Habitat: South Bolivia (Chuquisaca, Tarija, Potosí ), North Argentina (Jujuy, Salta )
Altitude: 2900-4300 metres above sea level.
Habitat: It grows in very arid mountainous area where its thick hair protects it against light night frosts and from the intense sunlight found at the altitude in which it resides.
Habit: It branches at the base and forms clumps of short chunky columnar shoots that can lay sideways with time. In young plants the shoots are like thick spheres and difficult to recognise as belonging to an Oreocereus.
Stems: 6-10 cm in diameter, at first almost globular, then up to1 m tall (usually less than 50 cm), light-green with a dense, cocoon-like covering of wool (actually radial spines that have evolved to resemble “hairs”), which entirely covers the stem and from which spines emerge.
Ribs: 15-25, low, strongly tuberculate.
Radial spines: Oreocereus trollii has 10 to 15 very fine creamy-white or greyish modified spines up to 7 cm long that look like hair or wool.
Central spines: 3-5, stout awllike-like up to 5 cm yellow, orange, orange-red or brown, dark tipped, protruding through the fine, woolly, hair-like radial spines..
Flowers: Up to 4 cm long pink to violet red and semi-tubular in shape.
Blooming season: Summer.