Uebelmannia pectinifera

Uebelmannia pectinifera is a solitary cactus 50 (-80)cm tall. It is dark reddish-green to reddish-brown, with off-white scales. (In cultivation the color of the plants depends on sun exposure, the plants grown in shadow are green with white stripes, while the ones in full sun take on a dark frost brown or purple color)
Flowers: Diurnal, funnel-shaped greenish yellow. They are 15 mm long, 12 mm in diameter.
Blooming season: Flowers come sporadically from early Spring to late Summer
Cultivation and propagation: This tropical cactus loves warm moist, humid conditions and mist spraying is a must in summer.

Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz