Origin and Habitat: West of Morro do Chapéu, Bahia, Southern Brazil. Discocactus zehntneriSN|12925]]SN|12925]] v. horstiorum represent the northern populations of Discocactus zehntneriSN|12925]]SN|12925]] subs. boomianus, but this two form cannot be satisfactorily separated and probably are the same.
Altitude range: Around 700–1000 metres above sea level.
Habitat and ecology: This species grows on exposed arenitic rocks or ‘pedra canga’ (iron- and manganese rich conglomerate rock), often with an accumulation of gravel, or in pure quartz sand.

• Discocactus zehntneri subs. horstiorum (P.J.Braun) P.J.Braun & Esteves
• Discocactus zehntneri var. horstiorum P.J.Braun

• Discocactus zehntneri Britton & Rose
• Echinocactus zehntneri (Britton & Rose) Luetzelb.
• Discocactus zehntneri subs. albispinus (Buining & Bredero) P.J.Braun & Esteves
• Discocactus albispinus Buining & Bredero
• Discocactus zehntneri var. albispinus (Buining & Bredero) P.J.Braun
• Discocactus zehntneri f. albispinus (Buining & Bredero) Říha
• Discocactus zehntneri subs. araneispinus (Buining & Bredero) P.J.Braun & Esteves
• Discocactus araneispinus Buining & Bredero
• Discocactus zehntneri var. araneispinus (Buining & Bredero ex J.Theun.) P.J.Braun
• Discocactus zehntneri subs. buenekeri (W.R.Abraham) P.J.Braun & Esteves
• Discocactus buenekeri W.R.Abraham
• Discocactus zehntneri subs. horstiorum (P.J.Braun) P.J.Braun & Esteves
• Discocactus zehntneri var. horstiorum P.J.Braun

• Discocactus zehntneri subs. boomianus (Buining & Bredero) N.P.Taylor & Zappi
• Discocactus boomianus Buining & Bredero
• Discocactus zehntneri var. boomianus (Buining & Bredero) P.J.Braun

Description: Discocactus zehntneri v. horstiorum is a squat tiny little cactus with dark tipped yellowish spines, the flowers are up to 9 cm long. It has tuberous roots. Although having been described as a distinct taxon, it cannot be satisfactorily separated from Discocactus zehntneriSN|12925]]SN|12925]] subs. boomianus based on morphology. In culture it produces just like boomianus many offsets.
Stem: Strongly caespitose, dull-green 4.2 –9.7 in diameter and 1.5 – 6.4 cm tall (often larger in cultivation especially if grafted).
Ribs: 13 – 26 (mostly 16), somewhat spiraled, forming nipple-like tubercles, height of rib at the areole 3 -13 mm, between areoles absent or rarely to 7 mm tall, width of rib at the areole 7-16 mm, between areoles 3-12 nn.
Areoles: Oval, sunken, 2-7 (mostly 5) per ribs.
Radial spines: Interlacing, densely covering the plant, 11 to 21 (mostly 14). 1.3-4.4 (mostly 2.5 cm) cm long, 0.4 mm in diameter, pectinate, flexible spines creamy white or whitish-yellow with dark tips, becoming pale-brown to whitish, recurved backwards, sitting on the plant like spiders.
Central spines: None or rarely 1 to 3.6 cm in length and 0.8 mm in diameter. Cephalium: 6 to 50 mm tall, 13 to 5.4 cm in diameter, at the apex of the plant, creamy-withe to light-brown with yellow to brownish bristles. Bristles on the periphery of the cephalium 1.4 -9.0 in length.
Flowers: White, scented, slender funnelform, up to 9 cm long. The position of the stigma is at the top of the stamens. Each flowering lasts only one night, but that night it produces many flowers.
Fruits: Club-shaped red 2,5 cm long. The plant produces seed-pods twice a year, when it flowers.
Remarks: This plant is part of the Discocactus zehentneri complex which comprises several variable subordinates taxa, but not all are universally recognized.

Bibliography: Major references and further lectures
6) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
7) James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011
8) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
9) MARLON CÂMARA MACHADO “O gênero Discocactus Pfeiff. (Cactaceae) no estado da Bahia, Brasil: variabilidade morfológica, variabilidade genética, taxonomia e conservação” Dissertação apresentada ao Programa de Pós-Graduação em Botânica da Universidade Estadual de Feira de Santana como parte dos requisitos para a obtenção do título de Mestre em Botânica. Universidade Estatual de Feira de Santana – Bahia 2004 pages 91-92
10) BRAUN, P.J. 1990. “D. zehntneri var. horstiorum P.J.Braun.” Kakteen und andere Sukkulenten 69: 218.

Cultivation and Propagation: It is one of the easiest species of the genus to grow, but even so it isn't a plants for beginners, in fact collectors consider the Discocactus to be rarities with requires skilful cultivation. It is rather difficult to grow and frost tender, it can’t stand cold, or even fairly cool temperatures and should be kept at above 15° C if grown on its own roots (8°C if grafted). Need full sun or afternoon shade. They are slow growing and very rot prone when kept on their own roots and though they can’t endure long stretches of total dryness, too much water will rot them, as their weak root systems tend to be inefficient at sucking up water from wet soil. They generally resent being repotted and can take a long time to establish. When grown to maturity, however, it possess an exotic look shared by no other cacti, and it generally attract a lot of attention.
Propagation: Seed or cuttings. Young seedlings are generally grafted on a low stock to keep the plant in a good shape.