Copy from Discocactus by A.F.H. Buining 1980, page 35 - 39

2. DISCOCACTUS BOOMIANUS Buin. et Bred.

Original description: Succulenta 50, p. 26-29, February 1971.

Plants flat globulair, diameter up to 10 cm, height without cephalium up to 6 cm, green to darkgreen, producing sprouts at the base, branched roots; cephalium diam. up to 4.5 cm., equally high with white wool, up to 3.5 cm. long, bearing greyish bristles with long brownish points, the bristles stand up stiffly and vertically round the cephalium as if they were enclosing the cephalium.

Ribs 16-20, helical, divided completely into mamillalike tubercles, with a diameter at the base of 1 cm and 12-15 mm apart.

Areoles on top of the tubercles, eggshaped, 3 mm long, 1.5 mm wide, at first bearing some white-creamcoloured wool, but soon becoming naked.

Spines 12 (-13), at first yellow to light brown with dark points, soon greyish white with dark points, rough, covered with a greyish white crust; 5 radial spines, at each side of the areole in a form of a comb depressed to the plant, the bottom pair slanting somewhat downwards, the highest pair rising upwards, in addition 1 spine is directed upwards and 1 spine is directed downwards; all spines are up to 3 cm long; if 1 central spine is present it arises at the top of the areole and stands straight up, and is somewhat stronger and up to 3.5 cm long.

Flowerbud greenish; flower slender, funnelshaped, naked, white; pericarp round, diameter 2.5 mm, naked, white, transforming practically without any strictures into the receptale, which is white, with a diameter of less than 4 mm at the base and 5-6 mm higher up; the first scale appears at a distance of 25 mm, its form is lanceolate to lieate, the colour white with a green tip, 1 mm wide; higher up the scales become longer, especially the green tips, and they are 0.5-2.5 cm long and 2-4 mm wide, tapering to a long sharp point; the perianth segments are lanceolate, tapering into sharp points, 2-2.2 cm long, up to 6 mm wide, purely white; the stamens are inserted in the receptacle about 2 cm above the pericarp, until they reach the limb at a distance of 20 mm and fill teh space with yellow anthers, which are 1 mm long, higher up they become a little shorter, and bend towards the style and transform into fine threads, on which the anthers freely dangle hanging down, the stamens and the anthers are together 1-2 mm long; the style is 23 mm long, transparant white, the white stigma lobes reach to about halfway the distance between the highest and lowest anthers, Fruit oblong, a pink to red berry, 18-25 mm long, diameter at the thickest part 8-9 mm, cupula diameter about 5 mm, with persistant perianth.

Seed globose, diameter ca. 1.4 mm, shining black, testa with mamillalike tubercles , along the outside of the cratershaped flat hilum, hilum tissue spongy, ochrecoloured; micrpyle wartlike, clearly visible; funiculus shows a large surface because the funiculus has broken off, arillus sometimes present in small amounts on the testa; embryo somewhat long-eggshaped, without perisperm, cotyledons not visible.

Habitat: on the southern part og the Serra do Espinhaco, middle-Bahia, Brazil, west od Morro do Chapeu, at an altitude of about 900 m, between clefts and on flat rocks, in some places between white pieces of rock, together with Melocactus erythacanthus Buin. et Bred., Melocactus albicephalus Buin. et Bred., Micranthocereus densiflorus Buin. et Bred., and a species of Pseudopilocereus.

p. 37

p. 35