Rebutia minuscula has a wide range on northern Argentina (Catamarca, Jujuy, Salta and Tucumán). The species has a patchy distribution but is locally abundant.
Habitat and Ecology:
The species grows in yunga forest on rocky outcrops. It is a rugged area with the high peaks separated by deep valleys; this has resulted in numerous localized forms of these plants, a factor that has resulted in their classification and nomenclature (scientific names) being in a bit of a chaotic state. The major threats are illegal collection and land use change due to agriculture and farming.
Rebutia minuscula is a small clumping cactus species, widespread and extremely variable that has received numerous unnecessary names. Some of its variable forms don't look like the same species.
It is a small solitary or mound-forming cactus. It grows quite close to the ground and offsets only with age. It would appear that in cultivation they grow larger and cluster more vigorously than in habitat. It is a prolific bloomer.
Flattened globose to globose, apex depressed, bright to dull green, 4-6 cm in diameter.
16-21 with low, vertical or slightly spiralled with distinct tubercles.
Very small on top of tubercles, circular to slightly elliptical, brownish, 1,5 mm long, 4 mm apart. Slightly covered with short whitish felt, soon bare.
Slender funnel-form, bright red to violet (but also yellow, orange or even white), to 4 cm long about 3,5 cm wide. Self fertile. Flowers grow in profusion from the older areoles on the bottom half of the stem, often at the stem bases. Pericarpell, almost spherical, pale red, naked, covered with several darker red scales. Floral tube funnel-form, hollow, slightly bent upward, yellowish to reddish, above 15 mm wide, outside covered with scales without hair bristles, which gradually change in the outer tepals. Outer perianth segments (tepals) lanceolate, rounded or slightly apiculate, bright red with a purplish shine. Inner perianth segment slightly wider, usually bright red, gradually changing into yellow down into the throat (but variasble in colour). Filaments pale yellow, anthers yellowish. Style free to base, yellowish, stigma with 4-5 yellowish lobes only slightly protruding the anthers.
Globose, red, to 3-4 mm in diameter, scarlet red when ripe, drying and cracking irregularly.
Oblong, about 1 mm long and 0,7 mm wide, hilum basal, somewhat oblique, white, testa glossy black.
Rebutia minuscula is quite variable. The differences concern the spination and flowers colour, however the size and number of spines is greatly influenced by the conditions of culture, at lower light levels the spines are less numerous, delicate and white, while with strong solar radiation the spines are stronger with a yellowish tint. In some cases differences are referable to separate population, but often occurred over a long period of cultivation due to autogamy. Many such variants have been described as species in the past.