Origin and Habitat: Rebutia minusculaSN|15391]]SN|15391]] has a wide range on northern Argentina (Catamarca, Jujuy, Salta and Tucumán). The species has a patchy distribution but is locally abundant.
Altitude: 1000 to 2800 metres above sea level.
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 K.Schum.
• Echinopsis minuscula (K.Schum.) F.A.C.Weber in Bois
• Eurebutia minuscula (K.Schum.) G.Vande Weghe
• Lobivia minuscula (K.Schum.) H.P.Kelsey & Dayton

• Rebutia minuscula K.Schum.
• Echinopsis minuscula (K.Schum.) F.A.C.Weber in Bois
• Eurebutia minuscula (K.Schum.) G.Vande Weghe
• Lobivia minuscula (K.Schum.) H.P.Kelsey & Dayton
• Rebutia chrysacantha Backeb.
• Lobivia chrysacantha (Backeb.) H.P.Kelsey & Dayton
• Rebutia chrysacantha var. chrysacantha Šída
• Rebutia senilis subs. chrysacantha (Backeb.) Donald
• Rebutia senilis var. chrysacantha (Backeb.) Donald
• Rebutia senilis f. chrysacantha (Backeb.) Buining & Donald
• Rebutia chrysacantha var. elegans (Backeb.) Backeb.
• Rebutia senilis subs. chrysacantha f. elegans (Backeb.) Buining & Donald
• Rebutia senilis var. elegans (Backeb.) Backeb. ex Krainz
• Rebutia senilis f. elegans (Backeb.) Buining & Don
• Rebutia xanthocarpa var. elegans Backeb.
• Rebutia chrysacantha var. kesselringiana (Bewer.) Donald ex Šída
• Rebutia senilis subs. chrysacantha f. kesselringiana (Bewer.) Donald
• Rebutia senilis var. iseliniana f. kesselringiana (Bewer.) Buining & Donald
• Rebutia senilis var. kesselringiana Bewer.
• Rebutia senilis f. kesselringiana (Bewer.) Buining & Donald
• Rebutia chrysacantha var. schieliana (Bewer.) Šída
• Rebutia senilis subs. chrysacantha f. schieliana (Bewer.) Donald
• Rebutia senilis var. schieliana Bewer.
• Rebutia senilis f. schieliana (Bewer.) Donald
• Rebutia minuscula subs. edeltraudianae n.n.
• Rebutia edeltraudae n.n.
• Rebutia minuscula f. kariusiana (Wessner) Donald
• Rebutia calliantha var. kariusiana (Wessner) Buining & Donald
• Rebutia kariusiana Wessner
• Rebutia minuscula subs. violaciflora f. kariusiana (Wessner) Donald
• Rebutia senilis Backeb.
• Lobivia senilis (Backeb.) H.P.Kelsey & Dayton
• Rebutia minuscula var. senilis (Backeb.) Simon
• Rebutia senilis subs. senilis Donald
• Rebutia senilis var. senilis Šída
• Rebutia senilis var. aurescens Backeb.
• Rebutia chrysacantha var. aurescens (Backeb.) Šída
• Rebutia senilis var. iseliniana Krainz
• Rebutia chrysacantha var. iseliniana (Krainz) Donald ex Šída
• Rebutia senilis subs. chrysacantha f. iseliniana (Krainz) Donald
• Rebutia senilis f. iseliniana (Krainz) Buining & Donald
• Rebutia senilis var. lilacino-rosea Backeb.
• Rebutia senilis var. lilacinorosea Backeb.
• Rebutia senilis f. lilacino-rosea (Backeb.) Buining & Donald
• Rebutia senilis subs. senilis f. lilacino-rosea (Backeb.) Donald
• Rebutia senilis var. semperflorens Poind.
• Rebutia senilis var. stuemeri Backeb.
• Rebutia senilis f. stuemeri (Backeb.) Buining & Donald
• Rebutia senilis var. stuemeriana Backeb.
• Rebutia stuemeriana Backeb.
• Rebutia violaciflora Backeb.
• Lobivia violaciflora (Backeb.) H.P.Kelsey & Dayton
• Rebutia minuscula var. minuscula f. violaciflora (Backeb.) Buining & Donald
• Rebutia minuscula subs. violaciflora (Backeb.) Donald
• Rebutia minuscula f. violaciflora (Backeb.) Buining & Donald
• Rebutia violaciflora var. violaciflora Šída
• Rebutia violaciflora var. albispina hort.
• Rebutia violaciflora var. carminea (Buining) Donald
• Rebutia carminea Buining
• Rebutia violaciflora var. knuthiana (Backeb.) Donald
• Lobivia knuthiana (Backeb.) H.P.Kelsey & Dayton
• Rebutia knuthiana Backeb.
• Rebutia minuscula f. knuthiana (Backeb.) Buining & Donald
• Rebutia minuscula subs. violaciflora f. knuthiana Buining & Donald
• Rebutia senilis var. knuthiana R.Hillmann

Description: Rebutia minusculaSN|15391]]SN|15391]] 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.
Habit: 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.
Roots: Fibrous.
Stems: Flattened globose to globose, apex depressed, bright to dull green, 4-6 cm in diameter.
Ribs: 16-21 with low, vertical or slightly spiralled with distinct tubercles.
Tubercles: Low, flat conical.
Areoles: 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.
Spines: 25-30, btistly, whitish to yellowish, fine, 1-5 mm long.
Flowers: 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.
Fruits: Globose, red, to 3-4 mm in diameter, scarlet red when ripe, drying and cracking irregularly.
Seeds: Oblong, about 1 mm long and 0,7 mm wide, hilum basal, somewhat oblique, white, testa glossy black.
Remarks: Rebutia minusculaSN|15391]]SN|15391]] 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.

Bibliography: Major references and further lectures
1) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
2) 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
3) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
4) N. L. Britton, J. N. Rose “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume 4, The Carnegie Institution of Washington, Washington 1923
5) Curt Backeberg “Die Cactaceae: Handbuch der Kakteenkunde” Gustav Fischer Verlag, Stuttgart New York 1982–1985
6) Willy Cullmann, Erich Götz, Gerhard Gröner “Kakteen” edn 5 - Stuttgart Eugen Ulmer, 1984
7) Backeberg, Curt; "Das Kakteenlexikon" p. 384, 1966
8) Donald, John Donald; "The Classification of the Rebutias" Ashingtonia, 2: 43, 1975
9) Hlinecký, Antonín; "Rod Rebutia K. Schumann"; Fričiana, 5/36: 9, 1965
10) Krainz, Hans; "Rebutia minuscula K. Schumann; Die Kakteen", CVc, 15.7.1960
11) Pilbeam, John; "Rebutia", Cactus File Handbook No. 2. Cirio Publishing, Southampton, 1997
12) Pilbeam, John. "Sulcorebutia and Weingartia: a Collector’s Guide." Timber Press, Portland. 1985
13) Pilbeam, John, and David Hunt. "A Sulco Gallery." David Hunt Publishing, Milborne Port, England. 2004
14)Schumann, Karl Moritz; "Gesamtbeschreibung der Kakteen", p. 395, 1898
15) Šída, Otakar; "Atlas kaktusů", tab. 50, 1991
16) Šída, Otakar; "Rod Rebutia", p. 31, 1997
17) Demaio, P., Lowry, M., Ortega-Baes, P., Perea, M. & Trevisson, M. 2013. Rebutia minuscula. In: IUCN 2013. "IUCN Red List of Threatened Species." Version 2013.2. <www.iucnredlist.org>. Downloaded on 06 January 2014.
18) Dan Mahr "Cactus Gems from the High Andes" A Horticulture Information article from the Wisconsin Master Gardener website, posted 3 April 2009 <http://wimastergardener.org/sites/wimastergardener.org/files/rebutias.pdf> Downloaded on 06 January 2014.

Cultivation and Propagation: Rebutia minusculaSN|15391]]SN|15391]] comes from mountainous areas, so like bright light, and cool and dry conditions in the winter. The whole Rebutia minusculaSN|15391]]SN|15391]] complex has delightful flowers and the plants remain compact, and clumps can easily be managed by division. It is easy to cultivate and recommended for beginners.
Growth rate: It is a slow growing but easily flowering species that will make clumps given the best conditions.
Soils: This species is easy to cultivate in a very open mineral mix with at least 50% sand or pumice grit and a pH slightly on the acidic side.
Repotting: They are small container size plants and prefer deep pots and good drainage to accommodate their tap roots, but they rot prone, because of the sensitivity to excess of watering, not easy to get to any large size on their own roots (it's really a challenge to grow them into a large clump). They will occupy a small pot comfortably, and eventually remain a manageable sized house plant. It is better that they are repotted regularly. Repotting will increase the number and size of stems, and will increase the number of flowers produced. Repot yearly until they reach about 100 mm in size, then every two or three years will suffice. Repotting is best done at the end of winter, but can be done at other times, too. Do not water for a couple of weeks after repotting, to reduce risk of root rot via broken roots. A layer of 'pea' gravel at the bottom of the pot improves drainage. A layer of decorative gravel as a top dressing helps prevent the caking of the potting mix, which decreases the rate of water absorption. It also keeps the perlite and pumice from blowing everywhere, and looks nice.
Watering: It requires full sun or light shade and careful watering to keep plant compact, and maintain strong and dense spines and allow the pot to dry out between waterings. Keep dry in winter at a minimum temperature of 0°C. It tends to rot if too wet. The plants can be placed outdoors in April, but protected from rain and direct sunlight. Water them thoroughly when placed out, and again in two weeks, and again in one week. After one month the plants are ready to be placed out in full sun and full rain for the summer. During dry spells the collection is watered once a week, during hot dry spells, twice a week.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: It is reputedly resistant to frost if kept on the dry side prior to, and during, cold weather and requires a winter rest period (hardy to -7° C, or less for short periods). Rebutias grow in nature at high altitudes, and do not thrive well at high temperatures in cultivation. They will often go dormant in mid-summer, and resume growth again when the weather cools in late August. They can tolerate amazingly low temperatures for long periods of time. All species can take a frost, even when not bone dry. It is generally accepted that plants kept at too high a temperature, or watered too much during the winter rest period, will not bloom the following year. They will be perfectly happy in pots outdoors from April to September if protected from torrential rain and hail.
Exposition: The plant tolerates extremely bright situations but enjoys filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Tends to bronze in strong light, which encourages flowering and heavy spine production, but is likely to suffer from sun scorch or stunted growth if over exposed to direct sunlight during the hottest part of the day in summer.
Uses: It is a fine plant for a rock garden or container, contrasts well with agaves, yuccas, and low-growing flowering plants. This variety is also likely to flower as a house plant, but results will depend on a variety of growing conditions.
Pests & diseases: All, especially the young, are susceptible to red spider mites.
Rot: It is especially prone to root rot, therefore, underpot in a smaller container filled with very porous compost. However rot it is only a minor problem with rebutias if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much.
Propagation: Offsets, seeds. Seeds germinate in 7-14 days at 21-27° C in spring or summer remove gradually the glass cover as soon the plants will be well rooted (ca 1-2 weeks) and keep ventilated, no full sun for young plants! The seedlings should not be disturbed until they are well rooted, after which they can be planted separately in small pots. To make a cutting twist off a branch and permit it to dry out a couple of weeks, lay it on the soil and insert the stem end partially into the soil. Try to keep the cutting somewhat upright so that the roots are able to grow downward.
Note: It would appear that in cultivation they grow larger and cluster more vigorously than in habitat.