Origin and Habitat: Salta, Argentina.

• 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 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 senilisSN|15406]]SN|15395]] var. iseliniana ( Occasionally misspelled "iseliana" or even "ischeliana") is a superfluous or questionable name, first published in 1946 by Krainz. This controversial “variety” is somewhat similar and not easy to tell apart from standard Rebutia senilisSN|15406]]SN|15395]] if not for the bright orange or orange-red flowers and thinner spines, sometimes pure white, often with a yellowish cast. The plants clump naturally and are very floriferous and attractive. Yellow flowering specimens are also frequent in cultivation. Regrettably most plants in cultivation under the name Rebutia senilisSN|15395]]SN|15395]] var. iseliniana seldom match up to the original description, being usually raised from commercial seed which have often been wrongly identified.
Taxonomy notes: It is very difficult to distinguish Rebutia chrysacanthaSN|15395]]SN|15406]] from Rebutia senilisSN|15391]]SN|15395]] var. iseliniana if guided by the description given by Backeberg for Rebutia chrysacanthaSN|15395]]SN|15406]] (Kaktus-ABC, p. 276/277), for it could apply equally well to that of the senilis variety, especially when the latter develops yellow spines as it does when grown slowly in full sun. The flowers of the two plants are very similar, and differ only in shade. Probably Rebutia chrysacanthaSN|15395]]SN|15406]] var. kesselringiana could also be included here. On the other hand both Rebutia chrysacanthaSN|15406]]SN|15406]] and Rebutia chrysacanthaSN|15406]]SN|15406]] var. kesselringiana are to be diagnosed as varieties of Rebutia senilisSN|15406]]SN|15395]], suggesting that there is not really a fundamental difference between them. Recently Rebutia senilisSN|15406]]SN|15395]] var. iseliniana has been included within Rebutia minusculaSN|15395]]SN|15391]] (Anderson, 2001).
Stem: Same as Rebutia senilisSN|15406]]SN|15395]]. Small, flattened-globular to spherical.
Spines: Hair-like, very fine, more loosely arranged than those of Rebutia senilisSN|15395]]SN|15395]], pure white, often with a yellowish tone.
Flowers: Usually large, about 40-50 mm long and 40 mm wide, exclusively from the base of the stem c. 3-4 mm above the the surface of the ground (like in Rebutia chrysacanthaSN|15395]]SN|15406]]). Buds red, with pointed scales paler towards the tips. Outer perianth segments light orange to orange-red inner perianth segments 14-17, 20-25 mm long, 7-8 mm wide, lanceolate, usually bright orange-red (occasionally yellow), with or without a darker mid-strip, and often with a brown throat, outside often with purple gloss. Ovary c. 4 mm in diameter, with pale orange to greenish-brown scales. Tube slender yellow-orange. Pistil white to yellow-white. Stigma white, with 5-7 thin stigma lobes, above the anthers. Filaments bright yellow, anthers creamy-yellow. Mostly self-fertile.
Fruits: Spherical, 5-7 mm diameter, yellow-orange, with red-green-scales (like in Rebutia chrysacanthaSN|15395]]SN|15406]]), at times with a few bristles.
Seeds: Rough but shiny black, about 1 mm long.

Bibliography: Major references and further lectures
1) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
2) Cyril Marsden, Herbert Spencer Jackson “Rebutia, Including Aylostera and Sulcorebutia” Macmillan, 1968
3) John Pilbeam “Rebutia” Cirio Pub. Services, 01 May 1997
4) Backeberg, Curt; Knuth, Frederic Marcus “Kaktus-ABC”, p. 277, 1936
5) Backeberg C. “Das Kakteenlexikon” p. 383, 1966
6) O. Šída, Rod Rebutia, p.18, 1997
7) H. Krainz, “Der Schweizer Garten”, p.284, 1946
8) J. Donald, in: Cactus (Paris), 9: 40, 1954
9) A. F. H. Buining, im: J. Donald, Sukkulentenkunde, 7/8: 99, 1963
10) The Cactus and Succulent Journal of Great Britain, Cactus and Succulent Society of Great Britain, 1952

Cultivation and Propagation: Rebutia senilisSN|15391]]SN|15395]] var. iseliniana comes from mountainous areas, so like bright light, and cool and dry conditions in the winter. The whole Rebutia minusculaSN|15395]]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.