Origin and Habitat: Tarija, Bolivia.
Altitude: 2200-3800 metres above sea level.
Habitat: It is found in high, dry, rocky grasslands in rocky slopes of the Andes in fully exposed sites. The dense covering of spines reduces the interception of solar radiation by the stem surface lowering the risks of overheating the apex during a summer day and of freezing during a winter night.

• Rebutia archibuiningiana F.Ritter
• Aylostera archibuiningiana hort.
• Aylostera fiebrigii var. archibuiningiana hort. sensu D.R.Hunt
• Rebutia buiningiana F.Ritter non Rausch
• Rebutia spinosissima var. archibuiningiana hort. sensu Pilbeam, E.F.Anderson

• Rebutia fiebrigii (Gürke) Britton & Rose in L.H.Bailey & L.H.Bailey
• Aylostera fiebrigii (Gürke) Backeb. in Backeb. & F.M.Knuth
• Echinocactus fiebrigii Gürke
• Echinorebutia fiebrigii (Gürke) Frič & Kreuz.
• Rebutia albipilosa F.Ritter
• Aylostera albipilosa (F.Ritter) Backeb.
• Rebutia archibuiningiana F.Ritter
• Aylostera archibuiningiana hort.
• Aylostera fiebrigii var. archibuiningiana hort. sensu D.R.Hunt
• Rebutia buiningiana F.Ritter non Rausch
• Rebutia spinosissima var. archibuiningiana hort. sensu Pilbeam, E.F.Anderson
• Rebutia cajasensis F.Ritter
• Aylostera cajasensis (F.Ritter) Mosti & Papini
• Rebutia cintiensis F.Ritter
• Aylostera cintiensis (F.Ritter) Mosti & Papini
• Rebutia donaldiana A.B.Lau & G.D.Rowley
• Aylostera donaldiana (A.B.Lau & G.D.Rowley) Mosti & Papini
• Rebutia fiebrigii var. azurduyensis (J.de Vries)
• Aylostera azurduyensis J.de Vries
• Aylostera fiebrigii var. azurduyensis (J.de Vries) Mieczak.
• Rebutia azurduyensis (J.de Vries) hort.
• Rebutia fiebrigii var. densiseta (Cullmann) Oeser
• Rebutia fiebrigii f. densiseta Cullmann
• Rebutia fiebrigii var. vulpes F.Ritter
• Rebutia flavistyla F.Ritter
• Aylostera flavistyla (F.Ritter) Mosti & Papini
• Rebutia hoffmannii Diers & Rausch
• Aylostera hoffmannii (Diers & Rausch) Mosti & Papini
• Rebutia ithyacantha (Cárdenas) Diers
• Mediolobivia ithyacantha Cárdenas
• Rebutia jujuyana Rausch
• Aylostera jujuyana (Rausch) Mosti & Papini
• Rebutia kieslingii Rausch
• Aylostera kieslingii (Rausch) Mosti & Papini
• Rebutia lateritia n.n.
• Aylostera lateritia n.n.
• Rebutia muscula F.Ritter & Thiele
• Aylostera muscula (F.Ritter & Thiele) Backeb.
• Rebutia pulchella Rausch
• Aylostera pulchella (Rausch) W.Haage
• Rebutia pulchella var. prolifera Rausch
• Aylostera pulchella var. prolifera hort.
• Rebutia simoniana Rausch
• Aylostera simoniana (Rausch) Mosti & Papini
• Rebutia sp. Huari Huari
• Rebutia spinosissima Backeb.
• Aylostera spinosissima Backeb. in Backeb. & F.M.Knuth
• Rebutia tamboensis F.Ritter
• Aylostera tamboensis (F.Ritter) Mosti & Papini
• Rebutia vallegrandensis Cárdenas
• Aylostera pumila A.B.Lau, n.n.
• Aylostera vallegrandensis (Cárdenas) Mosti & Papini
• Rebutia walteri Diers
• Aylostera walteri (Diers) Mosti & Papini

Description: Rebutia archibuiningianaSN|4932]]SN|5051]] is probably one of the many geographical forms of the extremely variable Rebutia fiebrigiiSN|5051]]SN|4932]] with glassy-white to yellowish, silky, short spines and light green tubercles thickly covering the body. The body is made invisible by the spines. It produces vibrant orange-red flowers. The dense spines would protect it from the extremes of cold and sunshine.
Habit: It is a small solitary or mound-forming cactus spreading out to 15 cm. 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.
Stem: Roundish to slightly elongated, depressed at the top, 50-60 mm wide and tall, dark green, flat, covered by distinctive tubercles similar to a Mammillaria, that are not easy to see through the dense small spines.
Ribs: About 18, straight to spirally arranged tuberculate
Tubercles: About 5 mm high conical.
Areoles: Elliptical, white-tomentose.
Spines: 30-40, all more or less similar, bristly, glassy-white, creamy-yellow or pale brownish, bristle-like, fine and soft.
Radial spines: Less than 10 mm long, white.
Central spines: 2 to 5 somewhat longer, to 20 mm long creamy white.
Flowers: Flowers produced basally or halfway up the stems, curving upward, bright orange or vermilion red, funnel-shaped, 25-45 mm long, 4 cm diameter. Tube narrow 10-18 mm long, outside reddish, inside pale. Ovary spherical, about 4 mm wide, with small triangular scales with few white wool and few white bristly hairs. Tepals vermilion red, rather rounded, often slightly serrated, 14-16 mm long, 4-6 mm wide. Filaments white, anthers golden yellow. Pistil white, with 5-6 white stigma lobes 2-3 mm long, slightly protruding the anthers.
Blooming season: Flowers all tend to come in one late Spring rush, rather than spread over the Summer, and remain open for up to six days.
Fruit: Tiny, spherical, berrylike, about 5 mm wide, greenish or reddish, with few white wool and bristly, hidden among the spines, bursting when ripe.

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) Backeberg, Curt "Das Kakteenlexikon" p. 70, 1966
7) Pilbeam, John "Rebutia" (ISBN 0-9528302-2-1)

Cultivation and Propagation: Rebutia archibuiningianaSN|4932]]SN|5051]] is a summer grower species that is easy to cultivate and recommended for beginners. The whole Rebutia fiebrigiiSN|5051]]SN|4932]] complex has delightful flowers and the plants remain compact, and clumps can easily be managed by division. Another advantage is that the plants are cold hardy in winter if kept dry.
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: It is better that they are repotted regularly. Pots should be only slightly larger than the plant and root system. 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 an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame or outdoor in a rockery.
Pests & diseases: All, especially the young, are susceptible to red spider mites.
Rot: This species is particularly easy and accommodating, seldom suffer of cryptogamic diseases. 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, 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! 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.