Origin and Habitat: Cordoba and San Luis provinces, northern Argentina.
Altitude: Grows in the highest parts of the Sierras Grandes of Córdoba, between 1500 and 2000 m above sea level.
Habitat: They grow in rock crevices but also in rich humus areas among grasses. The climate is quite humid with frequent rainfall or mist throughout the year and winter snowfall.

• Gymnocalycium andreae (Boed.) Backeb. & F.M.Knuth
• Echinocactus andreae Boed.

• Gymnocalycium andreae (Boed.) Backeb. & F.M.Knuth
• Echinocactus andreae Boed.

• Gymnocalycium andreae subs. carolinense Neuhuber
• Gymnocalycium bruchii subs. carolinense (Neuhuber) Papsch
• Gymnocalycium carolinense (Neuhuber) Neuhuber
• Gymnocalycium carolinense var. eltrebolense Neuhuber
• Gymnocalycium carolinense subs. fedjukinii V.Gapon & Neuhuber
• Gymnocalycium carolinense subs. ludwigii Neuhuber
• Gymnocalycium bruchii subs. ludwigii (Neuhuber) Papsch

• Gymnocalycium andreae var. fechseri H.Till
• Gymnocalycium andreae var. doppianum H.Till & R.Kiesling
• Gymnocalycium doppianum Mereg.

Description: Gymnocalycium andreaeSN|10579]]SN|10579]] is a low growing prickly cactus barely rising above ground level, usually solitary in habitat, but often branching basally in cultivation to form clusters to 15 cm or more wide. This species is different from the general run of gymnocalyciums in the colour of its flowers, in this case a brilliant sulphur-yellow.
Root: Large taproots.
Stem: Spherical or hemispherical, usually depressed at apex, up to 5 cm in diameter dark bluish-green or black- green with a touch of bronze.
Ribs: 8 to 13, straight, flattish, divided into prominent, rounded tubercles, with sharp cross-furrows. Chinlike protrusions absent.
Spines: 9-13, weak, all 1-1,5 cm long (or less).
Radial spines: Thin, spreading, 6(-9) lateral and 1 descending, similar to the centrals, dull white or yellow-white, with a chestnut base.
Central spines: 1-3, slender, needle-like often somewhat curved upward, rough, dark brown.
Flowers: Bell-shaped to funnel-shaped, 2,5-4 cm long and up to 5,5 cm in diameter at anthesis, bright satiny-yellow. Tubeless or with a very short tube. Outer perianth segments pale greenish yellow with darker green mid-stripe outside. Inner perianth segments clear sulphur-yellow, narrow to almost spatulate. Style with about 8 stigmatic lobes. Anther yellow.
Blooming season: Flowers are borne in early summer.
Fruits: Globose to cylindrical, blue-green, approx. 1,2 cm in diameter.
Seeds: Black opaque.
Remarks: It is clearly related with Gymnocalycium bruchiiSN|14835]]SN|14835]], which grows in the same area but generally at lower altitude: apparently they don't form hybrids. The similarities between them are observed in the seeds, in the early flowering, shape and dehiscence of fruits and also in their small size. Gymnocalycium bruchiiSN|14835]]SN|14835]] shows a short floral tube, while Gymnocalycium andreaeSN|10579]]SN|10579]] is almost tubeless.

Bibliography: Major references and further lectures
1) Peter Chapman, William Davidson, Margaret Martin “An illustrated guide to popular houseplants” Salamander, 1987
2) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
3) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
4) Roberto Kiesling, Omar E. Ferrari “Cien cactus argentinos” Editorial Albatros, 2005
5) 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
6) Curt Backeberg “Die Cactaceae: Handbuch der Kakteenkunde” Gustav Fischer Verlag, Stuttgart New York 1982–1985
7) John Borg “Cacti: a gardener's handbook for their identification and cultivation” Blandford Press, 1959
8) Hans Hecht “Cacti & succulents” Sterling Pub. Co., 1997
9) Erich Götz, Gerhard Gröner: “Kakteen: Kultur, Vermehrung und Pflege. Lexikon der Gattungen und Arten.” Ulmer, Stuttgart 1984.
10) 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

Cultivation and Propagation: Gymnocalycium andreaeSN|10579]]SN|10579]] is a summer grower species that is easy to cultivate. It is one of the most cold-tolerant South American species. It can grow outdoors and is hardy to -15° C or even less.
Growth rate: It is a relatively rapidly growing and easily flowering species that will make clumps given the best conditions.
Soils: It likes very porous standard cactus mix soil. Prefer a low pH compost, avoid substrata rich in limestone; otherwise growth will stop altogether.
Repotting: Use pot with good drainage.
Watering: Needs moderate to copious waterings in summer, but do not overwater (Rot prone), keep dry in winter.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: Reputedly very resistant to frost if kept on the dry side prior to, and during, cold weather (hardy to -15 C ° C, or less for short periods).
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.
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: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for:
- Red spiders: Red spiders may be effectively rubbed up by watering the plants from above.
- Mealy bugs: Mealy bugs occasionally develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects.
- Scales: Scales are rarely a problem.
- Rot: Rot it is only a minor problem with cacti if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much.
Propagation: Division, direct sow after last frost. 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.