Publication: Addisonia 3: 5, pl. 83. 1918
Description
Gymnocalycium mostii is a solitary cactus species with a flattened dark green stem usually less than 13 across. The ribs are broad and obtuse with a small sharp chin below each tubercle. The horn-coloured spines take a nice red colouring when wetted. Its pale rose-pink blooms are profusely produced during the growing season.
Derivation of specific namae: The specific epithet honours the plant collector Carlos Most, who collected in Argentina.
Stem: Depressed-globose, 6 to 7 cm high, 13 cm in diameter, dark to bluish green.
Ribs: 11 to 14, vertical or slightly spiralled with age, broad and obtuse, deeply notched, with prominent, well defined tubercles.
Areoles: Roundish or elliptical, 6-8 mm long, with creamy-white wool when young, almost bare as they ages.
Spines: Strong, subulate, yellowish-brown or horn-coloured, darker brown and glossy at base and tips, becoming grey with age, stout, curving toward the stems; radial spines 7 to 9(-11), unequal, 6 to 22 mm. long; central spine solitary (occasionally 2), 18 to 20 mm Long.
Flower: Campanulate, rose pink, 6 to 8 cm broad. Tube short and thick, shining bluish green, with 8 to 10, semicircular, pale edged scales. Perianth-segments spreading pale rose pink with darker base, oblong.
Fruits: Ovoid to almost spherical, slate blue-green, to 2 cm long and 1.5 cm in diameter.
Seeds: Roundish, 0.7-0.9 mm, dark-reddish-brown to black, matt, with whitish hilum.
Origin and Habitat
Gymnocalycium mostii has a wide range, in Argentina (Córdoba).
Altitude range: 500 to 1,500 metres above sea level.
Habitat and Ecology: This cactus species grows on outcrops in chaco forest, and in grasslands. The species is extremely abundant and there are no major threats, the species is locally collected but this does not affect the population.
Cultivation and Propagation
Gymnocalycium mostii is a summer grower species that offers no cultivation difficulties. Water regularly in summer ( but can handle excessive water to few water) Keep this plant almost dry in winter at a minimum temperature of 0°C, prefer relatively rich substrate and low pH compost (if possible not limestone) otherwise growth will stop altogether. Feed with a high potassium fertilizer in summer. It is quite frost resistant if kept dry (Hardy to -12C). This plant needs plenty of space for its roots, repotting should be done every other year or when the it has outgrown its pot. This species is particularly easy and accommodating, seldom suffer of cryptogamic diseases.
Sun Exposure: Light shade. It may tolerate bright situations 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.
Propagation: Direct sow after last frost. (seldom produces offsets)
Seed Collecting: Permit fruit to ripen. Fruit must be significantly overripe before harvesting seed; clean and dry seeds.
Bibliography
Major references and further lectures
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N. L. Britton, J. N. Rose “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume 3, The Carnegie Institution of Washington, Washington 1922
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Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
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David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. “The New Cactus Lexicon” dh books, 2006
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Curt Backeberg “Die Cactaceae: Handbuch der Kakteenkunde” Gustav Fischer Verlag, Stuttgart New York 1982–1985
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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
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Demaio, P. & Trevisson, M. 2013. Gymnocalycium mostii. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 14 March 2015.
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Schumann & Guerke, “Blühende Kakteen” 2: pl. 93 1907
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Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Birkhäuser page 158. 2004
From llifle page Gymnocalycium bicolor
Origin and Habitat
Argentina Northeast (Córdoba)
Source: Gymnocalycium bicolor, LLIFLE - Encyclopedia of living forms, CC-BY-SA, retrieved 2026-10-25.
From llifle page Gymnocalycium valnicekianum
Description
They have been described as solitary, but they can also form groups with age. The plants in habit are each one different from its neighbours! Some has strong spines others weak, curly, straight, long or short ones and in all different combinations.
Stem: Usually globular up to 30 cm tall and 18cm across. Grass green to olive green.
Roots: Fibrous.
Ribs: About 9-12 which consist of flattened protuberances, each of which finishes with a large elliptical, densely furred areola length 12 mm.
Radial spines: 9-15 (-20) up to 4 cm long; Varying from brownish to grey, but those near the apex are mostly reddish-brown.
Central spines: 4-6 (-11) resembling the radial ones.
Flowers: White with a reddish throat. The diameter and length are identical and are equal to 5 cm. Seedlings bloom at the age of 5-7 years.
Remarks: Seems to be a pretty variable plant you might get some other names which are effectively the same plant and also not sure all plants identified as this are really this.
Origin and Habitat
Córdoba, Argentina.
Type locality: Sierra de Ischilin, prope Santa Catalina, 850 m, Córdoba (Argentina).
Altitude range: 600-1200 metres above sea level.
Habitat: This plant grows among hight grasses in the mossy cracks and cavities in rocky cliffs and in bushy hills.
Bibliography
Major references and further lectures
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Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
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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
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David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. “The New Cactus Lexicon” dh books, 2006
Source: Gymnocalycium valnicekianum, LLIFLE - Encyclopedia of living forms, CC-BY-SA, retrieved 2026-10-25.
From llifle page Gymnocalycium genseri
Description
Gymnocalycium mostii var. genseri is a small single headed, flattened cactus, very similar to Gymnocalycium mostii subs. valnicekianum. It distinguishes for the peculiar glaucous green body (usually dark green in G. valnicekianum) and for the thinner spines, all the other characteristics are identical, namely size and form of ribs, number of spines, colour of flowers etc.
Habit: It has been described as solitary, but in cultivation it can also form groups with age.
Stem: Usually globular up to 30 cm tall and 18 cm across, pale glaucous green.
Roots: Fibrous.
Ribs: About 9-12 which consist of flattened protuberances, each of which finishes with a large elliptical, densely furred areola length 12 mm.
Radial spines: 9-15(-20) up to 4 cm long; Varying from brownish to grey, but those near the apex are mostly reddish-brown.
Central spines: 4-6(-11) resembling the radial ones.
Flowers: White with a reddish throat. The diameter and length are identical and are equal to 5 cm. Seedlings bloom at the age of 5-7 years.
Origin and Habitat
Sierra Ischilin, Argentine province of Córdoba. This species is known only from the Sierra Ischilin range and a few adjacent areas and can be considered a microendemic species.
Altitude: (150-)900-1150
Habitat: It occours on rocky soils, filled up with weathered material and gravel often in association with Gymnocalycium parvulum ssp. agnesiae among grasses and under bushes. The plants are sometimes almost covered by Selaginella.
Cultivation and Propagation
Gymnocalycium genseri is a summer grower species that is easy to cultivate.
Growth rate: It is a slow growing and easily flowering species.
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: This plant needs plenty of space for its roots, repotting should be done every other year or when the it has outgrown its pot. Use pot with good drainage.
Watering: Needs moderate to copious waterings in summer, but do not overwater (Rot prone), keep dry in winter at a minimum temperature of 0°C.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: Reputedly resistant to frost if kept on the dry side prior to, and during, cold weather (hardy to -12 C ° C, or less for short periods), but for safe cultivation it is best to avoid freezing temperatures.
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: 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: This species is particularly easy and accommodating, seldom suffer of cryptogamic diseases. Rot it is only a minor problem with gymnocalyciums if the plants are watered and “aired” correctly. If they are not, fungicides won’t help all that much.
Propagation: 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!
Source: Gymnocalycium genseri, LLIFLE - Encyclopedia of living forms, CC-BY-SA, retrieved 2026-10-25.
Cultivars and forms (4)
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