Accepted Scientific Name: Gymnocalycium hybopleurum (K.Schum.) Backeb. in Backeb. & F.M.Knuth
Kaktus-ABC [Backeb. & Knuth] 289. 1936 [12 Feb 1936] Backeb., F.M.Knuth
Origin and Habitat: Catamarca and Cordoba, Argentina.
Altitude:400-2600
Habitat: It grows in various environs and elevations, among stones and bushes, often in association with Lobivia mazanensis and Tephrocactus sp.
Synonyms:
See all synonyms of Gymnocalycium hybopleurum
Description: Gymnocalycium hybopleurumSN|11445]]SN|15762]] is a strongly-spined and variable species related to Gymnocalycium multiflorumSN|15762]]SN|11445]], usually solitary in habitat, but occasianally branching basally in cultivation. This species is characterized by a marked variability in the length and shape of the spines and has received many names.
Stem: Hemispherical to globular in shape up to 15 cm tall and in diameter dark-green or blue-green.
Ribs: About 10-13, rounded or acute, with small chinlike protrusions.
Central spine: Absent or one, with darker tip.
Radial spines: 7-8, straight or slightly curved, thick and flattened, interwoven around the body up to to 3 cm long, dull creamy or pinkish coloured, later grey.
Flowers: Short-tubed, ivory white (occasionally pinkish) with a red throat.
Blooming season: Flowers are borne in early summer. It flowers quite readily as a young seedling.
Fruits: Globose to cylindrical, blue-green.
Subspecies, varieties, forms and cultivars of plants belonging to the Gymnocalycium hybopleurum group
Gymnocalycium curvispinum Frič: has strong curved spines. Distribution: Villa Dolores to Sierra Ancasti, Catamarca, Argentina.- Gymnocalycium curvispinum var. acuticostatum hort.: has strong curved spines and the very prominent acute chinlike protrusions on the ribs, and flowers often pink or orangish. Distribution: Catamarca, Argentina.
- Gymnocalycium hybopleurum (K.Schum.) Backeb. in Backeb. & F.M.Knuth: is a strongly-spined and variable species, usually solitary in habitat. Distribution: Catamarca and Cordoba, Argentina.
- Gymnocalycium nigriareolatum Backeb.: has solitary stems with large black areoles. The flowers are white, with a greenish to reddish throat. Distribution: around the town of Catamarca, Argentina.
- Gymnocalycium nigriareolatum f. carmineum H.Till: has reddish-pink flowers with a darker throat. Western slopes of the Sierra de Ancasti, Catamarca, Argentina.
- Gymnocalycium nigriareolatum var. densispinum Backeb. ex H.Till: the stem forms basal shoots. Distribution: Catamarca, north of the town near El Jumeal Reservoir, Catamarca, Argentina.
- Gymnocalycium nigriareolatum var. simoi H.Till: the radial spines are more or less pectinated. Distribution: Palo Labrado, south of La Merced, Catamarca, Argentina.
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, page. 41
5) Curt Backeberg “Die Cactaceae: Handbuch der Kakteenkunde” Gustav Fischer Verlag, Stuttgart New York 1982–1985
1) Clive Innes, Charles Glass “Cacti” Portland House, 01/mag/1991
Cultivation and Propagation: Gymnocalycium hybopleurumSN|15762]]SN|15762]] is a summer grower species that is easy to cultivate.
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: 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 -5 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, 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: 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.
