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Origin and Habitat: Sierra Ambato, Catamarca (and La Rioja?), Argentina. This species has a very small range (extent of occurrence is 1,500 km2) and occurs in only two locations however there might be more subpopulations in the area.
Altitude range: It occurs at elevations of 800-1800 metres above sea level.
Habitat and Ecology: The species grows in high altitude grasslands. The major threat is intentional fires in the grasslands. The species is threatened in part of its range by collectors.
- Gymnocalycium oenanthemum Backeb.
Gymnocalycium oenanthemum Backeb.
Kaktusář 1934, August; cf. Backeb. Blatter Kakteenforsch. 1934, Pr. 9, [p.2].
- Gymnocalycium oenanthemum Backeb.
- Gymnocalycium oenanthemum subs. carminanthum (Borth & Koop) H.Till
- Gymnocalycium carminanthum Borth & Koop
- Gymnocalycium tillianum Rausch
- Gymnocalycium tillianum subs. montanum (Slaba) F.Berger
Description: Gymnocalycium oenanthemum is a beautiful solitary stemmed species, of modest size, with stout spines slightly curved inward and particularly attractive for its beautiful wine-red or deep salmon-pink flowers.
Taxonomy: In the past the name G. oenanthemum was reserved to the plants found in the south-east slope of Sierra Ambato while those on the west slope of the valley was classified as Gymnocalycium tillianum, at the same time the carmine red flowering form growing from 1300 to 1800 m was named Gymnocalycium carminanthum, but apart little differences in seeds morphology this three plants are the same and not readily distinguishable. The white flowering Gymnocalycium ambatoense may also be referred to the same species. The absence of the central spine is a good clue of G. oenanthemum (but not always true)
Stem: flattened globose, dull grey-green to to bluish green, 6-8(-10) cm high and 7-9(-12) cm in diameter.
Ribs: (6-)11-13, broad. obtuse, sharply angled.
Central spine: Usually absent, sometimes one erect.
Radial spines: Usually 5(-7), reddish grey with dark tips, stout, straight to slightly curved inward, to 1.5-2 cm long, pinkish at first, later grey.
Flowers: Wine red or deep salmon-pink, shiny, to 5 cm long and 4-4.5 cm in diameter lasting approx 4 days..
Fruits: Ovoid, green.
Seeds: 0.8 mm in diameter, dark brown to black, tuberculate, with small pale hilum.
Subspecies, varieties, forms and cultivars of plants belonging to the Gymnocalycium oenanthemum group
- Gymnocalycium ambatoense Piltz: has white or pinkish blooms and thinner spines. It is intermediate between Gymnocalycium oenanthemum and Gymnocalycium hossei. Distribution: Sierra Ambato 900-1100 m asl.
- Gymnocalycium oenanthemum Backeb.: (var. oenanthemum) has wine-red or deep salmon-pink flowers with stout spines slightly curved inward. Distribution: South-east slope of Sierra Ambato.
- Gymnocalycium oenanthemum subs. carminanthum (Borth & Koop) H.Till: has pink-red to bright carmine-red flowers. Distribution: Sierra Ambato from 1300 to 1800 m asl.
- Gymnocalycium tillianum Rausch: almost identical to the standard G. oenanthemum, with only little differences in seeds morphology. Distribution: West slope of Sierra Ambato.
Bibliography: Major references and further lectures
1) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
2) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
3) Roberto Kiesling, Omar E. Ferrari “Cien cactus argentinos” Editorial Albatros, 2005
4) 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
5) Hans Krainz “Die Kakteen: eine Gesamtdarstellung der eingeführten Arten nebst Anzucht- und Pflege-Anweisung” Franckh'sche Verlagshandlung” Lfg. 59. 1974
6) Demaio, P., Perea, M. & Trevisson, M. 2013. Gymnocalycium oenanthemum. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 08 August 2014.
7) Blätter für Kakteenforschung 1934. Nummer 9, S. , 1934, Genus 74, Species 4.
8) Zuloaga, F. O., O. N. Morrone, M. J. Belgrano, C. Marticorena & E. Marchesi. (eds.) 2008. Monogr. Syst. Bot. Missouri Bot. Gard. 107: 3 Vols., 3348 p.
Cultivation and Propagation: Gymnocalycium oenanthemum is an easy to grow succulent, more cold tolerant than most and less fussy regarding soil conditions.
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.
Repotting: Use pot with good drainage.
Watering: Water regularly in summer, but do not overwater (Rot prone), keep dry in winter.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: Reputedly somewhat 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).
Exposition: Outside bright but 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.
- Sciara Flies: Sciara flies are one of the major problems for seedlings. It is a good practice to mulch your seedlings with a layer of grit, which will strongly discourage the flies.
- 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.
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