Gymnocalycium Pfeiffer ex Mittler (1844)

(Greek gymnos = naked, Greek kalyx = calyx)
naked flower calyx
because of the calyx without spines, bristles and hairs

usually flat globular, in age some thick columnar, very different sizes, simple or clumping
ribs 20 or less; spines adjacent or outspread, thin to very strong
flowers small short to large funnel shaped, often white or white with red center, however also yellow or red,
calyx bare and scaly; fruits and seeds very different

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Distribution

south America - Bolivia, Paraguay, south Brazil to Argentinia
almost complete south America eastern of the Cordilleras
steppes and mountains

Growth period

warm and part shady, avoid full sun, temporarily a location outdoor is possible
plants with stronger spines can get more sun
from early summer abundant watering, but standing moisture is to avoid
especially at warm weather not to sparse moisture

Winter period

bright and cool, not to dry, at 6–12°C (42–53°F), as possible not under 5°C (41°F)
mountain species occasionally also colder

Substrat

nutrient rich, very permeable to water with addition of peat
   
Gymnocalycium nigriareolatum Backeberg (1934)
 
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Habitat

Argentinia
Catamaraca - Sierra de Graciana

Description

black areole Gymnocalycium
broadly spherical, to about 5.9 in (15 cm) Ø, velvet blue green, simple
ribs 10, middle broad, tubercles longish padded, sharp edged, with small chin
areoles young somewhat ragged, yellow brown felted, at the age large, longish, black
spines initially yellow at the tip

7–8 radial spines, to 1.2 in (3 cm) long, sometimes somewhat bended, pink gray
1 central spine, somewhat longer
flowers slight bell shaped, porcelain white, outside greenish

Synonyms

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CITES

Appendix II
 
Description of "Kakteen von A bis Z" by Walter Haage with courtesy by Kakteen-Haage made available.

 

 

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