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         Description: Solitary, 
        slowly growing cactus, densely covered with 
        incredibly strong twisted spines 
        Stem: Grey green, compact, globular up to 12 (-15) cm wide 10 cm 
        tall in cultivation (in nature it is partially underground) with a 
        slightly concave woolly apex. Will not (usually)
        
        offset.  
        Spines: Long, stout, 
        eagle claw-shaped, typically-twisted, 
        up to 4 cm long. Black turning dark grey as they ages. 
        Flowers: Open petaled, funnel-shaped, 
        about 4(-7) cm in diameter, 3(-5) cm tall and pinkish in colour.  They 
        grow near the apex. The flowers of Gymnocalycium cardenasianum 
        have a tough time trying to force themselves through the fierce spines, 
        and is quite rare to see an open flower because the spines prevent the 
        flowers from opening properly. 
        Blooming season: They will bloom at an early age and bloom 
        sparingly in mid-summer 
        Cultivation: Keep this plant almost dry in winter at a minimum 
        temperature of 0°C. It prefers 
        a
        
        low pH
        
        compost; otherwise
        
        growth will stop altogether. The plant tolerates
        
        extremely bright situations (grow it hard, at a high position in the 
        greenhouse, to try and develop the spines, which are strong and twisted) 
        but it enjoys some shade during the hottest part of the day in summer. 
        
        
        Propagation: Seeds (seldom produces offsets) or grafting. 
        
        
          
        
        
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