All the information and photos in cactus art file are now available also in the new the Enciclopedia of Cacti. We hope you find this new site informative and useful.

This is one of the largest growing and the heavier spined specie in the gymnocalycium group.
 

Description: Description:  They have been described as solitary, but they can also form groups with age.
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.

Note: 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.
 

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Conservation status: Listed in CITES appendix 2.

Gymnocalycium valnicekianum Jajo 1934 (valniceckianum)

Accepted Scientific name:  Gymnocalycium mostii (Gürke) Britton & Rose 1918

Origin & habitat: Argentina (Córdoba) This plant grows among hight grasses in the mossy cracks and cavities in rocky cliffs.
The plants in habitat are each one different from its neighbours! Some had strong spines others weak, curly, straight, long or short ones and in all different combinations.
 

Large white flowers with a reddish throat from mid spring to early summer.

Cultivation: It 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)
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. 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.

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

Photo of conspecific taxa, varieties, forms and cultivars of plants belonging to the Gymnocalycium mostii complex (This Taxon has lots of synonyms ( like many other cacti) whit several controversial varieties and subspecies ):

• Gymnocalycium ferox var. ferocior (G. mostii ssp. ferocior)
• Gymnocalycium valnicekianum (G. mostii)

All the information and photos in cactus art file are now available also in the new the Enciclopedia of Cacti. We hope you find this new site informative and useful.