The Astrophytum capricorne, commonly referred to as the Goat's Horn Cactus, is a distinctive species known for its star-shaped body and long, curved spines that resemble the horns of a goat. The 'crassispinum' variety of this species is notable for its especially thick and pronounced spines, adding to its unique appearance. Astrophytum capricorne crassispinum thrives in arid environments, adapting well to life in rocky and sandy soils where water is scarce.

The extremely rare white variegated form of Astrophytum capricorne crassispinum is a sought-after cultivar among cactus enthusiasts and collectors. Variegation in plants refers to the appearance of differently colored zones in the leaves, and in the case of cacti, on the body or stem, due to the lack of chlorophyll in some cells. This white variegation manifests as striking patches or stripes of white against the green body of the cactus, making each specimen unique.

Cultivation Tips:

1. Lighting: Astrophytum capricorne crassispinum, including its white variegated form, requires plenty of sunlight to thrive. However, in extremely hot climates, it benefits from partial shade during the hottest part of the day to prevent sunburn.

2. Watering: This species is drought-tolerant but requires regular watering during the growing season (spring to autumn). Allow the soil to dry out completely between waterings to prevent root rot. In winter, reduce watering significantly to mimic its natural dormant period.

3. Soil: A well-draining soil mix is crucial. Use a cactus or succulent mix, or make your own by mixing regular potting soil with sand and perlite or pumice to improve drainage.

4. Temperature: Astrophytum capricorne crassispinum prefers warm temperatures but can withstand cooler temperatures during its dormant period in winter. Protect it from frost to prevent damage to the plant.

5. Fertilization: Feed with a diluted cactus fertilizer during the growing season every 4-6 weeks to support healthy growth. Do not fertilize in winter.

6. Propagation: Propagation is typically done through seeds, as the variegated forms especially can be challenging to propagate through cuttings due to the lack of chlorophyll in some parts of the plant.

7. Pests and Diseases: Keep an eye out for common pests such as mealybugs and scale insects. Treat infestations promptly with appropriate insecticides or natural remedies. Overwatering and poor drainage are the primary causes of root rot, so ensure your watering and soil mix are well managed.

The white variegated form of Astrophytum capricorne crassispinum requires the same care as the standard form but may need slightly more protection from direct sunlight to prevent the variegated parts from scorching. Due to its rarity and unique appearance, it may also command a higher price and be more difficult to find in the trade. Collectors and enthusiasts often seek out these plants for their unique beauty and the challenge they present in cultivation.