Mammillaria pilcayensis is a species of cactus in the genus Mammillaria, which is known for its diverse range of small, often clustered, globular cacti. Here’s a detailed look at Mammillaria pilcayensis:

Botanical Description:

• Size and Shape: Mammillaria pilcayensis is a small, globular cactus that typically reaches a height and diameter of about 5-10 cm (2-4 inches). It can form clusters over time, with multiple stems growing closely together.

• Ribs and Tubercules: The cactus features pronounced, rounded tubercles arranged in spirals around the stem. The tubercles are covered with small, fine spines.

• Spines: The spines of Mammillaria pilcayensis are generally short and can range in color from white to pale yellow. They are arranged in clusters on each tubercle, providing a dense, somewhat woolly appearance.

• Flowers: The plant produces small, funnel-shaped flowers that typically emerge from the areoles at the top of the cactus. The flowers are usually pink to reddish in color and are relatively small but quite attractive. They generally bloom in late spring or early summer.

• Fruit: After flowering, Mammillaria pilcayensis produces small, round fruit that can be covered in spines or fine hairs. The fruit contains seeds that can be used for propagation.

Habitat and Cultivation:

• Native Range: Mammillaria pilcayensis is native to Mexico, specifically the region of San Luis Potosí. It grows in arid and semi-arid environments, often on rocky slopes or in scrubby areas.

• Soil: It thrives in well-draining soil. A standard cactus mix or a mix of potting soil with sand and perlite is ideal to ensure good drainage and prevent root rot.

• Watering: Water moderately during the growing season (spring and summer), allowing the soil to dry out between waterings. In winter, reduce watering significantly as the plant goes into a semi-dormant state.

• Light: Provide bright, indirect light to full sun. In regions with intense sunlight, some shading during the hottest part of the day might be beneficial to avoid sunburn.

• Temperature: Mammillaria pilcayensis prefers temperatures between 20-30°C (68-86°F) during the growing season. It can tolerate cooler temperatures in winter but should be protected from frost.

• Fertilizing: Use a diluted cactus fertilizer during the growing season to promote healthy growth. Avoid over-fertilizing, which can lead to excessive growth and reduced flowering.

Propagation:

• From Seeds: The most common method of propagation is from seeds. Sow seeds in a well-draining soil mix and keep them warm and slightly moist until they germinate. Seedlings should be handled carefully to avoid damage.

• Offsets: Mammillaria pilcayensis can also be propagated from offsets or pups if they are produced. Separate the offsets from the main plant and let them callous over before planting them in fresh soil.

Common Issues:

• Overwatering: Overwatering is a common problem, leading to root rot. Ensure the pot has good drainage and let the soil dry out between waterings.

• Pests: Watch for common cactus pests such as spider mites, mealybugs, and scale insects. Regular inspection and treatment can help manage these pests.

• Disease: Fungal infections can sometimes affect cacti, causing discoloration or soft spots. Good air circulation and proper care can help prevent these issues.

Mammillaria pilcayensis is a charming and relatively easy-to-care-for cactus species, making it a good choice for both beginners and experienced collectors. Its compact size and attractive flowers make it a delightful addition to any cactus collection.