Mammillaria elongata Cristata

Mammillaria elongata 'Cristata' is commonly called brain cactus due to its erect and creeping crested stems, tightly packed together in a convoluted mass. Short and crossing yellow radial prickers adorn its tough green epidermis in a dense, almost golden lace. Very resistant to heat and drought, it is a slow-growing plant that prefers full sun in well-drained, rocky to sandy and dry soil. Eventually, it forms a curious ground cover for rock gardens and banks in hot regions. Elsewhere, overwinter it in a bright, frost-free room.

Mammillaria elongata 'Cristata' or Mammillaria elongata f. cristata is a crested form of the elongated mammillaria or golden mammillaria that belongs to the immense family of cacti. Mammillaria elongata is a succulent perennial native to central Mexico where it forms ground covers over 1m (3ft) in size with its rapid growth and self-rooting stems. It grows in dense clumps of short, thick stems. Their golden appearance comes from their dense covering of short, yellow prickles, turned inward and gathered in radial clusters around pale-yellow to brown areoles. It is resistant to drought but does not survive the negative temperatures of our winters. Cultivate it in a pot outside hot regions, in full sun or partial shade in a very well-drained substrate made of a mixture of soil, sand, and gravel. Avoid overly humid environments or excessive watering.

Its crested form corresponds to an anomaly in the organisation of the cells responsible for its growth. Instead of forming regular cylindrical stems, the cactus stems will grow in width, forming sinuous and intertwined crests. Mammillaria elongata 'Cristata' has much slower growth than the species, forming a spreading clump only 15cm (6in) tall and 30cm (12in) wide. It forms several stems that are 3cm (1in) thick and 10cm (4in) wide, with a tough epidermis of medium green. Its surface is punctuated with pale-yellow to brown areoles, which gather short prickles, 1cm (0.4in) long, curved inward, organised in a circle and equipped with white hair in their youth. This plant blooms in May-June, producing a crown around the top of the stems. The small flowers measure 1cm (0.4in). They are white to pale-yellow or pink, and last up to two months. They sometimes bloom again later in the year. They are followed by tiny, elongated bright red fruits.

In warm regions, Mammillaria elongata 'Cristata' will find its place in a dry and sunny rockery or on a wild bank. Elsewhere, it can be planted in a pot that can be stored away at the arrival of the first cold weather. In containers, stop watering until the vegetation resumes in spring. It can be paired with other cacti such as echinocactus, ferocactus, and astrophytums to create miniature dry gardens or placed in a large pot to decorate a corner of a conservatory or a windowsill.