Melocactus azureus var. krainzianus
M. azureus is native to the Northeast of Brazil
M. azureus is a dwarf cactus belonging to the Cactaceae botanical family. The plant has a small and spherical stem, blue glaucous in color and filled with spines. The stem can reach up to 15 cm in diameter and in height and is arranged in ribs divided by furrows. Spines are long, greyish and pointed and are positioned on the areolas. Areoles are whitish and placed along the edge of the ribs. At the top of the stem there is the cephalium. The cephalium is a woolly and bristly outgrowth, usually brightly colored and from which flower buds are formed. The cephalium is typical of some genera such as Melocactus and Discocactus and in some species it can reach a height of 1 m. The cephalium is useful for defending the plant from animals but it has no chlorophyll so it cannot photosynthesize. In this species the cephalium is globose, cylindrical, short, whitish in color and with brownish bristles and usually 10 cm high. Flower, borne at the top of the cephalium, are small, magenta and self-fertile.
This is a demanding cactus that requires attention, so it is recommended for experienced growers. The best sun-exposure is direct sunlight, and the plant does not like temperatures below 10 °C so it needs to be placed indoors during the coldest period and outdoors in the hottest one. The plant does not tolerate severe changes in temperature. The soil should be mixed with pumice, clay and loam to allow the drainage and prevent the root rot, the plant is prone to it indeed. Remember to use perforating pot to drain excess water. Watering can be done regularly from April to October: during the vegetative period you can water the plant (every 7 days), checking that the soil is completely dry before watering again; in winter you should stop the watering to allow to the plant to enter dormancy. About fertilization, for this plant is sufficient to fertilize once a year during the growing season with the specifics fertilizers for succulents. Until the cactus does not emit the cephalium it can be repotted every year in a pot 2 cm wider than the previous one. After the release of the Cephalium, the plant can only be repotted when the pot is too small. Repotting should be done early in the growing season with fresh new potting soil.
Propagation can only be done by seed. By seed is very simple to propagate the plant, it is enough to sow the seed in a sandy loam soil and keep it with high level of humidity; temperatures of germination are between 20 and 28 °C. Be careful not to exceed with watering and not to cause radical rot. After the release of the Cephalium, you should decrease watering.
The name Melocactus comes from the Latin “malus” which means apple. This genus was one of the first to be found by Christopher Columbus and the name refers to the cephalium which resembles an apple.
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