From the Greek myrtillos, the diminutive of the word for myrtle, in reference to the small fruit (Cactaceae). These are greenhouse succulent plants from the Americas, formerly included in the genus Cereus. They have strong, upright stems with six to eight ridges and stiff spines. Unlike most cacti, anything up to ninecan form each areole.
- cochal, stems pale bluish when young, but the colour darkens with age. sometimes considered to be only a variety of M. geometrizans, California. M. eichlamii, dark green stems, areoles woolly where the flowers are produced, Guatemala. M. geometrizans, blueish-green stems, edible fruit. often grown as hedge, Mexico. M. pugionifer, very blue stems, Mexico. All have creamy-white diurnal flowers.
A fairly rich but porous compost suits these plants best, and a suitable one would be an average potting compost with 1/5 part added of coarse sand or broken brick. Repot in April or May in pots large enough to support the plants if they grow tall. Water during spring and summer as often as thedries out, but keep the soil quite dry during winter, when a minimum temperature of 55 °F (13°C) should be maintained. In the growing season they require a temperature of 65-80 °F (18-27°C). Give them a sunny position in the greenhouse.
Propagation is by seed sown in a good seed compost in pans in February-March, in a temperature of 70 °F (21°C). Prick out the seedlings when they are large enough to handle. These cacti can also be propagated by offsets which can form at the base of the plant or from the top of a beheaded plant, and which are rooted when the base is dry, in a compost of sand and peat.