Melocactus

Family Cactaceae. The genus includes 33 species found on the coasts of Mexico, as well as in the interior regions of Guatemala, Honduras, Peru and northern Brazil.

Melocacti form a solitary stem of medium size, from depressed-globose to short-cylindrical in shape, with well-defined wide and high ribs and strong awl-shaped, straight or curved spines. Melocacti differ from other genera by the presence of a peculiar inflorescence — the cephalium — a generative shoot at the apex of the stem. The cephalium has no chlorophyll and no stomata for gas exchange in the surface tissues, is very densely covered with bristles and hairs, and is intended exclusively for flowering and fruiting; it is absent in young plants.

In general, melocacti are so uniform that their monophyly (descent from a common ancestor) is beyond doubt.

Melocacti, widely distributed in the Antilles, apparently were the first large globose cacti encountered by Europeans upon the discovery of the Americas.

Pollination is ornithophilous (mainly by hummingbirds), although visits by bees and other insects have also been recorded. Most species of melocacti (with the exception of the self-sterile M. azweus and M. glaucescens) exhibit self-fertility of flowers, which contributes to the wide distribution of melocacti, since even isolated single specimens can produce viable seeds.

Temperature: in winter not below 15 °C.

Lighting: bright sunlight; in the height of summer they can be shaded from direct sun.

Watering: reduced in winter, but not stopped completely.

Humidity: in summer regular spraying is required.

Soil: a mixture of turf and leaf mold soil, sand and crushed brick; good drainage is necessary.

Almost all cactus-growing books contain the warning to "beginners" to refrain from growing melocacti. This warning is caused by the fact that all melocacti originate from tropical and even equatorial regions, and therefore they do not tolerate the standard wintering conditions used, for example, for Mexican or Argentine cacti. In nature melocacti "winter", i.e. survive the dry season at elevated temperatures and under high levels of solar radiation. This is the opposite of how our "Mexican cacti" overwinter. Therefore the first rule when cultivating melocacti is to keep them at room temperature during their winter dormancy. A cold windowsill is completely unsuitable for melocacti. Of course, some hobbyists keep them in winter exactly on a cold windowsill together with other cacti. However, these same enthusiasts later admit that their twenty-year-old melocacti still have not formed a cephalium. If there is no space for melocacti deep in the room, they should be placed on a shelf in the upper part of the window opening (it is much warmer there than on the windowsill), and so that there is no nearby vent. The second condition for successful wintering of melocacti is supplementary lighting of the plants for several hours a day. And the third condition is not to water them.

Summer cultivation overall is not difficult. Plants must be placed in a greenhouse or cloche where the daytime air temperature will be no less than 30 degrees Celsius and the night temperature no less than 20 degrees. Heating should be provided even in summer for prolonged cold and cloudy periods, when even by day the temperature in your greenhouse does not reach the required level. If in summer you can ensure the required day and night temperatures, then you will have no problems growing melocacti. Most cacti in our culture respond well to intensified care during short autumn days. However, increasing watering and fertilizing in autumn is possible only with appropriate cultivation arrangements — equipped, if necessary, with artificial heating. The months August, September and October play an important role in cultivation. These are fast-growing cacti, very tolerant (like Echinopsis) of overwatering and consistently moist soils. Small species, such as Melocactus matanzanus, may begin forming a cephalium as early as four years after sowing. Soil is standard cactus mix.