S.K. Maiti, patron of Bidhannagar

Horticultural Society and a civil engineer residing in FC Block, offers guidance on choosing cacti to suit Salt Lake’s soil and climate

Cacti and other succulents are some of the hardiest plants worldwide. They are easy to care for, do not require much watering and can survive indoors and outdoors. Most of all, they look distinctive, imposing and are a plant of choice for many a green thumb.

What makes a cactus

Broadly defined, a succulent is a plant that is capable of withstanding long periods of draught. Nearly 50 families of succulent plants, including cacti, have highly specialised anatomy to survive prolonged draughts and almost all these plants manufacture food and water essential for this period.

The word “succulent” comes from the Latin word succos, meaning juice. These plants are able to store moisture in fleshy tissues in their stems, roots or leaves and most have developed distinctive features to help reduce water loss and withstand hostile environments.

They can also cease active growth and become dormant when necessary. Cacti belong to the succulent family but are distinguishable from other succulents due to certain distinctive features that will be discussed latter. Hence the saying: “all cacti are succulents but all succulents are not cacti”.

Origins of succulents

Cacti grow in deserts, is it? But they have also been spotted in wastelands, mountain tops, jungles and near oceans. So contrary to popular belief, succulents and cacti do not inhabit only deserts. The deserts of the world contain most — but by no means all — succulents.

These plants have a rich range of habitat. Many succulents developed in the snow-clad Alpine regions of Europe where they are adjusted to strong winds and poor rocky soils. From the tropical jungles of central and South America came another kind of succulents — Epiphytes. These are plants that naturally grow upon another plant but do not take any nourishment from them. They are not parasites. Tree-dwelling species collect nourishment and moisture from the surrounding moss and bark.

Some desert cacti can endure high temperatures, scorching days and freezing nights. Although a few can survive for years at a stretch and live in deserts with scanty rainfall round the year, most grow in semi-desert areas that receive sporadic rainfall between draughts.

Here rainfall is sometimes augmented by heavy dew and coastal mists. Even in the cool Atacama desert of Chile bordering the Pacific Ocean, a rare rainfall can stimulate the growth of succulents. These plants flower rapidly and set seed before returning to a semi-dormant state.

Desert cacti and succulents have the capacity to conserve moisture and withstand draughts by becoming dormant, and inducing new growth during favourable conditions. Cactus growers follow this growth pattern by keeping the plants dry in their dormant period (in Salt Lake this translate to winter) and watering them in the growing season.

In mountainous deserts, weather conditions vary dramatically with change of altitude. On high peaks, plants are exposed to intense sunlight and night time temperatures can dip to as low as -20°C along with fierce winds and snow.

Often there is no rain but the plants gain moisture from melting snow. Only small globular or creeping cacti and other succulents can survive in such conditions. Again on dry overcast foothills below the clouds, small cushion cacti predominate.

In mountainous regions, as a shield from harsh cold and bright sun, many cacti have a dense coat of woolly spines and succulents have developed thick waxy skins.

Although most cacti and succulents grow in arid deserts and mountainous regions, many species inhabit subtropical and tropical rain forests such as those in central and South America, Africa and the West Indies. Climate conditions in these areas are hot and humid and sunlight is filtered through thick tree canopies.

Cacti and succulents receive moisture from the atmosphere and regular rainfall, so here they have to survive with little sunlight, rather than little water. In artificial cultivation by growers, these plants best grow in humid light and shade.

In northern Australia, some jungle cacti like Epiphylum and some succulents like Hoya grow as Epiphytes.

There is practically no area in the world where some form of cacti and other succulents have not survived. Almost any type of environment and location is conducive to raising cacti and other succulents. Success depends merely on choosing the right species.

• To be continued