What do a 40-metre-high baobab and a ten-centimetre Haworthia in a pot have in common? They're both succulents. The reason they look so different is that succulents are not a botanical category in the strict sense of the term. The term refers to plants that can withstand prolonged drought.

Succulent comes from the Latin succulentus, meaning "full of juice". Succulent plants have this name because they store water in their roots, stems or leaves. They then transform it into a mucilaginous juice, drawing on these reserves when drought sets in.

The juice gives the stems and leaves a fleshy appearance. This is why succulent plants are sometimes called fat plants.

Water reserves enable succulents to survive in arid environments. They thrive in hostile environments, in the desert or at altitude. Succulents are native to the plains and mountains of southern Africa and South America.

To resist these extreme conditions and predators, succulents have developed ways of defending themselves. Some, like cacti, have replaced their leaves with thorns to avoid being devoured by herbivores. Others are covered with bloom, a thin waxy layer that protects them from heat and parasites.

There are over 12,000 succulent species. They are divided into different botanical families such as Crassulaceae, Cactaceae, Liliaceae, Asteraceae..

To create an outdoor rock garden of succulents, you can select hardy varieties of Agave (Agave havardiana and Agave montana), prickly pear (Opuntia), dwarf aloe (Aloe Aristata), orpins (Sedum), yuccas (Yucca filamentosa or Yucca gloriosa) or houseleeks (Sempervivum). They can withstand sub-zero temperatures, provided the roots are kept dry. If you live by the sea or in a region where it doesn't freeze, add a Delosperma and an Aeonium.

When your winters are harsh, grow your succulents indoors. Sansevieria (mother-in-law's tongues), Haworthia, Echeveria, Gasteria, Crassula, orchid cactus (Epiphyllum), Aloe vera and Euphorbia enjoy the warmth of our homes and require little maintenance. Some green plants, like Kalanchoe and Schlumbergera truncata (Christmas cactus), even bloom in winter.