Adapting to survive
The succulents and cacti in the Dry Temperate Zone are grown for their strong shapes, fleshy and prickly textures and for their brilliantly coloured flowers. These features, developed for survival, make them strikingly beautiful plants to grow.
Humans use them in many ways. For example, tequila is made from Agave, and Aloe vera is an ingredient in many toiletries.
Drawings of cacti have been found among Aztec remains and Tenochtitlan (the old name of Mexico City) means 'place of the sacred cactus'. The national coat of arms of Mexico includes a cactus. Christopher Columbus (1451-1506) brought the first cactus (Melocactus) to Europe.
To survive dry conditions, cacti and succulents store water in their leaves, branches or stem bases. The word succulent comes from the Latin succos, meaning juice. Cactus leaves are usually small or reduced to spines. A small surface area limits the quantity of water that can evaporate and be lost to the plant.
Spines also collect dew at night and drip it onto the ground where the roots can absorb it. They also protect the plant from animals that fancy a nibble!
As UK summers get warmer, more succulents can be grown outside. At Wisley, there are aloes planted in the Walled Garden as well as the magnificent specimens in the Glasshouse.
Today, one of the principal uses for cacti is as a host for the cochineal insect, from which a red dye (carmine) is obtained.