Horticulture Principles and Practices

14.7.1 WHAT ARE CACTI?
14.7 CACTI
Cacti (plural for cactus) are mostly succulent plants that belong to the family Cactaceae.
They differ from other succulents by having areoles that frequently carry spines and also
are sites of flower production. There are two kinds of cacti—desert cacti and jungle
cacti—each with its own growth requirements. Desert cacti are adapted to drought conditions
(xerophytic), largely because they lack leaves or have greatly reduced leaf structures,
thereby eliminating or minimizing stomatal transpiration. The stems of desert cacti
are columnar or spherical in shape and also are ribbed. Most of them have spines that are
often prickly (Figure 14–14). Jungle cacti, on the other hand, are generally epiphytic and
adapted to humid and shady conditions. Their stems are often flattened and cylindrical
structures. Jungle cacti lack ribs on their stems, which are jointed into long strings
(Figure 14–15). Their stems and spines are not prickly.
Desert cacti have more aesthetic appeal than jungle species in their vegetative states.
However, cacti, under proper conditions of light, produce attractive flowers, the finest and
largest ones being produced by jungle species. Because the jungle species
are adapted to shady conditions, they are better suited to indoor use. However, because of their
stringy stems, they often require staking or physical support in cultivation. They also do well
as hanging basket plants. Common cacti suited to indoor cultivation are listed in Table 14–3.
(a)
(b)
FIGURE 14–14 Desert cacti occur in a wide array of shapes, sizes, and forms. (Source: George Acquaah)
Cylindrical Nonsegmented Segmented
FIGURE 14–15
Basic stem types occurring in jungle cacti.
14.7 Cacti 461