Overview: The Rock Garden is home to many plant species that have adapted to survive in hot, dry environments. Although the Florida peninsula is sunny and hot and its soils are sandy, the frequent rains, particularly in the winter months, create an environment that is inhospitable to most cacti and succulents. The species displayed in the Rock Garden are, for the most part, are exceptions to this rule.
A Closer Look: There are three principal features that characterize plants adapted to dry environments. The first is a water-storage capability. Many plants employ their leaves for this function while other, such as cacti, store water in the cells of their stems. In extremely severe environments, many species’ water storage parts, whether leaves or stem, have become spherical to maximize their effectiveness.
A second unifying feature of desert plants is armament of some sort to protect these water stores from dismemberment by thirsty herbivorous animals. In cacti,
the leaves have been modified into spines; in aloes spines have been derived from serrations on the leaf margin. In crown of thorns, spines occur in pairs because they evolved from paired leaflike structures called stipules that arise from the stem at the base of a leaf.
A third common feature is relatively great longevity. There are no annuals in desert environments - only longlived perennials. This is attributable to the fact that these plants’ seeds, like all seeds, require moisture for germination. Since water is not usually available while seeds are viable, many years’ seeds may not germinate. Natural selection has produced species long-lived enough to ensure that their seeds will be produced year after year until finally a rainy season coincides with seed release and a new generation of the species appears.