Shade-tolerant Flowering Plants: Adaptations and Horti- Cultural Implications

It is quite difficult to select suitable ornamental plants for shady and low-light environments, but understanding the adaptations of plants that grow naturally in such conditions can lead to greater chances of success in horticulture. Shade-plants essentially follow strategies of optimum use of available energy and of conservation of energy. Adaptations to achieve these strategic goals include thinner leaves with a relatively higher chlorophyll content per unit leaf volume; lens-shaped epidermal cells that focus incoming light into and within the mesophyll; a red abaxial cell layer that reflects outgoing light back into the mesophyll; the greater allocation of available energy to defence-mechanisms against herbivory (as opposed to replacement of damaged tissue)—including camouflaging strategies such as mottled leaves; a distichous phyllotaxis; and flowers and fruit that are inconspicuous in size and colour. Many of the adaptations of shade-plants have a pronounced effect on their ornamental value, and can therefore also determine their differing possible horticultural uses. Knowledge of physiological adaptations and growth requirements is important in the successful cultivation and sustained utilization of ornamental shade-plants.