ANATOMICAL ADAPTATIONS IN THE LEAVES OF SELECTED FYNBOS SPECIES

Fynbos plants experience very harsh conditions during the hot and dry summer months and their leaves are adapted to reduce the loss of water due to transpiration. The leaves of 46 selected fynbos species of 24 families were examined to determine which anatomical adaptations contr ibute to the reduced rate of transpiration and subsequent reduced wate r loss. Without exception, all species examined show leaf adaptations typical of xerophytic species. Four typical leaf types are recognized and proposed as models of leaf adaptation: 1. Myrsine type - dorsivent ral or isobilateral leaves; more palisade parenchyma present than spon gy parenchyma; tissues contain large amounts of phenolic substances. 2 . Metalasia type - small dorsiventral leaves with involute margins and a single groove in the adaxial surface; mesophyll is usually inverted . 3. Retzia type - dorsiventral or isobilateral leaves with revolute m argins and one or two grooves in the abaxial surface: spongy parenchym a is the main component of the mesophyll. 4. Spatalla type - small cen tric or near-centric leaves: little or no spongy parenchyma tissue.