Faculty Publications

Specializations in Leaf Structure and Function

Document Type

Book Chapter

Journal/Book/Conference Title

Kaplan's Principles of Plant Morphology


Thorn leaves are appendages where a part or all of their tissues undergo sclerification, or hardening, by the differentiation of tough, thick-walled, lignified tissues in their mesophyll. Sclerification of leaf apices also occurs in the angiosperms, but it can be extended to the entire surface of the upper leaf zone. Leaf tendrils are found exclusively in angiosperms, particularly dicotyledons. However, there are monocotyledons, such as species in the genera Smilax, Flagellaria, and Gloriosa which also have leaf tendrils. The transformation of leaflets into tendrils obviously involves a reduction in blade surface in favor of elongation growth as the twining organ. Like Clematis, various species in the family show transitions between conventional pinnate leaves, those with thigmotropic petioles, and pinnae which are modified as tendril filaments. The leaf of Adlumia fungosa serves morphologically as a bridge between the leaf type described in Fumaria and the more typical tendril leaves in other members of the family.


Department of Biology

Original Publication Date


DOI of published version