Inverted vascular bundles in the leaf of Cladium (Cyperaceae)

Illustrations of seedling development and the adult plant of Cladium jamaicense Crantz are given. The course of vascular bundles in the leaf is described in detail. The structure of seedling and adult leaves are compared. Development of leaf primordia and initiation of vascular bundles are followed. Changes in the anatomy within one leaf and differences between foliage leaves and scales are related to their development. The adaxial vascular bundles that are inversely orientated are initiated within a procambial complex in close association with the largest abaxial bundles. Normally orientated adaxial bundles have an origin independent of other bundles. A hypothesis is presented which accounts for the differentiation of inverted bundles in morphogenetic terms. No developmental evidence was found to support the phylogenetic derivation of the leaf of Cladium by adaxial folding and fusion of laminar halves with their own adaxial surfaces.