Origin of inverted vascular bundles in winged leaves of Scleria plusiophylla (Cyperaceae)

Abstract

The genus Scleria P.J. Bergius is pantropical, occurs in various habitats such as forests, fields, and wetlands, and is morphologically diverse. Some species have a winged sheath, which remains on the leaf blade and forms the last pair of costae. Anatomical observations of leaf blades of Scleria plusiophylla Steud. revealed the presence of inverted vascular bundles in the region of the wing. During the development of the shoot apical meristem of S. plusiophylla, it was observed that the wing emerges through divisions and enlargement of protoderm cells of the abaxial surface and subsurface cells (ground meristem) of the sheath. The ground meristem, from both sides of the sheath, gives rise to the procambial strands, which have normal differentiation. Subsequently, in the transition region between the sheath and the leaf blade, the growth of the sheath ends and the development of the leaf blade continues with the wings remaining adnate to the blade and initially folded towards the dorsal surface. As the leaf blade develops, the wings gradually unfold. Bulliform cells on the abaxial surface of the epidermis, which marked the beginning of the wing, and inverted vascular bundles intercalated with normal vascular bundles, are also observed. It was concluded that all of the bundles in the wing of the leaf blade have normal development and follow the orientation of development related to the side of the sheath from which they were initially derived, resulting in vascular bundles with different phloem positions.