Plasticity in anatomical traits of Cyperus niveus Retz. along elevational gradient of dry sub-Himalayan mountains

Abstract

Cyperus niveus Retz., also known as snow white sedge grows in dry mountainous regions of Himalayas. Eight populations of C. niveus were collected from different locations in the Salt Range (Punjab) and Kaghan Valley (Khyber Pakhtoonkhwa) to evaluate role of plasticity in adaptability potential through modification in anatomical traits. This species developed xeric anatomical modifications in roots at higher elevations. These were thick endodermis, formation of sclerenchymatous cells outside endodermis, numerous metaxylem vessels, and increased area of central vessel in roots. Roots were more developed in the Kaghan (K) population, showing the largest root radius (774.7 µm), sclerenchymatous cell area (1429.1 µm2), cortical thickness (147.1 µm), and endodermal cell area (7701.4 µm). Stomatal density (21.7 per mm2) was also the highest in the K population. Formation of aerenchymatous cavities, numerous large vascular bundles with wide metaxylem vessels, and large phloem tissue in stems were the prominent features in the K population at the highest elevation (2078 m a.s.l.). All C. niveus populations showed sclerification around and outside of the vascular bundles, larger adaxial epidermal cell area as compared to abaxial epidermal cells, hypostomatal leaves, and increased storage parenchyma in leaves.