Anatomy and histochemistry of Triarrhena lutarioriparia var. humilior from the Jianghan Floodplain, China

Abstract

This study examined the perennial Triarrhena lutarioriparia var. humilior to identify the anatomical and histochemical features that support the adaptation of this plant to the seasonal flooding of the Jianghan Floodplain, China. The leaves, culms, rhizomes, and adventitious roots of T. lutarioriparia var. humilior were collected in the Jianghan Floodplain. T. lutarioriparia var. humilior is a typical C4 species with Kranz anatomy: chloroplasts were present in the parenchymatous and/or mestome sheaths. The apoplastic barriers of T. lutarioriparia var. humilior consisted of an endodermis and exodermis, as well as a suberized vascular system, peripheral sclerenchyma ring, and epidermis. These structures may prevent oxygen loss and facilitate nutrient transport under submerged conditions. The mechanical tissues of T. lutarioriparia var. humilior included a peripheral mechanical ring, sclerenchyma ring, vascular bundles, and sclerified bundles, as well as a peripheral ring adjacent to the vascular bundles in the culms. T. lutarioriparia var. humilior also had air spaces in the roots and stems. These combinations of traits show that T. lutarioriparia var. humilior, like other species in the same localities, is well adapted to the seasonal flooding of its habitat.