Root structure of Rumex scutatus growing on slopes

Abstract

The effect of slope on root architecture and anatomy of Rumex scutatus L. was analysed in plants growing on slopes and on flat ground, on the flanks of Mt. Vesuvius. Roots of plants on steep slopes developed asymmetrically, with lateral roots growing upslope acting as tie-rods. In roots growing on flat ground, lignified xylem was limited to thin radial strips, surrounded by unlignified parenchyma cells filled with starch. A trend towards a larger lignified area was evident from plants growing on flat ground to those on steep slopes, as well as from taproots to tie-rod roots. The latter also showed larger vessels and a lower incidence of narrow vessels than taproots. Roots developing on steep slopes were characterised by high frequency of very-thick-walled, lignified fibres with long tips which accumulated both starch and phenolic compounds. Such fibres did not show lignified cell walls in roots growing on flat ground. Overall analysis showed that slope influences root architecture and anatomical traits, not only affecting mechanical properties but also water transport capacity.