Comparative morphology and anatomy of absorbing roots and anchoring roots in three species of Cyclanthaceae (Monocotyledoneae)

Abstract

Asplundia sp., Evodianthus funifer, and Thoracocarpus bissectus are root-climbing lianas that each have absorbing roots and anchoring roots. On stems appressed to the trunks of host trees, both types of roots arise mainly from internodes, generally emerging from those halves of stem surfaces facing the trunks (Asplundia sp., E. funifer), and may form nonreplacement roots and replacement roots. Aerial portions of absorbing roots differ from anchoring roots according to direction of growth, abundance of nonreplacement roots, diameter 1 cm distal to base, length, abundance, and color (T. bissectus). In all species the anchoring roots (with or without replacement roots) are interpretable as determinate because on long specimens their distal portions appear anatomically narrowed and reduced. In contrast, aerial parts of absorbing roots are indeterminate. The determinate aspects of anchoring roots and the general restriction (on stems appressed to tree trunks) of roots to trunk-facing stem surfaces are advantageous as means for conserving biomass. Key words: roots, root morphology, root dimorphism, Cyclanthaceae.