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

摘要

Absorbing roots and anchoring roots ofAsplundiasp.,Evodianthus fiinifer, andThoracocarpus bissectusdiffer from one another anatomically in at least 15 quantitative characteristics and in additional related respects. Differences are diverse, involving both stelar and extrastelar tissues. Absorbing roots are significantly greater in diameter, have more vascular tissue, exhibit broader tracheary elements and sieve elements, and have other characteristics supporting the hypothesis that those features logically interpretable as optimizing conduction in xylem and phloem predominate in the absorbing roots. The three species also differ significantly from each other according to the anatomy of their absorbing roots, withT.bissectushaving the most distinctive anatomy. Statistical and nonstatistical approaches to analysis of the data provided very consistent results, both in regard to differences between the two root types under study and to differences between taxa.Key words: absorbing roots, anchoring roots,Asplundia, Cyclanthaceae,Evodianthus, root anatomy,Thoracocarpus.