Anatomy of stem-node-leaf continuum in Aconitum L. (Ranunculaceae) in the Eastern Carpathians
19 May 2015
Novikoff, Andrew; Mitka, JózefResearch on the anatomical structure of the stem and leaf with special emphasis on the organization of the vascular system was carried out on 13 Aconitum species from the subg. Aconitum, Anthora and Lycoctonum. All investigated species show a more or less mesomorphic anatomical structure, typical for other Ranunculaceae. Hence, these species have similar trilacunar three-trace organization of the nodal vascular system. In the stem, open (with weakly developed cambium) or closed collateral, and incomplete (constituting of phloem only) vascular bundles were observed. While in the petiole, three groups of the bundles were represented: large complete, middle-size complete and small incomplete or with weakly developed xylem. The number of vascular bundles in petioles has no strict taxonomical value. Nevertheless, it was ascertained that spatial organization of these vascular bundles in the petiole has a strict taxonomic value. As a result, the investigated species can be divided into four main groups corresponding to the sectional and subgeneric division of the Aconitum genus. The only exception was A. ×cammarum (sect. Acomarum) which is identical to the sect. Cammarum organization of the petiolar vasculature. The most primitive vascularization is considered for A. anthora, while the most advanced one found in A. variegatum. The distinct nodal anatomy features of A. anthora suggests its high, seemingly a subgeneric, taxonomical rank.