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The architecture of Castelnavia noveloi (Podostemaceae) – a re-investigation

Jäger-Zürn, Irmgard, Philbrick, C. Thomas, Bove, Claudia P.
Brittonia 2016 v.68 no.2 pp. 202-211
Neotropics, Podostemaceae, branching, hypocotyls, inflorescences, leaves, mature plants, photosynthesis, rivers, rocks, roots, seedling growth, shoots, stems
Podostemaceae occupy river rapids and waterfalls, where they attach to rocks in turbulent currents. All vegetative structures (roots, stems, leaves) are usually green and presumably photosynthetic, and highly variable in form among taxa. Here is reported the results of a study of a species of neotropical Castelnavia (C. noveloi). Published reports of the lack of roots in the species, as well as the presence of pinnately compound leaves, are challenged. Evidence based on early seedling growth indicates that prostrate roots develop exogenously from the hypocotyl base. After re-examining mature plants we interpret what was reported by earlier workers as pinnately compound leaves to be foliate roots. Examination of branching of mature shoots of C. noveloi indicate a form of sympodial branching system that is arranged in a dichasial order as helicoid, scorpoid, or fan-shaped cymes.