A bump in the node: the hydraulic implications of rhizomatous growth.

Nodal chokepoints decrease hydraulic integration between phytomers. At the same time, chokepoints may act as 'safety-valves', hydraulically localizing each phytomer-potentially decreasing embolism and pathogen spread-suggesting a potential tradeoff in the principal construction of the fern rhizome. Moreover, we propose that shoot-borne roots (homorhizy) and the prostrate habit of rhizomatous ferns decrease the hydraulic and structural burdens that upright plants typically incur. The absence of these hydraulic and structural demands may be one reason many rhizomatous plants lack, or have minimally developed, secondary xylem. This article is protected by copyright. All rights reserved.