Journal Article

The evolution of root hairs and rhizoids

Victor A.S. Jones and Liam Dolan

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 110, issue 2, pages 205-212
Published in print July 2012 | ISSN: 0305-7364
Published online June 2012 | e-ISSN: 1095-8290 | DOI:
The evolution of root hairs and rhizoids

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry


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Almost all land plants develop tip-growing filamentous cells at the interface between the plant and substrate (the soil). Root hairs form on the surface of roots of sporophytes (the multicellular diploid phase of the life cycle) in vascular plants. Rhizoids develop on the free-living gametophytes of vascular and non-vascular plants and on both gametophytes and sporophytes of the extinct rhyniophytes. Extant lycophytes (clubmosses and quillworts) and monilophytes (ferns and horsetails) develop both free-living gametophytes and free-living sporophytes. These gametophytes and sporophytes grow in close contact with the soil and develop rhizoids and root hairs, respectively.


Here we review the development and function of rhizoids and root hairs in extant groups of land plants. Root hairs are important for the uptake of nutrients with limited mobility in the soil such as phosphate. Rhizoids have a variety of functions including water transport and adhesion to surfaces in some mosses and liverworts.


A similar gene regulatory network controls the development of rhizoids in moss gametophytes and root hairs on the roots of vascular plant sporophytes. It is likely that this gene regulatory network first operated in the gametophyte of the earliest land plants. We propose that later it functioned in sporophytes as the diploid phase evolved a free-living habit and developed an interface with the soil. This transference of gene function from gametophyte to sporophyte could provide a mechanism that, at least in part, explains the increase in morphological diversity of sporophytes that occurred during the radiation of land plants in the Devonian Period.

Keywords: Rhizoids; root hairs; Physcomitrella patens; Arabidopsis thaliana; root; root systems; nutrient uptake; soil; tip growth; life cycle; alternation of generations; streptophyte

Journal Article.  6245 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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