Structure–function constraints of tracheid-based xylem: a comparison of conifers and ferns
Article first published online: 12 JUL 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 192, Issue 2, pages 449–461, October 2011
How to Cite
Pittermann, J., Limm, E., Rico, C. and Christman, M. A. (2011), Structure–function constraints of tracheid-based xylem: a comparison of conifers and ferns. New Phytologist, 192: 449–461. doi: 10.1111/j.1469-8137.2011.03817.x
- Issue published online: 27 SEP 2011
- Article first published online: 12 JUL 2011
- Received: 20 April 2011, Accepted: 6 June 2011
- gas exchange;
- hydraulic conductivity;
- primary xylem;
- xylem evolution
- •The ferns comprise one of the most ancient tracheophytic plant lineages, and occupy habitats ranging from tundra to deserts and the equatorial tropics. Like their nearest relatives the conifers, modern ferns possess tracheid-based xylem but the structure–function relationships of fern xylem are poorly understood.
- •Here, we sampled the fronds (megaphylls) of 16 species across the fern phylogeny, and examined the relationships among hydraulic transport, drought-induced cavitation resistance, the xylem anatomy of the stipe, and the gas-exchange response of the pinnae. For comparison, the results are presented alongside a similar suite of conifer data.
- •Fern xylem is as resistant to cavitation as conifer xylem, but exhibits none of the hydraulic or structural trade-offs associated with resistance to cavitation. On a conduit diameter basis, fern xylem can exhibit greater hydraulic efficiency than conifer and angiosperm xylem.
- •In ferns, wide and long tracheids compensate in part for the lack of secondary xylem and allow ferns to exhibit transport rates on a par with those of conifers. We suspect that it is the arrangement of the primary xylem, in addition to the intrinsic traits of the conduits themselves, that may help explain the broad range of cavitation resistance in ferns.