Bagniewska-Zadworna A., Byczyk J., Eissenstat D. M., Oleksyn J., Zadworny M. 2012. Avoiding transport bottlenecks in an expanding root system: Xylem vessel development in fibrous and pioneer roots under field conditions. American Journal of Botany. 99(9): 1417-26. doi:10.3732/ajb.1100552