Glossary of "Evolution of Plants (2nd ed.)" by Willis & McElwain (2014)
- A unit of classification of vegetation defined on the basis of distinctive physiognomy rather than distinctive species composition. Formations are broadly equivalent with biomes.
- Willis, K. J. & McElwain, J. C. 2014. The Evolution of Plants, 2nd ed. -ix + 398 pp. Oxford University Press, Oxford.