Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- The opening between two guard cells of a stomate.
Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- Small opening in the plant epidermis that permits gas exchange; bounded by a pair of guard cells whose osmotic status regulates the size of the opening.
Glossary of "The Evolution of Plants (2nd ed.)" by Willis & McElwain (2014)
- Pores in the epidermis of above-ground parts of plants, which enable gaseous exchange between the internal tissues and the atmosphere.
- Sadava, D., Hillis, D. M., Heller, H. C. & Berenbaum, M. R. 2011. Life: The Science of Biology, 9th ed. -xliv + 1266 pp. Sinauer Associates, Inc., Sunderland.
- Willis, K. J. & McElwain, J. C. 2014. The Evolution of Plants, 2nd ed. -ix + 398 pp. Oxford University Press, Oxford.