Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- A large, internal, membrane-bound sac of plant cells that functions in storage of compounds such as pigments, acids, or ergastic substances.
Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- Membrane-enclosed organelle in plant cells that can function for storage, water concentration for turgor, or hydrolysis of stored macromolecules.
Glossary of "Evolution of Plants (2nd ed.)" by Willis & McElwain (2014)
- A fluid-filled cavity within the cytoplasm of plant cells.
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.
- 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.