Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- Cells that, at maturity, are alive and potentially capable of cell division, are isodiametric to elongate in shape, and have a primary cell wall only (rarely with secondary wall), forming a solid mass of tissue and functioning in metabolic activities and in wound healing and regeneration.
Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- A plant tissue composed of relatively unspecialized cells without secondary walls.
- 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.