Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- A generally dorsi-ventrally flattened organ, usually functioning in photosynthesis and transpiration, either gametophytic (in mosses and some liverworts) or sporophytic (in vascular plants), often variously modified. (plant part)
Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- 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.
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.