Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- A small spike; the basic inflorescence unit in the Cyperaceae (sedges) and Poaceae (grasses). (inflorescence type)
Glossary of "The Evolution of Plants (2nd ed.)" by Willis & McElwain (2014)
- The basic unit of a grass inflorescence consisting of a short axis, two bracts, and one or more florets.
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.
- Willis, K. J. & McElwain, J. C. 2014. The Evolution of Plants, 2nd ed. -ix + 398 pp. Oxford University Press, Oxford.