Glossary of "Plant Biology (1st ed.)" by Graham et al. (2003)
- A type of specialized cell that is produced by the same division that gives rise to a sieve tube member in angiosperm phloem; provides materials to sieve tube elements.
Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- A parenchyma cell associated with a sieve tube member, derived from the same parent cell as is the sieve tube member and functioning to load and unload sugars into the cavity of the sieve tube member.
- Graham, L. E., Graham, J. M. & Wilcox, L. W. 2003. Plant Biology. -xxxv + 497 pp. Pearson Education, Inc., Upper Saddle River.