Yours, Etc.: Origins and Uses of 8 Sign-Offs
1870, from German phloëm (1858), coined by German botanist Karl Wilhelm von Nägeli (1817-1891) from Greek phloos, phloios "bark of trees," of uncertain origin, + passive suffix -ema.
A tissue in vascular plants that conducts food from the leaves and other photosynthetic tissues to other plant parts. Phloem consists of several different kinds of cells: sieve elements, parenchyma cells, sclereids, and fibers. In mature woody plants it forms a sheathlike layer of tissue in the stem, just inside the bark. See more at cambium, photosynthesis. Compare xylem.