Companion cells are usually seen associated with which tube?
Companion cells and sieve elements are of meristematic origin, their development is similar to that of the xylem. Primary phloem develops by longitudinal division and subsequent elongation of meristematic cells. The cells do often divide unequally. The bigger daughter cell differentiates into a sieve element, the smaller after one or two further longitudinal divisions into two to four companion cells. Consequently several companion cells may belong to one sieve cell.
