Sieve plate

Unlike xylem, phloem contains living cells. Its sieve-tube cells join end-to-end, but their end walls remain. These end walls contain pores and are called sieve plates: dissolved substances can pass through the pores from one cell to the next.

Phloem contains living sieve-tube cells joined end-to-end. Their end walls contain holes and are called sieve plates. These holes allow dissolved sucrose to flow between cells.