SIEVE TUBES

Several sieve cells contribute to the formation of sieve tube. The sieve tube contains living cytoplasm. The sieve tube is devoid of nucleus. The transverse separating walls of the longitudinally arranged sieve cells become perforated. These pores are called sieve plates. The cytoplasmic strands are seen passing through the sieve pores in the sieve plates. These strands are said to be the pathways or channels for food conduction.