BOTANY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site sieve-tube A characteristic element of phloem, which functions in the transport of food materials, such as sugars and proteins, synthesized within a plant. A sieve-tube consists of elongated, thin-walled, living cells arranged in a longitudinal row and forming a connected series by means of perforations in their walls through which pass strands of cytoplasm. These perforations occur in groups known as sieve-plates in the end or lateral walls. Sieve-tubes are remarkable in that their cells lack nuclei when mature. They are closely associated with parenchymatous companion cells with prominent nuclei. Related category    • BOTANY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP