sieve tube

n. A tube through which food is conducted in angiosperms, formed of a series of sieve-tube elements joined end to end.

sieve tube

n (Botany) botany an element of phloem tissue consisting of a longitudinal row of thin-walled elongated cells with perforations in their connecting walls through which food materials pass

sieve′ tube`

n. Bot. a vertical series of cylindrical cells in the phloem, specialized for the conduction of food materials. [1870–75]

Thesaurus

Noun

sieve tube - tube formed by cells joined end-to-end through which nutrients flow in flowering plants and brown algaevascular tissue - tissue that conducts water and nutrients through the plant body in higher plantsphloem, bast - (botany) tissue that conducts synthesized food substances (e.g., from leaves) to parts where needed; consists primarily of sieve tubes

Sieve Tube

sieve tube

[′siv ‚tüb] (botany) A phloem element consisting of a series of thin-walled cells arranged end to end, in which some sieve areas are more specialized than others.

Sieve Tube

a conducting element of flowering plants. A sieve tube is a monostichous strand stretched the length of the cells; the end walls of the cells bear sieve plates containing sieve areas, which have numerous perforations lined with callose. Simple, usually horizontal plates have one sieve area (pumpkin, ash), whereas complex, slanted plates have several sieve areas (linden, grape, passionflower, rice). Each segment of the sieve tubes is adjoined by a strand of narrow companion cells. As the tubes develop, the tonoplasts in the cells are destroyed, the cytoplasm mixes with the cell fluid, and the organelles and nucleus deteriorate.

Most plants have sieve tubes that function for one year. However, the sieve tubes of grapes function for two years, those of lindens for several years, and those of some palms for decades. At the end of the vegetative period the sieve perforations are completely covered with callose, as are both sides of the sieve plates. The mass of callose on the sieve plates is called definitive callus. After the sieve tubes and their companion cells cease functioning, they disorganize and are obliterated.

L. I. LOTOVA

sieve tube

a series of long cells (sieve cells) lying end to end forming a tube, found in the PHLOEM of ANGIOSPERMS. Each sieve cell loses its nucleus when mature, but maintains the cytoplasm, which is continuous from one cell to another and crosses the cell boundaries via perforations in the wall called sieve plates. Associated with the sieve tube are modified PARENCHYMA cells each with a cytoplasm, nucleus and many MITOCHONDRIA, called companion cells. It is considered that the companion cells may regulate TRANSLOCATION of materials within sieve tubes since there are cytoplasmic connections between the sieve cells, and the companion cells and the sieve cells are anucleate.

sieve tube

sieve tube

sieve tube

sieve′ tube`

Sieve Tube

sieve tube

Sieve Tube

sieve tube

sieve tube

sieve tube

Words related to sieve tube

noun tube formed by cells joined end-to-end through which nutrients flow in flowering plants and brown algae

Related Words