An elongated, food-conducting cell in phloem in angiosperms. Unlike the tracheary elements of xylem, sieve elements have living protoplasts when mature, but they lack a nucleus and are dependent upon companion cells for certain functions. At the ends of each sieve-tube element are sieve plates, areas of the cell wall containing numerous large pores. The sieve-tube elements are aligned end to end and form continuous tubes, along which nutrients flow relatively unimpeded from cell to cell through the sieve plates. Sieve-tube elements are more specialized than the sieve cells found in gymnosperms. Compare sieve cell.
noun 1. an instrument with a meshed or perforated bottom, used for separating coarse from fine parts of loose matter, for straining liquids, etc., especially one with a circular frame and fine meshes or perforations. 2. a person who cannot keep a secret. verb (used with or without object), sieved, sieving. 3. to put or […]
adjective 1. (South African, slang) disgusting; sickening; nasty SIF somatotropin release-inhibiting factor
noun 1. either of two large rare arboreal lemuroid primates, Propithecus diadema or P. verreauxi, of Madagascar, having long strikingly patterned or coloured fur: family Indriidae