Vascular Tissue: Phloem
located towards outer part of roots and stem (severe injury of tree bark can lead to death by starvation of tree)
Aggregations of two cell types (both living, but may lack nucleus): sieve cells and sieve-tube members (difference = size of pores)
Sieve area = cluster of pores at cell ends, forming sieve plate
Companion cell: parenchyma cells that maintain metabolic function of sieve cells, connected through plasmodesamata