The vascular system consists of two main complex tissue types: xylem and phloem. Xylem varies from a barely discernible trace in some herbaceous plants to the massive wood of trees. Phloem is much less conspicuous in most vascular plants. Vascular tissue extends from the roots to the leaves and is absent only in the very youngest of plant tissues. Functionally, XYLEM provides support from its reinforced cell walls, transport through continuous files of vessels and tracheids, and storage in parenchyma cells. Transport functions of PHLOEM are provided by sieve cells and sieve tubes, regulated it seems at least in angiosperms, by companion cells. Phloem fibres provide support and phloem parenchyma probably allows more cell space for storage.

Vascular Tissues:
XYLEM
PHLOEM
BACK TO CELL-TISSUE FRONTPAGE