vascular bundle defined in 1951 yearvascular bundle - vascular bundle;
vascular bundle - Longitudinal strand of conducting (vascular) tissue consisting essentially of xylem and phloem; unit of stelar structure in stems of gymnosperms and angiosperms and occurring in appendages of stem, e.g. veins in leaves. In stems of gymnosperms and dicotyledons, arranged in a ring surrounding the pith, in monocotyledons, scattered throughout tissue of stem. May be (a) collateral, with phloem on same radius as xylem and external to it; typical condition in angiosperms and gymnosperms. (b) Bicollateral, with two phloem groups, external and internal to xylem, on same radius; uncommon, occurring in some dicotyledons, e.g. marrow. (c) Concentric, with one tissue surrounding the other. Concentric bundles are amphkribral when phloem surrounds xylem, e.g. in some ferns, and amphivasal when xylem surrounds phloem, e.g. in rhizomes of certain monocotyledons. Vascular bundles are further described as open, when cambium is present, e.g. in most dicotyledons, and closed, when cambium is absent, e.g. in monocotyledons.
near vascular bundle in Knolik
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