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leaf trace[′lēf ‚trās]
a vascular bundle in the stem of a plant that directly connects the stem with a leaf. Depending on the plant species, one or several leaf traces may be associated with each leaf. From the base of the leaf down through the stem, the leaf trace passes through several internodes that correspond to the particular leaf arrangement and encounters and merges with other leaf traces that lead to previously developed leaves. Thus, a unified network of conducting bundles is formed in the shoot. Some vascular plants, such as lycopods, have small simple leaves (microphylls) with weak leaf traces that do not reach the conducting cylinder of the stem. The macrophyllous leaves of the Polypodiaceae, Gymnospermae, and Angiospermae have large leaf traces and are characterized by numerous leaf gaps.