Figure 1 First occurrences of some morphological and anatomical features in the fossil record of Upper Silurian and Devonian Period vascular land plants (Niklas, 1992): (a) equal branching, (b) tracheids, (c) stomata, (d) unequal branching, (e) vascularized appendages, (f) adventitious roots, (g) planated lateral branches, (h) continuous periderm, (h') patches of periderm, (i) dissected steles, (j) secondary xylem, (k) planated, webbed leaves, (l) ovules.

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