Lignin Leaf Skeleton
The minute patterns of veins on this magnolia leaf are drawn by lignin-rich tissue. Lignin is a compound found in all woody plants that hardens, preserves, and protects the cellulose-rich tissue. Lignin is a complex molecule that is impossible to digest by most organisms. A few fungi and other species digest lignin, while many more digest cellulose, which makes up the bulk of the leaf. While most of the cellulose in this leaf has been digested after one or two seasons on the ground, it is the lignin that remains.
The network-like veins of this plant indicate that it is a dicot, and this kind of venation (reticulate) is homologous in most dicots, an inherited feature that indicates their descent from a common ancestor.
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