BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VIII. BASICS OF PLANT MORPHOLOGY AND ANATOMY

Morphology and Anatomy of the Leaf

As a vegetative organ of plants, the leaf evolved over the course of evolution. Its formation followed two pathways: either as an outgrowth of the outer Tissues of the stem, leading to The formation of small, awl-shaped false leaves (or phyllids) in mosses and clubmosses, or from modified telomes (branch systems) in horsetails, as well as fused and flattened telomes. Telomes were not yet differentiated into vegetative Organs, which ultimately resulted in the large leaves of ferns.

The leaf is regarded as a lateral plagiotropic organ with determinate growth specialized for Photosynthesis. In most plants, growth occurs at the base (intercalary), whereas in ferns it is apical.

In the vast majority of plants in the temperate zone, a leaf persists for only one growing season. In other plants, longevity varies: 2–3 years in pine, 3–5 years in yew, 4 years in laurel, 7–10 years in spruce, and over 100 years in welwitschia.

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Fig. 72. PARTS OF THE leaf: 1 - blade, 2 - petiole, 3 - stipules



Last update: 07/08/2026

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