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

VIII. FUNDAMENTALS OF PLANT MORPHOLOGY AND ANATOMY

Leaf Morphology and Anatomy

Leaf Metamorphoses

The most common among them are the following:

Tendrils are modifications of a leaflet (pea, vetch, tare) or the rachis (the central vein; milkvetch) in the form of slender, twining terminal leaf lobes. They enable plants with weak stems to cling to a support.

Trap devices are modified leaves found in carnivorous plants. In sundew, the leaf bears sticky digestive glands whose secretions, glistening in the sun, attract insects. The insects adhere to the leaves, where, with the aid of digestive juices, the plant absorbs nitrogenous compounds from them, which are essential for the plant's functioning.

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Fig. 76. Phyllotaxis and parts of a leaf:

1 - alternate phyllotaxis: пл - blade, ч - petiole; 2 - leaf with a sheath: п - sheath, я - ligule; 3 - leaves with stipules: пр - stipules; 4 - sessile stem-clasping leaf: в - auricle; 5 - opposite phyllotaxis; 6 - whorled phyllotaxis.

In the greater bladderwort (Utricularia vulgaris L.), leaf segments are modified into sac-like structures whose entrance is lined with hairs pointing inward. Daphnia and small crustaceans easily enter this trapping apparatus from which they cannot escape. Digestive glands located on its walls secrete Enzymes, allowing the plant to obtain nitrogenous compounds.

There are other leaf modifications in carnivorous plants that are widespread in the tropics and subtropics, though less common in our flora.

Phyllodes are a leaf modification typical of acacias, lemons, and other plants. In these, the leaf petiole or its segment develops into a leaf-like blade, thereby providing an additional photosynthetic surface for the plant.

In cacti, leaves are modified into spines to reduce plant Transpiration. Stipules (robinia) or lower leaves (barberry) may also be modified into spines.