BI111 Chapter Notes - Chapter 32.2: Urtica Dioica, Vacuole, Alkaloid
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Because plants cannot run away they seem ideal for food. Plants used mechanical and chemical defenses to avoid being eaten: A network of extracellular canals filled with white, sticky liquid called latex runs through the milkweed leaf both within the major veins and extending into the regions between veins. Latex canals are under pressure in the intact lead. When the vein is damaged latex flows out and is exposed to the air. Most plants have mechanical and chemical defenses against herbivores. Mechanical defenses include little hairs on plants. Chemical defenses include things like the stinging nettles reaction. Some plants produce alkaloids, a nitrogen based compound that damages the nervous system of animals. A second group of defense compound called terpenes do not contain nitrogen and plants can produce them for defense without having to make use of nitrogen that would otherwise be used in protein synthesis. Phenols illustrated by the tannins found widely in plant tissues.
