The epidermis consists of the upper and lower epidermis; it aids in the regulation of gas exchange via stomata. Plant Anatomy Label Me! Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Leaf Structure and Function For a typical leaf, we use that of the umbrella tree, which is commonly sold as a foliage plant throughout North America and Europe. In cacti, spines are wholly transformed leaves that protect the plant from herbivores, radiate heat from the stem during the day, and collect and drip condensed water vapour during the cooler night. They are attached by a continuous vascular system to the rest of the plant so that free exchange of nutrients, water, and end products of photosynthesis (oxygen and carbohydrates in particular) can be carried to its various parts. Role of leaves: Trap light for photosynthesis Exchange gases 3. The epidermis aids in the regulation of gas exchange. Missed the LibreFest? Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. The main function of a leaf is to produce food for the plant by photosynthesis. New Phytol 134:35–51 CrossRef Google Scholar. It consists of the upper and lower epidermis, which are present on either side of the leaf. In the water hyacinth (Eichhornia crassipes), swollen petioles keep the plant afloat. A waxy layer known as the cuticle covers the leaves of all plant species. The cells of the leaf buttress may…. These needle-like leaves have sunken stomata and a smaller surface area, two attributes that aid in reducing water loss. The internal structure of the leaf is protected by the leaf epidermis, which is continuous with the stem epidermis. It consists of the upper and lower epidermis, which are present on either side of the leaf. Benz BW, Martin CE (2006) Foliar trichomes, boundary layers, and gas exchange in 12 species of epiphytic Tillandsia (Bromeliaceae). Watch the recordings here on Youtube! Yellow and orange pigments called carotenoids become more conspicuous, and, in some species, anthocyanin pigments accumulate. Pigments other than chlorophyll give this maple leaf its autumn colours. Trichomes help to avert herbivory by restricting insect movements or by storing toxic or bad-tasting compounds. In most plants, leaves are the major site of food production for the plant. Leaves of dicots possess a network of interconnecting veins…, Leaves originate on the flanks of the shoot apex. The fall of leaves, whether in the first autumn in most deciduous trees or after several years in evergreens, results from the formation of a weak zone, the abscission layer, at the base of the petiole. The outermost layer of the leaf is the epidermis. Chlorophyll production in deciduous plants slows as the days get shorter and cooler, and eventually the pigment is broken down completely. The structure of a ... A cross-section through a leaf Features of leaves and their functions. Plants in cold climates have needle-like leaves that are reduced in size; plants in hot climates have succulent leaves that help to conserve water. External structure of a leaf margin petiole [leaf stalk] midrib vein lamina [blade] 5. Leaf structure. In hot climates, plants such as cacti have succulent leaves that help to conserve water. In perennial plants, leaf fall is usually associated with approaching winter dormancy. Structures within a leaf convert the energy in sunlight into chemical energy that the plant can use as food. Crenulate margins have rounded teeth or scalloped margins. Glands in the leaves secrete enzymes that digest the captured insects, and the leaves then absorb the nitrogenous compounds (amino acids) and other products of digestion. Home > GCSE Biology > Photosynthesis. In nasturtium (Tropaeolum majus) and Clematis, the petioles coil around other plants for support. In angiosperms leaves commonly have a pair of structures known as stipules, which are located on each side of the leaf base and may resemble scales, spines, glands, or leaflike structures.