![]() ![]() The edges of all leaves are called margins and can be smooth or toothed but can also be entire (without lobes) or with a lobe and a sinus.Ī Tree leaf can be symmetric or asymmetric off the midrib or midvein. True leaves are blade-like and have a connection to the twig called a stalk or petiole. Even slight differences can determine an exact tree species identification. Most trees can be identified by the leaf alone - they are unique! Tree Leaves come in many shapes and sizes, many with similar structures but most with subtle differences. Steve Nix Botanical Structures on a LeafĪ tree's leaf is the best major botanical marker that helps in keying out and identifying any species of tree that has a leaf. Guard cells – Specialized kidney-shaped cells that open and close the stomata. Stomata – Natural openings in leaves and herbaceous stems that allow for gas exchange (water vapor, carbon dioxide and oxygen). Spongy mesophyll – Layer of parenchyma tissues loosely arranged to facilitate movement of oxygen, carbon dioxide, and water vapor. Vascular bundle – Xylem and phloem tissues, commonly known as leaf veins. Chloroplasts contain chlorophyll, a green plant pigment that captures the energy in light and begins the transformation of that energy into sugars. Palisade layer – A tightly packed layer of long tube-like parenchyma tissues filled with chloroplasts for photosynthesis.Ĭhloroplasts – Sub-cellular, photosynthetic structures in leaves and other green tissues. Leaf hairs – Coverings on a leaf's epidermis that may or may not exist with every tree species. Find these structures on the attached diagram of cellular leaf tissues.Įpidermis – The leaf's outer layer and protective "skin" surrounding leaf tissues.Ĭuticle – A waxy protective coating on the leaf epidermis that prevents water loss on leaves, green stems, and fruits. The leaf blade is composed of tissue layers, each having an important part to play in a functioning leaf. With the exchange of water and the absorption of carbon dioxide during the process of photosynthesis, the release of life-sustaining oxygen occurs as a by-product. ![]() Through small openings on the leaf, called stomata, a tree can regulate moisture and gasses. Both of these processes support evapotranspiration which allows the tree to move water and nutrients up from the roots. Powered by sunlight, the green substance in leaves called chlorophyll, use carbon dioxide and water to produce life-sustaining carbohydrates (sugars). The entire process is called photosynthesis.Ī tree's leaves are also responsible for the twin functions of respiration and transpiration. ![]()
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