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PARTS OF A FLOWER Peduncle: The stalk of a flower. Receptacle: The part of a flower stalk where the parts of the flower are attached. Sepal: The outer parts of the flower (often green and leaf-like) that enclose a developing bud. Petal: The parts of a flower that are often conspicuously colored. Stamen: The pollen producing part of a flower, usually with a slender filament supporting the anther. (male reproductive system) Anther: The part of the stamen where pollen is produced. Pistil: The ovule producing part of a flower. The ovary often supports a long style, topped by a stigma. The mature ovary is a fruit, and the mature ovule is a seed. (Female reproductive system) Stigma: The part of the pistil where pollen germinates. Ovary: The enlarged basal portion of the pistil where ovules(eggs) are produced. XYLEM AND PHLOEM TUBES Xylem & Phloem vessels Get Things Moving Read the passage below and answer the following questions. Most plants are vascular plants, having organized systems for transporting materials around to the various parts of the plant. We all know that the human body has organs in it, like the heart, lungs, kidneys and so on. But vascular plants have organs, too. The organs in a vascular plant include leaves, roots and stems. Leaves help the plant produce food by gathering sunlight and using it in the process of photosynthesis. The roots help the plant stay in one place. They burrow down into the ground and hold on. The roots also absorb nutrients and water out of the ground that the plant can use. Stems hold water, and help support the plant. They also act as a highway system to help plants get what they need. There are two kinds of vascular tissue inside the plant’s organs: xylem and phloem. Xylem carries water and nutrients through the plant from the roots to the stem and leaves. Xylem always flows up, not down. After sugar is made in the leaves during the process of photosynthesis, phloem picks up the sugar and carries it throughout the plant. The natural direction of phloem is downward, but it can flow upward when it has sugar to deliver. Sometimes the plant needs to use the sugar right away. At other times, the sugar is stored to be used later. Vascular tissue is found in clusters in most plants, with xylem and phloem “packaged” together. It takes a certain amount of “pull” to make water flow up a plant. Root pressure gets the process started. Roots tend to be salty, which draws water in. The special tissue of the roots prevents the water from going back out. Water drops cling to each other, and to some other molecules. This property of water is called cohesion. But even root pressure and cohesion are not enough. Transpiration is the final piece that keeps things moving. As water evaporates off of the plant’s leaves, it “pulls” more water up through the plant to take its place. In fact, almost all of the water that flows through a plant moves up through the plant fairly quickly and is transpired. 1) What is a vascular system? 2) What is the main difference between xylem and phloem vessels? 3) What are the three primary organs in a vascular plant? 4) Why is it important to the plant that phloem moves both up and down? 5) How does water flow up a plant? ANATOMY OF A LEAF Leaves are the powerhouse of plants. In most plants, leaves are the major site of food production for the plant. Structures within a leaf(chloroplasts) convert the energy in sunlight into chemical energy that the plant can use as food. Chlorophyll is the molecule in leaves that uses the energy in sunlight to turn water (H2O) and carbon dioxide gas (CO2) into sugar and oxygen gas (O2). This process is called photosynthesis. Leaf structure A leaf is made of many layers that are sandwiched between two layers of tough skin cells (called the epidermis). The epidermis also secretes a waxy substance called the cuticle. These layers protect the leaf from insects, bacteria, and other pests. Among the epidermal cells are pairs of sausage-shaped guard cells. Each pair of guard cells forms a pore (called stoma; the plural is stomata). Gases (Carbon dioxide and oxygen) enter and exit the leaf through the stomata. Veins support the leaf and are filled with vessels(xylem and phloem) that transport food, water, and minerals to the plant. cuticle - the waxy, water-repelling layer on the outer surface of a leaf that helps keep it from dying out (and protect it from invading bacteria, insects, and fungi). The cuticle is secreted by the epidermis (including the guard cells) and is often thinner on the underside of leaves. The cuticle is generally thicker on plants that live in dry environments. palisade mesophyll - a layer of elongated cells located under the upper epidermis. These cells contain most of the leaf's chlorophyll, converting sunlight into usable chemical energy for the plant. spongy mesophyll - the layer below the palisade mesophyll; it has irregularly-shaped cells with many air spaces between the cells. These cells contain some chlorophyll. The spongy mesophyll cells communicate with the guard cells (stomata), causing them to open or close, depending on the concentration of gases. COLOR AND LABEL THE ANATOMY OF A LEAF