13.3 Plant Organs and functions - Stems leaves

13.3 Plant Organs and their functions STEMS Stems Functions: provide support for the plant transport link to and from leaves, roots and reproductive parts store water and carbohydrates Structures: stems increase in length when the apical meristem at the tips of the shoots divides herbaceous stems- green, fleshy, perform photosynthesis woody stems- stiff, not green, survive long time; grow in diameter as well as length Structure: see Figure 3 p. 520 the meristematic region is at the tip of each shoot there is an area below it where the cells grow (elongation) primary tissues develop into xylem phloem etc Vascular bundles- made of xylem and phloem are distributed differently in monocot and dicot stems monocot are scattered, dicot in rings (so that secondary growth can occur) ground tissue – sometimes called pith -stores and supports cambium- meristematic tissue that produces secondary xylem and phloem (and growth rings) Secondary growth- in woody dicots bark- made of everything from the vascular cambium outward; if bark is removed, the phloem is destroyed and the tree will die heartwood- non-living central wood – made of old xylem sapwood- living xylem 13.3 Plant Organs and their functions LEAVES Leaves are organs and are the site of photosynthesis. What are the raw materials for photosynthesis? How do these raw materials get to the leaf? What are the products of photosynthesis? How do these products get out of the leaf? Photosynthesis requires: 1. Light 2. CO2 3. Water, minerals How leaf gets: 1. Chlorophyll captures light (makes leaf green) Leaf has a large surface area. 2. Guard cells in leaf allow gases to enter. 3. Veins are extensions of the stem’s vascular system The working layers of a leaf {5C22544A-7EE6-4342-B048-85BDC9FD1C3A}Part Function Structure Tissue cuticle upper epidermis palisade mesophyll spongy mesophyll lower epidermis vein {5C22544A-7EE6-4342-B048-85BDC9FD1C3A}Part Function Structure Tissue cuticle prevents water loss by transpiration wax none upper epidermis protects Makes waxy cuticle dermal palisade mesophyll perform photosynthesis chloroplast ground spongy mesophyll perform photosynthesis Chloroplast; air spaces to maximize CO2 gain ground lower epidermis Protects, allows gas exchange contains “guard cells” to allow air to enter leaf and water to leave dermal vein transport contain xylem and phloem vascular stoma are open if the plant is doing photosynthesis (if humidity inside leaf is high enough and there is light) How can plant leaves adapt to extreme wet? Dry? Cold? Hot? Xerophyte Hydrophyte Mesophyte Root, Stem, Leaf Rap!!! In groups of 2-3, write a rap that talks about the various organs of plants! Be sure to include structures and functions of all these organs. Hand in your rap once it is complete. Homework: P 559 # 5-7, 9-16