Unit 5 Plants

 Economic value: wood products/lumber  Connect the vascular tissue in the leaves to the vascular tissue in the roots, allowing water and dissolved substances to be transported throughout the body

 Raise and support the leaves (maximizing photosynthesis) and reproductive organs (maximizing the likelihood of being pollinated and producing fruits and seeds)

 Herbaceous Plants:  plants that have stems that do not contain wood  Relatively pliable stems  Stems carry out photosynthesis  Thin epidermis

 Vascular tissue in herbaceous plant stems are arranged in vascular bundles  Vascular bundles contain xylem and phloem  Xylem is always closer to the centre of the stem  Phloem is always closer to the outside of the stem  In monocots: ▪ Vascular bundles found through out the ground tissue  In dicots: ▪ Vascular bundles form a ring

 Woody plants:  Stems that contain wood  Woody stems are relatively hard  Have bark  Usually do not carry out photosynthesis

 Wood stems grow thicker every year due to the presence of the vascular cambium  Vascular Cambium: the meristematic cell layer in the vascular tissue that divides to form new xylem and phloem tissue  Xylem is on the inside of the vascular cambium  Phloem is on the outside

 Wood is many layers of xylem tissue cells  Sapwood is the younger xylem through which water and minerals are transported to the leaves  Eventually, the older xylem fills up with resin and oils and they no longer conduct water forming the heartwood which is very rigid and helps support the tree

 AQeQ AQeQ

 Bark consists of all tissues found outside the vascular cambium  Phloem ▪ transports sugars made in the leaves throughout the plant.  Cork cambium ▪ meristematic tissue that produces cork  Cork ▪ the tough, outer layer of the tree that prevents water loss from the stem

 Growth only happens in the spring and summer  In spring, vascular cambium grows rapidly, producing large xylem cells that have relatively thin walls that form a layer of lighter-coloured wood  In summer, fewer xylem cells are produced and they have thicker cells walls that form a layer of darker-coloured wood  The spring and summer wood together forms one growth ring

 Function of Roots:  Anchors the plant  Keeps it upright  Absorbs waters and nutrients (0ther than carbohydrates)  Store water and carbohydrates

 Taproot: a root system composed of a large, thick root; can have smaller lateral roots  Fibrous: a root system made up of many small, branching roots

 Tip of root contains the root cap and a meristem  Root Cap: mass of cells that form a protective covering for the meristem at the root tip; allows the root to penetrate the soil with minimal damage

 Root hairs project out of the epidermis and increase the surface area allowing for greater water and nutrient absorption  Root cortex is a region of parenchyma cells beneath the epidermis where carbohydrates can be stored and water can be transported fro the epidermis to the xylem  Endodermis: is the innermost layer of cells in the root cortex

 The endodermis cell walls are wrapped with a wax-like substance forming a continuous barrier called the Casparian strip. The Casparian strip prevents substances from passing through the spaces between the endodermal cells

 Vascular tissue is arranged differently in monocot roots and eudicot roots