Roots, Stems, & Leaves

Tissues 3 Main Tissues: Dermal Tissue: epidermal cells; outer covering of plant, like skin Vascular Tissue: contains xylem with tracheid cells & phloem Ground Tissue: cells between the dermal and vascular; have three types of cells Parenchyma: thin cell walls Collenchyma: strong flexible cell walls Sclerenchyma: extremely thick, rigid cell walls

Roots Two Type of Roots Taproots: found in dicots; grow long & thick; reach water far below Fibrous Roots: have many branching roots of same size Structure = epidermis on outside, vascular tissues in middle, & ground tissues in middle Root Hairs: extensions that allow roots to absorb more water

Purpose of Roots What is their job: Uptake nutrients and water Move nutrients to plant & vascular tissues Keep high pressure to move water & nutrients up the plant

Stems Three important functions: Produce leaves, branches, & flowers Leaves connected at Nodes & start as Buds Hold leaves up to the sunlight Transport substances from roots to leaves Monocot vs Dicot Stems Monocot = dispersed vascular bundles Dicot = vascular bundles in circle

Stem of Trees Wood is layers of xylem Heartwood = middle of tree that no longer has water flowing through it Sapwood = surround the heartwood & transports water through xylem Bark = outer layer of stem

Leaves Purpose: to absorb sunlight and perform photosynthesis Green color because of chlorophyll Blade: flattened section; collects sunlight Petiole: stalk that blade attaches to

Photosynthesis Photosynthesis occurs in mesophyll Palisade mesophyll: cells that absorb light Spongy mesophyll: has air sacs connected to stomata Stomata: pore-like structures that allow carbon dioxide and oxygen to enter and leave the leaf Guard Cells: two of these cells make 1 stomata Stomata stay open during photosynthesis, but close when losing too much water