Transcript Leaves
Leaves By: Becky McGuire Function • make food used by plants for growth & reproduction Parts Dicots • • • • • a. blade: broad, thin part of leaf b. petiole: thin stem attaching leaf to stem 1. sessile: leaves with no petiole c. midrib: large, central vein d. margin: edge of leaf Parts Dicots, continued • E. secondary vein: branches from main vein • F. tip: top of leaf • G. base: bottom of leaf Diagram of a Dicot Leaf Tip Secondary Midrib Vein Blade Petiole Margin Base Monocots • a. sheath: portion of leaf blade surrounding stem • b. ligule: “collar” extension of sheath curving around stem • auricles: appendages that surround stem at junction of blade and sheath Diagram of a Monocot Leaf Leaf Stem Ligule Auricles Sheath WHERE WILL YOU EVER USE THIS? • For identification of weeds and plants for fertilizer, pesticides, etc. Leaf Characteristics Simple • a. one blade per leaf • ex: grass, oak, apple Compound • a. several leaflets • ex: sumac, locust identification • shape, margin, tip, base (see handouts) venation: arrangement of veins in a leaf • 1. parallel: extend from base to tip of leaf in parallel lines • ex. Grasses/monocots • 2. dichotomous: forked veins, begin at base and go out from central point to tips • ex. Ferns, ginko • 3. pinnate: secondary veins extend from midrib • ex. Poplar • 4. palmate: principal veins extend from petiole • ex. Maple, sweetgum arrangement on stem • 1. alternate: leaves occur at alternate spots on stem; single leaf at each node • a. oak, beech • 2. opposite: leaves occur two at a node on opposite sides of stem • a. maple, ash, dogwood (MAD; only 3) • 3. whorled: 3 or more leaves at each node