Characteristics of Twigs and leaves Along with Leaf Structures 7TH GRADE SCIENCE

GENERAL TERMS leaf — a lateral outgrowth from the stem whose primary function is the manufacturing of food twig -- a young woody stem to which leaves and buds are attached branch -- a thicker, older woody stem to which twigs are attached trunk -- the main vertical stem of a treefruit — the seed-bearing portion of a plant deciduous — trees on which all leaves fall at the end of every season of growth evergreen — trees on which leaves remain attached for more than one year

twigs

Parts of a twig Petiole Node Internodes Lateral/axillary bud Terminal bud Terminal bud Scars Leaf Scar

Petiole A leaf stalk, it attaches the leaf to the stem.

the part of a twig between two nodes Node the place on a twig where a Internode the part of a twig between two nodes Node the place on a twig where a leaf is attached Node Internode

Lateral/axillary Bud a bud that is situated along the sides of a branch and not at the tip It may become next years branches or flowers

Terminal bud a bud that is at the tip of a stem or branch Where the branch can grow longer

Terminal Bud Scars Can determine the age of the twig by counting these

Leaf/Bud Scar the scar left on a twig when a leaf falls

Leaves

Functions of Leaves Manufacture food for the plant, through process of photosynthesis Equation for Photosynthesis: CO2 + H2O  C6H12O6 + O2 Photosynthesis only occurs when light is present

Leaf Terms Epidermis: outside layer of the leaf (leaf surface) Stomata: openings in the leaves where carbon dioxide comes in from the atmosphere (needed for photosynthesis)

Leaf Terms Transpiration: the loss of water vapor from the plant; most water is lost from the stomata, some through the cuticle layer.

Parts of a Leaf Lamina/blade Leaf Apex Midrib Petiole Stem Vein

Lamina/blade The blade of the leaf.

Leaf Apex The outer end of a leaf; the end that is opposite the petiole.

Midrib The central rib of a leaf, it is usually continuous with the petiole.

Petiole A leaf stalk, it attaches the leaf to a plant.

Stem The main support of the plant, also called the apex.

Vein One of the many vascular structures on a leaf. Veins provide support for the leaf, and transport both water and food through the leaf.

Veins Parallel Palmate Pinnate Up and down From one central location Off one main vein

Types of Leaves Simple Compound

Simple Simple Leaves are of one continuous leaf surface, not divided into separate segments.

Compound Compound leaves are composed of many smaller leaflets, each resembling a complete leaf in and of itself.

Types of Compound Leaves Palmate Odd Pinnate Even Pinnate

Palmate The leaflets are attached at one plane at the base.

Odd Pinnate Leaflets are on two opposite sides of the axis, with an odd number of leaflets, one at the tip.

Even Pinnate Leaflets are on two opposite sides of the axis, with an even number of leaflets, and paired at the tip.

Leaf Arrangement Alternate Opposite Whorled

Alternate Leaves are borne singly at each node.

Opposite Leaves are borne two at each node.

Whorled Three or more leaves are arranged in a circle around the stem.

Leaf Shape Heart Lance Oval Diamond Round

Heart Shaped The top of the leaf is pointed while the bottom of the leaf is uneven. Making a heart like shape.

Lance shaped Long and narrow

Oval shaped Have a rounded top and bottom.

Diamond Shape The tip is pointed while the base is rounded

Round shaped Completely rounded at the top and bottom

Leaf margins Smooth/entire Wavy Serrate (saw toothed) Doubly serrate lobed

Smooth/entire margin no kind of marginal division or nearly lacking marginal division

Wavy margin having a wavy up and down edge

Toothed (serrate) Margin having sharp, straight-edged teeth pointing to the apex

Double serrate margin primary teeth have smaller secondary teeth

Lobed Margins With Shallow, obtuse or rounded teeth scalloped