LEAVES Coniferous VS Deciduous Which is Which Characteristics

LEAVES

Coniferous VS Deciduous

Which is Which?

Characteristics of Conifers • Needle shaped leaves • Seeds that develop inside cones • Evergreen – green year round • Gymnosperm, conifer, softwood • Examples: pine, spruce, hemlock, fir

Examples of conifers Balsam fir Fraser fir Red pine Douglas fir White pine Scotch pine

Conifer leaves • Needle like • Scale like

Conifer needles • Clusters • Singles

Deciduous Tree Characteristics • Broad flat leaves • Lose all leaves each year in the fall • Angiosperm (flowering plants), broadleaf, hardwood • Examples: oak, maple, beech, aspen, ash

Deciduous examples Red oak Black locust Elm White birch Honey locust beech Red maple Crimson king

Exceptions • Larch trees have cones and needles, but lose their leaves each year. • Yew trees have needle shaped leaves and are evergreen but have berries not cones. • Holly trees have broad flat leaves and it is evergreen.

Leaf Characteristics/I D

Leaf Characteristics-Deciduous 1. Leaf arrangement: whorl, alternate, opposite 2. Leaf type: simple or compound 3. Leaf margin: entire, lobed, toothed– others exist 4. Leaf texture: hairy, waxy, rough, smooth, thick, thin, etc. 5. Leaf shape: ovate, obovate, lanceolate, cordate, elliptical, etc. – others exist

1.

What is the leaf arrangement?

What is the leaf arrangement?

2. Leaf Type

Simple • Only one leaf blade • Joined by its stalk to the woody stem • Examples: maple, oak, aspen, beech Compound • Made up of several leaflets • Leaflets are joined to a midrib that is not woody • Examples: ash, walnut, sumac

Simple or Compound?

What is the leaf type?

3. Leaf Margins 1. Entire = margin lacks teeth (smooth) 2. Serrate = saw-tooth with the teeth pointing forward 3. Lobe = projecting part or segment of the leaf - Space between two lobes is a sinus - Example maple or oak

4. Leaf Texture hairy, waxy, rough, smooth, thick, thin, etc. Describe the “leaf” of the aloe plant

5. Leaf Shapes • Ovate = egg-like shape, broadest part below the middle • Obovate = shaped like an egg, broadest part above the middle • Lanceolate = much longer than wide • Cordate = shaped like a heart • Elliptical = have an ellipse shape, broadest part in the middle

External Leaf Structure

External Leaf Structure Tip Margin Blade Vein Spine Midrib Base Petiole

External Leaf Parts 1. The large broad part of a leaf is the leaf blade �Large surface area for photosynthesis �Supported by a system of veins that contain xylem and phloem 2. Main vein running down the middle is the midrib �Help position the blade in a way that it is facing a light source

External Leaf Parts 3. The leaf blade is connected to the stem by the petiole �Lifeline between the leaf and the rest of the plant �Water and minerals flow into the leaf blade and food flows out of the leaf blade through the petiole 4. The edge of the leaf blade is referred to as the margin �Wavy, toothed, lobed, and entire or smooth.

External Leaf Parts 5. On top of the leaf is a waxy non-cellular layer called the cuticle �Prevents water from escaping �Plants in bright arid conditions have thick cuticles to retain water 6. Veins �Contain xylem and phloem (stem cells that allow for movement of nutrients/waste)

Internal Leaf Structure

Internal Leaf Parts 1. The epidermis is the skin-like layer of cells on the top AND the bottom surface of the leaf – The epidermis may be one or many layers thick – Protective 2. Between the epidermal layers is the mesophyll – Photosynthetic occurs in mesophyll cells – Network of veins containing xylem and phloem tissues – 2 Types: • Palisade mesophyll – tightly packed cells standing on end directly beneath upper epidermis • Spongy mesophyll – loosely packed cells, form air spaces to hold products of photosynthesis, under palisade

What are the functions of the internal components of a leaf? 3. Leaves have openings in the epidermis called stomata - singular: stoma - Allow the diffusion of carbon dioxide, oxygen, and water. - Specialized cells called guard cells control the opening and closing of the stomata

4. Trichomes - Specialized cells that appear as hairs on the leaves of some plants - Reduce water loss by slowing air movement - Discourage some pests from devouring the leaves - Example: soybeans

Cuticle Palisade Epidermis Chloroplast Vein Xylem Spongy Layer Phloem Air Space Guard Cell Stoma Cuticle Epidermis

Additional Comments – Internal Structure • Chloroplast – Organism containing chlorophyll which is green and collects light energy • Xylem – Transports water and nutrients up the plant • Phloem – Transports sugars down the plant • Guard Cell – Controls moisture and gas exchange – Open when plant is well watered and closed when the plant is dry