leaves. coniferous vs deciduous which is which?
TRANSCRIPT
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 Douglas fir
Fraser fir Scotch pine
Red pine
White 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 Red maple
Black locustWhitebirch
Crimson king
Honey locust
beech
Elm
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 Characteristic
s/ID
Leaf Characteristics-Deciduous1. Leaf arrangement: whorl, alternate,
opposite2. Leaf type: simple or compound3. Leaf margin: entire, lobed, toothed–
others exist4. 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 Compound
• Only one leaf blade• Joined by its stalk to the
woody stem• Examples: maple, oak,
aspen, beech
• 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 forward3. 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 StructureTip
Margin
Vein
Spine
Midrib
Base
Blade
Petiole
External Leaf Parts
1. The large broad part of a leaf is the leaf bladeLarge 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 plantWater 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.
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)
External Leaf Parts
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
CuticleEpidermis
PalisadeChloroplast
SpongyLayer
Xylem
Phloem
Epidermis
Guard Cell
Stoma
Cuticle
Vein
Air Space
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