Leaves and Tree Identification

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Leaves and Tree Identification Leaves are the
best way to identify a tree Simple leaf parts
1. apex - tip 2. margin- edges 3. base -
bottom 4. petiole - stem 5. mid-rib- middle
vein 6. lateral
vein side veins
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Leaf Identification

• There are 6 ways to identify a leaf
• 1. According to Petiole
• Petiolated leaves that have a petiole
• Sessile blade extends directly from the stem

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2. According to the blade

• Simple leaves Undivided blade
• Compound leaves Fragmented blades.

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3. According to the edge

• Entire smooth margin
• Sinuate little curves with smooth edges
• Dentate little teeth at the margin
• Serrate bent / saw like teeth at margin
• Lobed have divisions that do not arrive at the
  center.

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4. According to the shape of the blade
Elliptic leaves remembering to a
ellipse. 2 or 3 times longer than
wide Lanceolate leaves spear-shaped.
Gradually extending at the base and
lessening to the apex. Acicular leaves
needle-shaped. Several times longer
than wide ending sharply at the apex.

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Shape of the leaf

• Ovate leaves eggshaped, wider at the base
• Cordate leaves heart-shaped More extended at
  the base than the ovate type and with a notch
• Hastate - Wider at the base but with lobes ending
  sharply.
• Linear - strip-shaped. Several times longer than
  wide. Not pointed at the apex like in the
  acicular type.

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5. According to veins

• Parallel run at the same distance from each
  other
• Pinnate Main nerve from which other veins
  extend
• Palmate nerves diverge from a central point.

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6. According to arrangement along stem

• alternate springing one per node at different
  levels of the stem.
• opposite two per node, facing opposite sides of
  the stem.
• whorled Several leaves disposed at the same
  level around the stem.
• rosulate forming a rosette, like a ring around
  the stem.

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ranspiration Note 18 leaves of
plants have tiny holes (stomata) open stomata
allows gas and water to leave the plant loss
of water vapor thru stomata is transpiration
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How does water move? - water is pulled up because
loss of water from leaves causes a suction that
draws water up through xylem from the roots to
the leaf - more than 90 of water taken in is
lost this way
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How does plant regulate water loss? - stomata are
surrounded by guard cells that open and close
with water pressure - when guard cells take in
water, they swell and cause the stoma to open -
when plant is dehydrated, guard cells become
thinner, closing the stoma Stoma must open
sometimes to collect carbon dioxide for
photosynthesis
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Open stoma see swollen guard cells