leaves leaf homologies identification tree shape
TRANSCRIPT
LeavesLeaves
Leaf HomologiesLeaf Homologies
IdentificationIdentification
Tree shapeTree shape
Leaf HomologiesLeaf Homologies
Each leaf has a very different shape and function, yet all are homologous structures, derived from a common ancestral form.
What are Homologies?What are Homologies?
Shared similarities between organisms Shared similarities between organisms that are derived from common ancestors that are derived from common ancestors
Broadleaf or Conifer?Broadleaf or Conifer?
BROADLEAF (tree with leaves that are thin, flat & usually shed annually)
CONIFER (tree that bears cones and has needle-like or scale-like leaves)
ConifersConifers
Needle-likeNeedle-like SINGLY
FLAT length
SQUARE or 4-SIDED
Color BUNDLES OR
CLUSTERS DECIDUOUS EVERGREEN
# of needles held in BUNDLES
Scale-like Scale-like &&
Awl –likeAwl –like
Broadleaf TreesBroadleaf Trees
What external features can help What external features can help identify leaves / trees?identify leaves / trees?
Leaf shapeLeaf shape Leaf arrangementLeaf arrangement Leaf divisionLeaf division VenationVenation Tree shapeTree shape
Leaf shapeLeaf shape
Leaf arrangementsLeaf arrangements
Alternate
Each node has one leaf
Whorled
One node producing three or more leaves
Basal
Leaves originating in a cluster at the stem’s base
Opposite
Two nodes opposite each other on the stem, one leaf arising from each node
Leaf Arrangement—Opposite vs. Alternate
Leaf marginsLeaf margins
What is a leaf margin???
The MARGIN of a leaf is the leaf edge.
Some broadleaf trees have leaves with smooth edges or ENTIRE MARGINS.
Some broadleaf trees have LOBED LEAVES,
leaves with projections that shape the edge of the leaf.
Some broadleaf trees have TOOTHED MARGINS
or
Serratedcharacterized by a saw-like edge on
the leaf.
Leaf DivisionSimple vs. Compound Leaves. What is a leaflet?
Leaf divisionLeaf division
Simple Leaves•Single blade
Compound Leaves•Blade divided into leaflets
VenationVenation
1) Net 2)Parallel
Tree shapeTree shape