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Lecture 9: Leaf Morphology (Common terms (Compound leaf types (Pinnately…
Lecture 9: Leaf Morphology
Common terms
Exstipulate
(No stipule)
Stipulate
(With stipule)
Sessile
(No petiole)
Clasping base
Abaxial leaf surface: underneath
Adaxial leaf surface: top
Simple leaf: A leaf with only one blade, or lobed leaf in which separates parts that do not reach down to the midrib
Compound leaf: A type of leaf with the blade divided into two or more separate parts called leaflets
Compound leaf types
Pinnately compound: Leaflets on an axis that is a continuation of the petiole
Palmately: Leaflets arise from a common point at the end of petiole
Leaf arrangement
Alternate
Opposite
Whorled (Spiral)
Leaf shapes
Leaf venation
Parallel venation
Primary veins run approximately parallel to one another
Generally found in monocots
Netted venation
Veins are branched to resemble a net
General characteristics of dicots
Palmately netted: Several major veins radiating out from one point
Pinnately netted: Major veins branching off along the entire length of the main vein.
Leaf symmetry
Symmetry: when divided in half, the two halves of the leaf show similarities between them
Asymmetry: The two halves of the simple leaf are not exactly the same
Heterophylly
Changes in the leaf form induced by the envt.
Dimorphism
Production of two different shapes of leaf during the life of the plant
Juvenile and adult leaves, where juvenile leaves are bipinnate leaves and the adult leaves are phyllode
Heteroblasty
a change in progression of leaf shape along a shoot at some stage of development
Ansiophylly
Leaves of different sizes or shape occur at the same node
Ptyxis
Folding of individual leaves or contortion of a single leaf
Drosophyllum lusitanicum
(Leaves rolled outwards)
Nelumbo nucifera
(involute folding)
Vernation
The packing of leaves together in a bud (or prefoliation)