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Chapter 7 - Leaves - Coggle Diagram
Chapter 7 - Leaves
External Structure Of Foliage Leaves
Leaves need a balance of various traits
Leaf blade - light harvesting portion
Dorsal surface - lower side of leaf blade
Ventral surface - upper side of leaf
Petiole - stalk holding leaf to light
Leaf without is sessile leaf
Monocot foliage usually long and tapered
Leaves wrap around stem and make sheathing leaf base
Simple/compound leaves
Compound - blade divided into several parts
many small leaflets
an extension of the petiole called the rachis through a petiolule
Simple - blade of just one part
Veins are bundles of vascular tissue
in basal angiosperms and eudicots veins occur in patern called reticulate venation
In monocots the occur in parallel venation
Abscission zone cuts off leaf when it is no longer helpful
Morphology and Anatomy of Other Leaf
Types
Succulent leaves
thick and fleshy shape
Favor water conservation
Few airspaces in mesophyll
Sclerophyllous Foliage Leaves
Perennial leaves
thick and waxy cuticle
Leaves of Conifers
Most are sclerophylls
Always simple leaves
Mostly perennial
Bud Scales
protective scales of apical meristems
Spines
Modified leaves of axillary buds
Serve as protection
Tendrils
modified leaves that sense contact
Leaves with Kranz anatomy
Lack palisade parenchyma and spongy mesophyll
have prominent bundle sheaths made of large chlorophyllous cells
Insect Traps
ability to trap and digest insects
used to obtain nitrogen
Internal Structure of Foliage Leaves
Epidermis - outermost layer
Transpiration is the loss of water through this layer
Can be covered in trichromes
Mesophyll - ground tissues interior to the epidermis
Upper surface of most leaves is palisade parenchyma
main photosynthetic tissue
Lower portion of the leaf is the spongy mesophyll
Vascular Tissues - layer between palisade parenchyma and spongy mesophyll
Midrib - area from which lateral veins emerge
Bundle sheath - a sheath of fibers surrounding primary phloem and xylem
bundle sheath extension - mass of fibers above or below veins
Petiole - part of the leaf that is the transition between stem and the lamina
Stipules - small flaps at base of petiole
large plants can contribute to photosynthesis
Protect shoot apical meristem
Concepts
Leaves come in many forms
Optimal leaves are flat and thin
Initiation and Development of Leaves
Basal Angiosperms and Eudicots
leaves are only produced through shoot apical meristem
Leaf Primordium - protrusion of cells growing interior to the protoderm
Monocots
like other but apical meristem cells growth with leaf primordium
