Leaves Flashcards
Originate as primordia in buds
Leaves
Stalk : ________
Flattened blade : _________
Network of veins : _________
Petiole
Lamina
Vascular bundles
Leaves with a petiole are
Petiolate
Leaves without a petiole are
Sessile
It has a single blade
Simple leaves
It has their blades divided into leaflets
Compound leaves
They have leaflets in pairs along rachis.
Pinnately compound
They have all leaflets attached at same point of petiole.
Palmately compound
Trapping and storing of energy in sugar molecules that are constructed from water and carbon dioxide
Photosynthesis
● Tiny pores on lower surfaces of leaves
● Allow carbon dioxide to enter and oxygen to diffuse out
Stomata
● control water loss.
● Open or close pore of stomatal apparatus
Guard cells
Wastes from metabolic processes accumulate in leaves and are disposed of when leaves are shed.
Abscission
Evaporation of water from leaf surface
Transpiration
Root pressure forces water out hydathodes at tips of leaf veins in some plants.
Guttation
Arrangement of veins in a leaf or leaflet blade
Venation
● One primary vein (midvein) in an enlarged midrib
● Secondary veins branch from midvein
Pinnately veined
Several primary veins fan out from base of blade.
Palmately Veined
In monocots, primary veins are parallel. In dicots, veins are netted or reticulate. True or false?
True
Transversely, the leaf is made of:
Epidermis, Mesophyll, Vascular bundles
● Single layer of cells covering the entire surface of the leaf
● Devoid of chloroplasts
● Coated with cuticle
Epidermis
● Functions to protect tissues inside leaves
● Waste materials may accumulate in cells.
● Different types of glands may also be present
Epidermis
● Regulate gas exchange between leaf interior and atmosphere
● Regulate evaporation of water
● Open when guard cells are filled with water
Stomata
Where photosynthesis takes place
Mesophyll
● Compactly stacked, barrel-shaped parenchyma cells
○ Commonly in two rows
● Contains most of leaf’s chloroplasts
Palisade Mesophyll
● Loosely arranged parenchyma cells with abundant air spaces
● Allows free movement of carbon dioxide
Spongy Mesophyll
● Vascular bundles scattered in mesophyll.
● Consist of xylem and phloem surrounded by bundle sheath of thicker-walled parenchyma
Veins
● Usually do not have mesophyll differentiated into palisade and spongy layers
● Often have bulliform cells on either side of main central vein
Monocot Mesophyll
● Partly collapse under dry conditions
● Causes leaf to fold or roll
● Reduces transpiration
Bulliform Cells
● Receive less total light than sun leaves
● Compared to sun leaves
○ Larger and thinner
○ Fewer well-defined mesophyll layers and chloroplasts
○ Fewer hairs
Shade Leaves
● Thick, leathery leaves
● Fewer stomata or sunken stomata
● Succulent leaves or no leaves
● Dense, hairy leaves
Arid Regions
● Less xylem and phloem
○ Transpiration does not work here.
● Mesophyll not differentiated
● Large air spaces
Aquatic Leaves
● Curl around more rigid objects
● Help the plant to climb or to support weak stems
Tendrils
● Reduce leaf surface and water loss
● Protect from herbivory
Spines
They are modified stems arising in the axils of leaves of woody plants
Thorns
They are outgrowths from epidermis or cortex
Prickles
Succulent leaves store _______ ; Fleshy leaves store _______
Water ; carbohydrates
Leaves develop into urn-like pouches that become home of ant colonies.
Flower-Pot Leaves
● Leaves buried in ground, except for exposed end.
● End has transparent, thick epidermis and transparent water storage cells underneath.
Window Leaves
● Walking ferns produce new plants at leaf tips.
● Air plants make tiny plantlets along leaf margins
Reproductive Leaves
● Look like flowers
● At bases of flowers or flower stalks
Bracts
● Trap and digest insects
● Nitrogen and other elements are deficient in soil.
Insect-Trapping Leaves
Chlorophylls are _________.
Carotenoids are _________.
Anthrocynanin are _________
Green
Yellow or orange
Red
Cells of protective layer are coated and impregnated with suberin.
Abscission Zone
