LEAF MORPHOLOGY AND ANATOMY Flashcards
Main photosynthetic organs of plants and as the site of transpiration
Leaves
Most leaves are ….
Optimal for ….
Thin and Flat
Diffusion of gases such as CO2 andO2
broad, flat portion of a leaf
Blade
Edge of the leaf
Margin
leaflike outgrowths usually
present in pairs at the base of the petiole
Stipules
veins along the midline which
usually possess the primary vein.
Midrib
veins that branched out
from the primary vein
Secondary Vein
emerging buds observed
between the stem and petiole
Auxiliary buds
The pattern of division of a leaf into discrete components or segments is termed
Leaf Type
One bearing a single continuous blade
Simple leaf
Divided into two or more, discrete leaflets
Compund leaf
Leaf arrangement
Phyllotaxy
refers to one leaf or other structure per node (upper left).
Alternate
describes two leaves or other structures per node, i.e., on opposite sides of a stem or central axis (upper right).
Opposite
(opposite in two ranks) is termed for opposite leaves or other structures at right angles to preceding pair (lower left).
Decussate
having three or more leaves or other structures per node (lower right).
Whorled
It covers both the upper and the lower surface
Epidermis
Refers to the tissue present in between the upper and lower epidermis; photosynthetic tissue of the leaf and divided into two regions
Mesophyll
It lies below the upper epidermis;
Made up of elongated cells arranged vertically, forming an angle of 90′′ with the upper epidermis and these cells have numerous chloroplasts and take an active part in photosynthesis. The cells do not have intercellular spaces in between them and are closely packed.
Palisade mesophyll
Lies below the palisade parenchyma
and made up of round or oval cells, which are irregularly arranged without any particular arrangement. The cells possess large intercellular spaces in between them for
gas exchange and heat dissipation
Spongy Mesophyll
• These are leaves or part of the leaves that have specialized functions other than its primary purpose
• These modifications resulted to adapt their habitat, protection from predators, support the plant, attract pollinators, and more
Leaf Modification
• Refer to one of the leaves resembling scales that form the sheath of a plant bud
• Protects the young buds (e.g., new leaf or apical meristem)
• Usually found in trees in temperate countries or diagnostic characteristic of a plant family (Moraceae)
Bud scales
• Modified petiole or leaf stems that appear like a leaf
• Widened petiole or leaf stem function as a normal leaf for photosynthesis
• Found in Acacia and Citrus
Phyllode
• Refers to the large sheathing bract enclosing the flower cluster of certain plants, especially the spadix of aroid (Araceae) and palms (Arecaceae)
• Attract pollinators particularly bright colored spathe
Spathe
• Refer to the structurally a short stem with fleshy leaves or leaf bases (leaf scales)
• It functions as food storage organs during dormancy
• Particularly in the family of Alliaceae
Bulb
• Refer to a coiled and twining leaf or leaf part, usually a modified rachis or leaflet
• Function for overall support of the plant particularly climbing up
• Particular in Garden Peas
Leaf Tendril
• Refers to the modified sharp-pointed leaf or leaf part
• Function to reduce water loss and to deter herbivores
•Cactaceae, Agavaceae and Bromeliaceae Family
Spines
• Refer to the leaves with thick fleshy tissues
• Function for water storage particularly an adaptation to arid environme
Succulents
• Refers to the modification of the leaf which can produce plantlets asexually through the development of miniature plantlets at the edges of their leaves
• Bryophyllum/ Kataka-taka
Reproductive leaf
• Leaf modification which are brightly colored leaves
• Function as a flower petal to attract pollinators • Found in plants with flowers that are inconspicuous or very small
• Euphorbia red bracts Mussaenda (Donya Aurora) pinkish bracts
Showy Bracts
• Leaves with modifications on their morphoanatomy that have high air spaces
• Function for buoyancy on the water surface
• Eichhornia/ Water hyacinth
Floating Leaves
• Morphologically shaped like a container or pitcher
• It bears an internal fluid and functions in the capture and digestion of insects or small animals
Pitfall Trap Leaves
• Leaves with numerous, sticky, glandular hairs or bristles which are adhesive and comparable to a “flypaper”
• Function in capturing and digesting insects and small animals
Tentacular Leaves
• Leaves that mechanically move after being triggered, in the process capturing and digesting insects or small animals
• Venus Fly Trap
• Waterwheel Plant
Snap Trap Leaves
Is one leaflets arranged either oppositely or alternately along central axis, the rachis
Pinnately compound leaf
A pinnate leaf has a thermal leaflet or had odd numbers leaflet
Odd-pinnate
Lacks terminal leaflet or have even number leaflet
Even-pinnate
Compound leaf with three orders of axes
Tripinnate
Compound leaf in which four or more leaflets arise from a common point
Palmate
