Chapter 7 Flashcards
Leaves
All leaves originate as
primordia in the buds
Petiole
Stalk that attaches leaf to twig
Blade/Lamina
Flattened actual leaf part, contains a network of veins called vascular bundles
Leaves that lack petioles are called
sessile
deciduous
The leaves of these trees live only one year.
Simple Leaf
has a single blade
Compound Leaf
the blade is divided various ways into leaflets
Regardless of the number of leaflets, a compound leaf still has
a single axillary bud at its base, the leaflets do not
Pinnately Compound
have the leaves in pairs along an extension of the petiole called the rachis
Rachis
Extension of the Petiole
Palmately Compound
have all the leaflets attached at the same point at the end of the petiole
Stomata
primarily found on the bottom of the leaf, small pores that play an essential role in gas exchange
Stomatal Apparatus consists of
a pore bordered by a pair of sausage shaped guard cells. Controls water loss when guard cells inflate or deflate
Transpiration
Most water evaporates in vapor form into the atmosphere through this process
Hydathodes
Found at the tips of leaf veins
Root openings force
Liquid water out of hydathodes, this is called guttation
Nodes
Region at which the leaf is attached to the stem
Internodes
Stem region between nodes
Pinnately veined
One primary vein
Midrib
Primary vein of pinnately veined leaves.
Palmately veined
Several primary veins fan out from the base of the blade
Netted/reticulate venation
The branching arrangement of veins in dicots
Dichotomous Venation
Veins fork evenly and progressively from the base of the blade to the opposite margin
Mesophyll
Region where photosynthesis takes place
Palisade mesophyll
Comprised of parenchyma cells that are usually aligned in two rows.contains 80% of the leafs chloroplast
Spongy mesophyll
Loosely arranged parenchyma cells with abundant air spaces between them. Play a role in gas exchange
Chlorenchyma
Parenchyma tissue with chloroplasts.
Veins (vascular bundles)
Consist of xylem and phloem tissues.
Bundle sheath
Surround the vascular bundles with a thicker walled parenchyma cells
Monocot veins
Parallel
Bulliform cells
Under dry conditions, the bulliform cells partly collapse, causing the leaf blade to fold or roll.
Modifications to an arid leaf
Sunken stomata, thick cuticle, and a layer of thick walled cells (hypodermis) beneath the epidermis
Leaves of aquatic plants
Have considerably less xylem and phloem
And the mesophyll, which isn’t divided into spongy and palisade, have larger air spaces
Tendrils
Modified leaves that climb up more rigid objects to reach sunlight
Spines
Reduce water loss
Protect from browsing animals
Thorns
Spine like objects that arise in the axils of leaves of woody plants, modified stem more than modified leaf.
Prickles
Neither leaves nor stems, but rather outgrowths from the epidermis or cortex
Succulent leaves
Leaves that are modified for water retention
Flower pot leaves
Leaf pods that become the home of ant colonies. Ants carry dirt in, allowing the leaf to grow roots, the ants die and provide fertilizer for plant.
Window leaves
Mostly underground leaf with a mostly transparent covering at the ground surface. This transparent covering allows light to directly hit the chloroplasts
Color of: Chloroplasts
Green
Color of: Carotenes
Yellow
Color of: Santhophylls
Pale yellow
Abscission
The process by which leaves are shed
