Ch 6 Flashcards
Leaf blade (Lamina)
the broad, expanded part of a leaf; not the petiole; flat, light-harvesting portion
Petiole
stalk that holds the blade out into the light
Sessile leaf base
leaves are small or very long and narrow, self-shading is not a problem
Sheathing leaf base
the leaf base wraps around the stem
Simple leaf
has a blade of just one part
Compound leaf
has a blade divided into into several parts
Leaflets
many small blades
Petiolule
the stalk that attaches a leaflet to the rachis of a compound
Rachis
the extension of the petiole in a compound leaf; all leaflets are attached to the rachis
Veins
bundles of vascular tissue; distribute water from the stem to the leaf; collects sugars produced by photosynthesis and carries them to the stem for use or storage
Reticulate Venation
netlike pattern of veins in a leaf, found primarily in leaves of dicots (broadleaf plants)
Parallel Venation
almost exclusively in monocot leaves, a pattern in which all veins run approximately parallel to each other, either from the base of the leaf to its tip or from the midrib to the margin
Abscission zone
the region at the base of an organ, such as a leaf or fruit, in which cells die and tear, permitting the organ to fall cleanly away from the stem with a minimum of damage
Leaf scar
the region on a stem where a leaf was attached prior to abscission
Epidermis
outermost layer of the plant primary body, covering leaves, flower parts, young stems and roots
Transpiration
loss of water vapor through the epidermis
Mesophyll
all tissues of a leaf except the epidermis
Palisade parenchyma
any part of leaf mesophyll in which the cells are elongate and aligned parallel to each other
Spongy mesophyll
any part of leaf mesophyll in which the cells are not aligned parallel to each other and are separated by large intercellular spaces
Mid-rib veins
the large, central vascular bundle of a leaf
Lateral veins
the major, large vascular bundles of a leaf, which are attached to the midrib or the petiole; larger than minor veins
Minor veins
smallest veins of a leaf, branching off lateral veins; there is no criterion that strictly distinguishes between minor and lateral veins
Bundle sheath
a set of cells, which may be parenchyma, collencyma, or sclerenchyma, that encases some or all of the vascular bundles of a leaf
Bundle Sheath Extension
a set of cells, usually fibers, that extends from the bundle sheath to the upper or lower (or both) epidermis of a leaf
Leaf Traces
vascular bundle that extends from the stem vascular bundles through the cortex and enters a leaf
Stipules
small flaps of tissue located at the base of a leaf, near its attachment to the stem; stipules may range from quite leaflike to small and inconspiculous
Leaf primordium
an extremely early stage in leaf development, when the leaf exists only as a pronounced bulging of the shoot apical meristem
Succulent leaves
permits plants to survive in the desert; thick and fleshy leaves which reduces surface-to-volume ratio and favors water conservation; consequence of reducing the capacity for carbon dioxide uptake
Sclerophyllous foliage leaves
must produce more sugars by photosynthesis than are used in their own construction and metabolism or the plant would lose energy every time it produced a leaf; leaves are soft, flexible, edible and less sclerenchyma
Leaves of conifers
leaves are sclerophylls; they have a thick cuticle, their epidermis and hypodermis cells have thick walls; always simple and only have a few forms; needle-shaped leaves
Bud scales
small specialized leaf, usually waxy or corky, that protects an unopened bud; protection; small and rarely compound
Spines
modified leaves of axillary buds; protection; ie cacti; no blade and are needle shaped
Tendrils
modified leaves; grow indefinitely and contain cells capable of sensing contact with an object; tendril touches something that side stops gorwing and the other side continues to elongate
Leaves with Kranz Anatomy
in C4 plants; have bundle sheaths composed of large chlorophyllous cells; ring of mesophylls cells surround the sheath; adapted to arid env
Insect traps
insectivory in habitats poor in nitrates and ammonia; trap leaves are either active traps that move during capture or passive traps incapable of moving
