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Chapter 23: Roots, Stems, and Leaves

Terms in this set (44)

epidermal cell
cell that makes up the dermal tissue, which is the outer covering of a plant
cuticle
in plants, a thick waxy layer on exposed outer surfaces of cells that protects them against water loss and injury
trichome
tiny cellular projection on the surfaces of some leaves that helps protect the leaf and also gives it a fuzzy appearance
vessel element
in angiosperms, xylem cell that forms part of a continuous tube through which water can move
sieve tube element
phloem cell that is joined end-to-end to similar cells to form a continuous sieve tube
companion cell
phloem cell that surrounds sieve tube elements
parenchyma
type of ground-tissue cell with a thin cell wall and large central vacuole
collenchyma
type of ground tissue cell with a strong, flexible cell wall; helps support larger plants
sclerenchyma
type of ground-tissue cell with an extremely thick, rigid cell wall that makes ground tissue tough and strong
meristem
cluster of tissue that is responsible for continuing growth throughout a plant's lifetime
meristematic tissue
plant tissue found only in the tips of shoots and roots; responsible for plant growth
apical meristem
group of undifferentiated cells that divide to produce increased length of stems and roots
differentiation
process in which cells become specialized in structure and function
taproot
primary root found in some plants that grows longer and thicker than other roots
fibrous root
part of a root system in which roots branch to such an extent that no single root grows larger than the rest
root hair
tiny projection from the outer surface, or epidermis, of a root
cortex
spongy layer of ground tissue just inside the epidermis of a root
endodermis
layer of cells that completely encloses vascular tissue
vascular cylinder
central region of a root that includes the vascular tissue—xylem and phloem
root cap
tough structure that protects a root as it forces its way through the soil
Casparian strip
waterproof strip that surrounds plant endodermis cells
node
point on a stem where a leaf is attached
internode
region between nodes on plant stems
bud
plant structure containing undeveloped tissue that can produce new stems and leaves
vascular bundle
plant stem structure that contains xylem and phloem tissue
pith
parenchyma cells inside the ring of vascular tissue in dicot stems
primary growth
type of plant growth that occurs at the tips of roots and shoots
secondary growth
pattern of plant growth in which stems increase in width
vascular cambium
lateral meristematic tissue that produces vascular tissues and increases the thickness of the stem over time
cork cambium
lateral meristematic tissue that produces the outer covering of stems
heartwood
older xylem near the center of a woody stem that no longer conducts water
sapwood
area in plants that surrounds heartwood and is active in fluid transport
bark
tree structure that includes all tissues outside the vascular cambium, including phloem, the cork cambium, and cork
blade
thin, flattened section of a plant leaf that collects sunlight
petiole
thin stalk by which a leaf blade is attached to a stem
mesophyll
specialized ground tissue that makes up the bulk of most leaves; performs most of a plant's photosynthesis
palisade mesophyll
layer of tall, column-shaped mesophyll cells just under the upper epidermis of a leaf
spongy mesophyll
loose tissue beneath the palisade layer of a leaf; has many air spaces between its cells
stoma
opening in the underside of a leaf that allows carbon dioxide and oxygen to diffuse into and out of the leaf
guard cell
specialized cell in the epidermis of plants that controls the opening and closing of stomata by responding to changes in water pressure
transpiration
loss of water from a plant through its leaves
adhesion
attraction between molecules of different substances; in plants, attraction between unlike molecules
capillary action
tendency of water to rise in a thin tube
pressure-flow hypothesis
hypothesis that considers plants in terms of where they produce and use materials from photosynthesis
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