parenchyma
in higher plants, the fundamental tissue that is composed of thin-walled living cells that function in photosynthesis and storage
collenchyma
a group of enlongated, thick-walled plant cells that support the growth of leaves and stems
sclerenchyma
a type of plant tissue composed of cells that have thickened secondary cell walls that function in plant support
epidermis
the outer surface layer of cells of a plant or animal
cuticle
the waxy/fatty and watertight layer on the external wall of epidermal cells
tracheid
a thick-walled, cylindrical cell with tapered ends that is found in xylem and provides support and conducts water and nutrients
pit
in plants, the thin, porous areas of a tracheid cell wall
vessel element
in plants, one of the cellular components of a xylem vessel
vessel
in plants, a tubelike structure in the xylem that is composed of connected cells that conduct water and mineral nutrients; in animals, a tube/duct that carries blood or other bodily features
sieve-tube member
one of the component cells of a sieve tube, which is found mainly in flowering plants
sieve-tube
in the pholem of a flowering plant, a conducting tube made of a series of sieve-tube members stacked end to end
sieveplate
a region that connects 2 sieve cells and that has one/more sieve areas, which consists of clusters of pores through which the cytoplasm of the cells is connected and through which materials are transported
companion cell
a cell that gives rise to sieve tubes in angiosperms
meristem
a region of undifferentiated plant cells that are capable of dividig and developing into specialized plant tissues
apical meristem
the growing region at the tips of stems and roots in plants
lateral meristem
dividing tissue that runs parallel to the long axis of a stem or root
vascular cambium
in a plant, the lateral meristem that produces secondary xylem and pholem
cork cambium
a layer of tissue under the cork layer when cork cells are produced
taproot
a root that develops from the radicle of a plant embryo, grows vertically downward, and forms branches called lateral roots
fibrous root system
a system of adventitous roots of approx. equal diameter that arise from the base of the stem of a plant
adventitious root
a root that occurs in an unusual position, such as stems/leaves
root cap
the protective layer of cells that covers the tip of a root
root hair
an extension of the epidermis of a root that increases the root's surface area for absorption
cortex
in plants, the primary tissue located in the epidermis; in animals, the outermost portion of an organ
endodermis
the single layer of cells that surrounds the vascular tissue in the roots and in some stems of plants; the innermost layer of cortex in seed plants
pericycle
in plants, the outer portion of the central cylinder of vascular tissue
macronutrient
an element required in relatively large amounts
micronutrients
a chemical needed in very small amounts for plant growth, such as manganese, iron, and zinc
node
in biology, a joint between 2 adjacent sections in the stem of a plant where buds form and leaves/branches start to grow; usually marked by a knot or swelling
internode
the part of a plant stem between 2 consecutive nodes
bud
a shoot or flower that has immature leaves folded in the growing tip
bud scale
a modified leaf that forms a protective covering for a bud until it opens
pith
the tissue located in the center of the stem of most vascular plants and used for storage
wood
the hard substance composed mainly of xylem and found under the bark of the trunks and branches of trees and shrubs
heartwood
darker wood in the center of a tree
sapwood
light-colored near the outside of the trunk
bark
a tissue of dead cells that forms on the exterior of woody plants for protection
springwood
water is plentiful- vascular cambium for the xylem with cells that are wide and thin walled
summerwood
when water is limited- smaller cells and thicker walls
annual ring
in secondary xylem (wood), the growth ring formed in one season
source
a part of a plant that makes sugars and other organic compounds and from which these compounds are transported to other parts of the plant
sink
any place where a plant stores/uses organic nutrients such as sugars and starches
translocation
the movement of a segment of DNA from one chromosome to another, which results in a change in the position of the segment; also the movement of soluble nutrients from one part of a plant to another
pressure-flow hypothesis
an explanation for the movement of carbohydrates in the pholem of plants; holds that carbohydrates are actively transported into sieve tubes
transpiration
the process by which plants release water vapor into the air through stomata; also, the release of water vapor into the air by other organisms
cohesion-tension theory
an explanation for the movement of water up the stem xylem of tall plants; states that water is pulled up the xylem vessels by the cohesive force between the water molecules and the adhesion of the water molecules to the rigid vessel walls
tendril
an organ of climbing plants that grows in spiral form and wraps around another body to help support the plant
blade
the broad, flat portion of a typical leaf
petiole
the stalk that attaches a leaf to the stem of a plant
simple leaf
a leaf that has an undivideble blade
compound leaf
a type of leaf in which the blade is divided into leaflets
leaflet
one segment of a compound leaf
mesophyll
in leaves, the tissue between epidermal layers, where photosynthesis occurs
palisade mesophyll
in plants, the layer of vertically elongated cells that contain chloroplasts, located beneath the upper epidermis of leaves, and that participates in photosynthesis
spongy mesophyll
inside a leaf, the tissue that is made up of loosely arranged parenchyma cells that contain chloroplasts and are surrounded by air spaces that promote the diffusion of oxygen, carbon dioxide, and water throughout the leaf
vein
in bio, a vessel that carries blood to the heart
venation
the arrangement of veins on a leaf
parallel venation
a parallel arrangement of veins, typical of the leaves of monocots
net venation
a nonparallel branching network of veins that is typical of the leaves of dicots
guard cell
one of a pair of specialized cells that border a stoma and regulate gas exchange