Lab 3 Flashcards
secondary structure
structure that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken
occurs in most seed plants; monocots usually lack secondary growth
dedifferentiation
transient process by which cells become less specialized and return to an earlier cell state within the same lineage
results in increase in cell potency, meaning that, following dedifferentiation, a cell may possess the ability to re-differentiate into more cell types; dedifferentiation often occurs in response to injury or stress, allowing cells to regenerate and differentiate into new cell types
phellogen/cork cambium
type of lateral meristem in plants responsible for producing phellem toward the outside and sometimes phelloderm toward the inside; contributes to the formation of the outer protective tissue layer called periderm
phelloderm
parenchyma tissue produced inwardly by the phellogen during secondary growth; located between the phellem and the secondary phloem
phellem/cork
outer protective tissue produced by phellogen during secondary growth in plants; forms the outermost layer of the periderm
periderm
protective tissue that replaces the epidermis in older stems and roots during secondary growth; consists of phellem, phellogen, and sometimes phelloderm
lenticel
small, raised area in the bark of woody stems and roots that allows for gas exchange between the internal tissues and the external environment
rhytidome
outermost layer of bark on older woody stems and roots, consisting of dead tissues such as phellem, phellogen, and phelloderm
intercellular space
space between plant cells where gases, water, and nutrients can move freely
storage parenchyma
parenchyma cells in plants that store reserve materials such as starch, oils, and proteins
interfascicular cambium
type of lateral meristem found between the vascular bundles in some plants, responsible for producing secondary xylem and phloem during secondary growth; differentiates from parenchyma or collenchyma cells located between the vascular bundles
fascicular cambium
a lateral meristem found within vascular bundles in plants, responsible for producing secondary xylem and phloem during secondary growth; differentiates from procambium located between the primary xylem and the primary phloem of individual vascular bundles
fusiform initial
elongated tapering cells that give rise to all cells of the vertical system of the secondary phloem and xylem (secondary tracheary elements, fibres, and sieve cells and the associated companion cells)
ray initial
isodiametric cells - shorter than fusilorm initial cells - that produce the vascular rays, which constitute the horizontal system of secondary tissues
secondary xylem
wood formed by the vascular cambium during secondary growth, consisting primarily of tracheids and vessel elements that conduct water and provide structural support
primary xylem
first-formed xylem tissue in a plant, derived from the procambium during primary growth
simple pit
small, simple opening in the cell wall of adjacent plant cells, allowing for the passage of water and solutes between cells
bordered pit
type of pit in the cell wall of certain plant cells, characterized by a thickened, often elaborate border that helps regulate the flow of water between cells
torus
structure found within bordered pits, consisting of a thickened area in the center of the pit membrane; prevents air from spreading between tracheids
early wood
portion of a tree growth ring formed during the early part of the growing season, characterized by larger, thinner-walled cells
late wood
portion of a tree growth ring formed during the later part of the growing season, characterized by smaller, thicker-walled cells
growth ring
distinct layer of wood formed during one annual growing season, visible as a ring in the cross-section of a tree trunk
annual ring boundary
boundary between adjacent growth rings in the wood of a tree, representing the end of one growing season and the beginning of the next
ring-porous wood
type of wood in which the size of the conducting vessels varies significantly between early and late wood, resulting in the formation of distinct growth rings
diffuse-porous wood
type of wood in which the size of the conducting vessels remains relatively uniform throughout the growth rings, without distinct differences between early and late wood
sapwood
outer, living portion of wood in a tree, responsible for conducting water and nutrients from the roots to the leaves
hardwood
wood of broad-leaved dicotyledonous trees, such as oak, beech, ash, as distinguished from the wood of a conifer
pith/medullary ray
radial structures extending from the pith to the bark, consisting of parenchyma cells that transport water and nutrients radially through the stem
ray
radial structure extending from the pith to the bark, consisting of parenchyma cells that transport water and nutrients radially through the stem
pith/medulla
central, spongy tissue found in the center of stems and branches, surrounded by vascular tissues
secondary phloem
phloem tissue produced by the vascular cambium during secondary growth, responsible for conducting sugars and other organic nutrients throughout the plant
primary phloem
first-formed phloem tissue in a plant, derived from the procambium during primary growth
ray dilatation
radial expansion of rays in woody plants, often occurring during periods of active growth
resin canal
tubular structures found in the tissues of some plants, especially conifers, responsible for producing and transporting resin
tree
woody perennial plant typically characterized by a single main stem or trunk, supporting branches and leaves above ground
shrub
woody plant with multiple stems, usually shorter than a tree and often branching close to the ground
herb
non-woody plant with a soft stem that dies back to the ground at the end of the growing season
heartwood
inner, older, non-living wood in the center of a tree trunk or branch, often darker in color and denser than the surrounding sapwood, due to the accumulation of extractives and deposition of compounds like tannins and resins
