Chapter 4 Flashcards
Meristematic Tissues
Meristematic tissues, or simply meristems, are tissues in which the cells remain forever young and divide actively throughout the life of the plant.
Meristems
The meristem is a type of tissue found in plants. It consists of undifferentiated cells capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells continue to divide until a time when they get differentiated and then lose the ability to divide.
parenchyma
Parenchyma forms the bulk of plant ground tissue, where they may be specialised to function in photosynthesis, storage, or transport. Parenchyma is integral to vascular tissue, where it provides a route of exchange for materials within and between the xylem and the phloem.
phloem
the vascular tissue in plants that conducts sugars and other metabolic products downward from the leaves.
xylem
xylem, plant vascular tissue that conveys water and dissolved minerals from the roots to the rest of the plant and also provides physical support.
sclerenchyma sclereids
Sclereids are a reduced form of sclerenchyma cells with highly thickened, lignified cellular walls that form small bundles of durable layers of tissue in most plants. The presence of numerous sclereids form the cores of apples and produce the gritty texture of guavas.
sclerenchyma fibers
Sclerenchyma fibers can be found below the epidermis of monocotyledons, organized in two or three layers of cells. They are known as cortical fibers. Perivascular sclerenchyma fibers are found protecting vascular bundles.
sclerenchyma
strengthening tissue in a plant, formed from cells with thickened, typically lignified, walls.
Plant epidermis
epidermis, in botany, outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant. The epidermis and its waxy cuticle provide a protective barrier against mechanical injury, water loss, and infection
Periderm
In botany, the term periderm is the outer covering of certain plants, especially woody plants. It is the outermost layer of the bark made up of cork cells, cork cambium, and phelloderm. It replaces the epidermis of the stems and roots of woody plants.
Secretory tissues
The tissues that are concerned with the secretion of gums, resins, volatile oils, nectar latex, and other substances
meristem
(mair′uh-stem) a region of undifferentiated cells in which new cells arise
apical meristem
(ay′pi-kul mair′i-stem) a meristem at the tip of a shoot or root
protoderm
(proh′tuh-durm) the primary meristem that gives rise to the epidermis
procambium
(proh-kam′bee-um) a primary meristematic tissue that differentiates into primary xylem and phloem
primary tissue
(pry′mer-ee tish′yu) a tissue produced by an apical meristem (e.g., epidermis, cortex, primary xylem and phloem, pith)
lateral meristem
(lat′uh-rul mair′uh-stem) region in a plant that produces tissue that increases the girth of roots and stems
vascular cambium
(vas′kyu-lur kam′bee-um) a narrow, cylindrical sheath of cells that produces secondary xylem and phloem in stems and roots
cambium
(kam′bee-um) a meristem producing secondary tissues; see vascular cambium, cork cambium
cork cambium
(kork kam′bee-um) a narrow cylindrical sheath of cells between the exterior of a woody root or stem and the central vascular tissue; it produces cork to its exterior and phelloderm to its interior; it is also called phellogen
node
(nohd) region of a stem where one or more leaves are attached
parenchyma
(puh-ren′kuh-muh) thin-walled cells varying in size, shape, and function; the most common type of plant cell
chlorenchyma
(klor-en′kuh-mah) tissue composed of parenchyma cells that contain chloroplasts
sclerenchyma
(skluh-ren′kuh-muh) tissue composed of lignified cells with thick walls; the tissue functions primarily in strengthening and support
lignin
(lig′nin) a polymer with which certain cell walls (e.g., those of wood) become impregnated
sclereid
(sklair′id) a sclerenchyma cell that usually has one axis not conspicuously longer than the other; it may vary in shape and is heavily lignified
xylem
(zy′lim) the tissue through which most of the water and dissolved minerals utilized by a plant are conducted; it consists of several types of cells
vessel element
ves′uhl el′uh-mint) a single cell of a vessel
vessel
(ves′uhl) one of usually very numerous cylindrical “tubes” whose cells have lost their cytoplasm; occur in the xylem of most angiosperms and a few other vascular plants; each vessel is composed of vessel members laid end to end; the perforated or open-ended walls of the vessel members permit water to pass through freely
perforation plate
(per′for-ey-shun playt) the end walls of xylem vessel elements with openings through which water flows
tracheid
(tray′kee-id) a xylem cell that is tapered at the ends and has thick walls containing pits
ray
(ray) radially oriented tiers of parenchyma cells that conduct food, water, and other materials laterally in the stems and roots of woody plants; they are generally continuous across the vascular cambium between the xylem and the phloem; the portion within the wood is called a xylem ray, while the extension of the same ray in the phloem is called a phloem ray
phloem
(flohm) the food-conducting tissue of a vascular plant
sieve tube member
siv t(y)oob mem′bur) a single cell of a sieve tube
companion cell
(kum-pan′yun sel) a specialized cell derived from the same parent cell as the closely associated sieve tube member immediately adjacent to it (in angiosperm phloem)
sieve tube
(siv t(y)oob) a column of sieve tube members arranged end to end; food is conducted from cell to cell through sieve plates
sieve plate
(siv playt) an area of the wall of a sieve tube member that contains several to many perforations that permit cytoplasmic connections between similar adjacent cells, the cytoplasmic strands being larger than plasmodesmata
callose
Callose is a plant polysaccharide. Its production is due to the glucan synthase-like gene in various places within a plant. It is produced to act as a temporary cell wall in response to stimuli such as stress or damage.
velamen root
(vel′uh-min root) an aerial root with a multilayered epidermis believed to function in retarding moisture loss
cutin
(kyu′tin) the waxy or fatty substance of which a cuticle is composed
cuticle
(kyut′i-kul) a waxy or fatty layer of varying thickness on the outer walls of epidermal cells
trichome
(trahy′ kohm) an outgrowth from the epidermis of plants
stoma
(pl. stomata) (stoh′muh; pl. stoh′mah-tuh) a minute pore or opening in the epidermis of leaves, herbaceous stems, and the sporophytes of hornworts (Anthoceros); it is flanked by two guard cells that regulate its opening and closing and thus regulate gas exchange and transpiration
guard cell
(gahrd sel) one of a pair of specialized cells surrounding a stoma
gland
(gland) a small body of variable shape and size that may secrete certain substances but that also may be functionless
periderm
(pair′uh-durm) outer bark; composed primarily of cork cells
cork
(kork) tissue composed of cells whose walls are impregnated with suberin at maturity; the outer layer of tissue of an older woody stem; produced by the cork cambium
suberin
(soo′buh-rin) a fatty substance found primarily in the cell walls of cork and the Casparian strips of endodermal cells
lenticel
(lent′uh-sel) one of usually numerous, slightly raised, somewhat spongy groups of cells in the bark of woody plants; lenticels permit gas exchange between the interior of a plant and the external atmosphere
secretory cell, tissue
(see′kruh-tor-ee sel, tish′yu) cell or tissue producing a substance or substances that are moved outside the cells
Which is not a major group of plant organs?
Seeds.
If a plant initially grows rapidly, but does not undergo secondary growth, which meristem is likely not functioning as it should?
Lateral.
A section of plant tissue contains two different cell types. Based on this information, the section can be classified as which of the following?
Complex tissue.
simple tissues
Parenchyma, Collenchyma, Sckerebchyma
A section of tissue was cut from the stem of an herbaceous plant, just beneath the epidermis. Examination of the section revealed living cells with unevenly thickened cell walls. The section is an example of what tissue type?
Collenchyma tissue.
Features of Parenchyma
Function in photosynthesis or in food/water storage, live cells with thin, pliable cell walls
Features of Collenchyma
Provides flexible support, often occurs just below the epidermis. live cells with unevenly thickened cell walls
Features of Sclerenchyma
Provides rigid support. Dead cells with thick tough, lignin-impregnated secondary walls
A horticulturist girdles a tree by removing a ring of its bark and phloem. The tree will ultimately die because it cannot
transport dissolved sugars.
