Cells and tissues in botany

amyloplast

A plastid that serves in starch storage; a type of leucoplast

chitin

N-containing polymer chain making up the cell wall microfibrils in most fungi

chromoplast

A plastid that has pigments producing red, yellow, and other colors found in flowers, fruits, and other structures

cristae

The infoldings or inward projections of the inner membrane of the mitochondrion, which are studded with proteins and increase the surface area for chemical reactions to occur during cellular respiration

cutin

A waxy polymer that composes the outer cuticle coating parts exposed to air in most plants

elaioplast

A plastid that serves as storage for oil; a type of leucoplast

etioplast

An immature chloroplast or chloroplast deprived of light, lacks active chlorophyll pigment

flaccid

Wilted/limp due to low fluid content resulting in low turgor pressure that occurs when a plant is deprived of water

leucoplast

A colorless plastid found within the cells of roots, underground stems, and storage organs for the storage of starch, oil, or proteins

lignin

A strengthening carbohydrate polymer/polysaccharide found within secondary cell walls of trachied and vessel element cells of wood as well as fibers and sclereids occurring throughout various tissues and structures

middle lamella

A pectin-rich intercellular material that adheres the adjacent cells together and forms first after cell division

pectin

A carbohydrate polymer/polysaccharide that provides structural support in primary cell walls and the middle lamella

peptidoglycan

A glycan sugar complexed with amino acids that provides structural support to most bacterial cell walls; this is much thicker in Gram positive than in Gram negative bacteria; also known as murein

photosynthesis

The cellular fixation of inorganic carbon dioxide into organic carbohydrate utilizing radiant energy

plant

Any of the eukaryotic multicellular organisms of the biological kingdom Plantae characterized by being photosynthetic and having a rigid cell wall containing cellulose

plasmodesmata

Cytoplasm strands that pass through cell walls connecting the protoplasts of adjacent cells; this allows for the passage of materials directly between cells

primary cell wall

The layer of the plant cell wall that forms first in elongating cells prior maturation and in some cells the subsequent deposition of the secondary cell wall; it is characterized by being a thin, flexible and extensible layer of the cell wall composed of cellulose, pectin and hemicellulose

proteinoplast

A plastid that serves as storage for proteins; a type of leucoplast

respiration

The cellular oxidation of organic matter to yield ATP

secondary cell wall

The layer of the plant cell wall that forms between the primary cell wall and the plasma membrane and is characterized by being a thick layer rich in lignin that strengthens the wall

statolith

Amyloplast inclusions with starch grains in the cytoplasm that trigger response to gravity by the root camp, providing a geotrophic response

suberin

Waxy polymer found within the cell walls of the endodermis (producing the Casparian strip) and the cork that functions in waterproofing and prevention of decay

tonoplast

A membrane bounding the vacuole

pluripotency

The capacity exhibited by certain types of isolated differentiated plant cells to develop into any cell type

turgid

Swollen cell due to a high fluid content increasing turgor pressure that occurs when a plant has optimal water content

turgidity

The state of being swollen (turgid) due to a high fluid content within a cell that allows for overall structural rigidity in plants without a need for a skeletal structure and allows for plant movement

turgor pressure

Pressure that is exerted by the cellular fluid (e.g., water in the vacuole) against the cell wall; also referred to as hydrostatic pressure

vacuole

A membrane-bound sac organelle comprising the majority volume in a cell whose function is to regulate turgor pressure as well as intracellular secretion, excretion, storage, and digestion

bark

All of the collective tissues outside the vascular cambium in the stems and roots of plants exhbiting secondary growth; includes both vascular inner bark (secondary phloem) and dermal outer bark (periderm)

collenchyma

Tissue composed of elongated cells, with thick, unevenly thickened, nonlignified primary cell walls often used for flexible structural support

companion cell

A specialized parenchyma cell associated with an adjacent sieve tube element in the phloem of Angiosperms

cork

Outermost parenchymatous tissue of the periderm that that is dead at maturity and protects the inner plant tissues from fluid loss, injury, pathogens, etc.

cork cambium

Secondary (lateral) dermal meristematic tissue that gives rise to cork and cork parenchyma, with all three of these tissues comprising the secondary dermal tissue periderm

cork parenchyma

Innermost parenchymatous tissue of the periderm produced by cork cambium that is alive at maturity and functions in storage; not present in all barks

cuticle

Continuous layer of cutin secreated by the epidermis that covers the aerial parts of the plant body and primarily prevents water loss but also provides minor mechanical protection

dermal tissue

Tissue that comprises the outer covering of a plant, including the epidermis and periderm (outer bark).

embolism

A condition that results when air (e.g., bubbles) invades vessels causing disruption of normal fluid flow

fiber

A long lignified sclerenchyma cell, typically with simple pits, that functions in structural support

ground tissue

Any tissue not of dermal or vascular origin

guard cell

Pair of specialized, chloroplast-containing epidermal cells surrounding the stomatal pore, forming the stoma and regulating gaseous exchange

inner bark

Produced by the vascular cambium, this secondary phloem transports sucrose

Kranz anatomy

Specialized leaf anatomy in C4 plant with the region of mesphyll tissues distinct from conspicuous photosynthetic bundle sheaths surrounding the vascular bundles

lenticel

A small pore containing loosely-packed cells that allows for gaseous exchange in the periderm; replaces stomata of primary tissues.

mesophyll

Ground tissue of a leaf identified as photosynthetic chlorenchyma; this may be distinguished into regions of spongy mesophyll and palisade mesophyll

outer bark

Protective secondary dermal tissue made up of phellogen, phellem, and phelloderm for waterproofing and forms on wounds to prevent entry of pathogens; replaces the epidermis as the outermost dermal tissue layer

palisade mesophyll

Photosynthetic chlorenchyma tissue made up of elongated cells arranged in closely-packed radial columns functioning primarily in photosynthesis

parenchyma

Tissue typically composed of more or less isodiametric cells with thin, nonlignified cellulose walls; often functions in storage

pericycle

Meristem parenchymatous tissue located inside the root endodermis and is the outermost part of the vascular cylinder (the stele) that in Dicots has the capacity to produce lateral roots

periderm

Protective secondary dermal tissue made up of phellogen, phellem, and phelloderm for waterproofing and forms on wounds to prevent entry of pathogens; replaces the epidermis as the outer tissue layer

phellem

The outermost parenchymatous tissue of the periderm that that is dead at maturity and protects the inner plant tissues from fluid loss, injury, pathogens, etc.; synonym of cork

phelloderm

Innermost parenchymatous tissue of the periderm produced by phellogen that is alive at maturity and functions in storage; not present in all barks; synonym of cork parenchyma

phellogen

Secondary dermal meristematic tissue that gives rise to phellem and phelloderm, with all three of these tissues comprising periderm; synonym of cork cambium

primary meristem

Meristem of indeterminate cells that never lost the ability to divide, yielding primary growth, and gives rise to primary tissues, typically resulting in the lengthening of the plant

primary thickening meristem

Meristem found in some Monocotyledons, such as palms, below the leaf primordia at the apex that increases the width (girth) of the stem

primary tissue

Tissue formed from a primary meristem that generally contributes to the lengthening of the organ

root hair

A trichome (a specialized epidermal cell) on the the root surface that increases the root's surface area allowing for greater absorption

sap

The liquid, consisting of mineral salts or sugar dissolved in water, that is found in xylem or phloem, respectively; the term is also used of the fluid in the cell vacuole (vacuolar sap)

sclereid

A short, cuboidal sclerenchyma cell that is lignified to provide structural support for the cell

sclerenchyma

Structural tissue composed of sclereids and/or fibers that have thick lignified cell walls; usually dead at maturity

secondary meristem

Meristem of indeterminate cells that lost the ability to divide then regained it, yielding secondary growth, giveing rise to secondary tissues and typically resulting in increasing the girth (width) of the plant; also known as lateral meristems

secondary tissue

Tissue formed from a secondary meristem that usually contributes to the widening or girth of a plant

sieve-tube member/element

A living phloem cell present in Angiosperms identified by the presence of a sieve plate (perforated, nonlignified area of secondary cell wall) and degenerated organelles

spongy mesophyll

The part of leaf mesophyll that is composed of cells that are irregularly shaped and lobed and are loosely packed with large interceullular spaces; this facilitates gaseous exchange between the atmosphere and the mesophyll

tracheary elements

A water conducting cell in the xlyem that includes tracheids and vessel elements

tracheid

A tracheary cell in the xylem of most plants, possessing a lignified secondary cell wall, and usually lacking a living protoplast (it is dead at maturity); this is distinguishable from vessel elements by their lack of perforation plates.

trichome

A specialized epidermal cell characterized by an outgrowth that extremely varied in appearance and function

vascular cambium

A secondary (lateral) vascular meristem that gives rise to secondary xylem (wood) and secondary phloem (inner bark)

vascular tissue

Xylem and phloem tissues that aid in the transport of substances, such as water and nutrients, and sugar, respectively, throughout a plant

vessel member/element

A tracheary cell that joined end to end that forms vessels in the xlyem of some ferns, most Angiosperms, and the Gnetales. They are characterized by the presence of a perforation plate, a lignified secondary cell wall, and are dead at maturity

wood

Secondary xylem with the primary function of upward transport of water and nutrients

woody

Of orcontaining wood; also often denotes plants with secondary bark as well