plant tissues

Meristematic tissues

tissues with actively dividing cells that produce more cells

Apical meristems

located at root and shoot tips; increase plant length

Primary meristems

tissues produced by apical meristems: protoderm, ground meristem, procambium

Protoderm

primary meristem that develops into epidermis

Ground meristem

primary meristem that develops into ground tissues

Procambium

primary meristem that develops into vascular tissues (xylem & phloem)

Lateral meristems (cambia)

found on the sides of roots and stems; increase girth or diameter

Vascular cambium

lateral meristem producing xylem and phloem

Cork cambium

lateral meristem producing cork

Intercalary meristems

found at nodes of stems; increase stem length; short-lived, later becoming permanent tissues

Permanent tissues

tissues derived from meristems that matured and specialized for specific functions

Simple permanent tissues

composed of only one type of cell, uniform in structure and function

Parenchyma

most abundant tissue; thin-walled, large vacuoles, variable shapes; functions in food and waste storage

Aerenchyma

parenchyma with large connected air spaces for buoyancy

Chlorenchyma

parenchyma with chloroplasts, specialized for photosynthesis

Collenchyma

elongated cells with unevenly thickened cell walls beneath epidermis; flexible support tissue

Sclerenchyma

cells with thick, lignified walls; dead at maturity; provide strength and support

Sclereids (stone cells)

short, irregular sclerenchyma cells scattered in tissues; make fruits gritty (e.g., pear, chico)

Fibers

long, narrow sclerenchyma cells with central lumen; provide tensile support

Epidermis

outermost single layer of cells covering young plant organs

Cutin

fatty substance secreted by epidermis forming cuticle

Cuticle

protective, water-resistant layer covering epidermis

Trichomes

hair-like outgrowths of epidermis; may be protective or glandular

Guard cells

specialized epidermal cells with chloroplasts, control stomata opening and closing

Cork

protective tissue replacing epidermis in older stems and roots; dead at maturity; cells contain suberin

Suberin

waxy substance in cork cells, makes them impermeable to water and gases

Secretory tissues

specialized cells secreting plant hormones or waste products

Complex permanent tissues

composed of different types of cells working together for transport

Xylem

complex tissue that transports water and dissolved minerals from roots upward

Xylem fibers

sclerenchyma-like cells that provide support

Xylem parenchyma

parenchyma cells in xylem, store food

Vessels

long tubular structures formed by open-ended cells, wide for efficient water transport

Tracheids

elongated cells with tapering ends, dead at maturity, conduct water

Tracheary elements

collective term for tracheids and vessels

Spiral thickening

Types of tracheary element secondary wall thickening: helical bands of thickening

Scalariform thickening

Types of tracheary element secondary wall thickening: ladder-like pattern

Pitted thickening

Types of tracheary element secondary wall thickening: presence of pits (round depressions) on walls

Reticulate thickening

Types of tracheary element secondary wall thickening: net-like pattern

Annular thickening

Types of tracheary element secondary wall thickening: ring-shaped thickenings

Phloem

complex tissue that transports organic food (sugars) from leaves to other plant parts

Sieve tube elements

elongated living cells joined end-to-end with sieve plates; transport food but lack nuclei

Companion cells

nucleated parenchyma cells associated with sieve tubes, support their function

Phloem fibers

sclerenchyma-like cells in phloem, provide support

Phloem parenchyma

parenchyma-like cells in phloem, store food

Sieve plates

perforated end walls between sieve tube elements, allow movement of food substances