3.1 plant tissues and the multi cellular plant bodies

root system

portion of plant that is generally underground

shoot system

aerial portion, consists of a vertical stem bearing leaves and, in flowering plants, flowers and fruits that contain seeds.

• the dark, moist soil and

• the illuminated, relatively dry air.

Each plant grows in two different environments, _____ and _____

roots

branch extensively through the soil, forming a network that anchors the plant firmly in place and absorbs water and dissolved minerals from the soil.

leaves

the flattened organs for photosynthesis, are attached regularly on the stem, where they absorb the sunlight and atmospheric CO2 used in photosynthesis to produce carbohydrates.

Herbaceous plants

do not develop persistent woody parts above ground

woody plants

develop persistent woody parts above ground; trees & shrubs

annuals

are herbaceous plants that grow, reproduce, and die in 1 year or season.

biennials

take 2 years to complete their life cycles; During their first season, they produce extra carbohydrates, which they store and use during their second year, when they typically form flowers and reproduce.

Perennials

are woody or herbaceous plants that live for more than 2 years.

• primary cell wall

• A growing cell secretes a thin ____, which stretches and expands as the cell increases in size.

• secondary cell wall

• After the cell stops growing, it sometimes secretes a thick, strong _____, which is deposited inside the primary cell wall

Parenchyma tissue

found throughout the plant body and is the most common type of cell and tissue.

photosynthesis, storage, and secretion.

Parenchyma cells perform a number of important functions for plants, such as

thin

Parenchyma cells have ____ primary cell walls

unevenly thickened

Collenchyma cells have ______ primary cell walls

Collenchyma tissue

a flexible tissue that provides much of the support in soft, nonwoody plant organs.

Sclerenchyma

have both primary cell walls and thick secondary cell walls

Sclerenchyma

A second simple tissue specialized for structural support is

vascular tissue system

embedded in the ground tissue, transports needed materials throughout the plant via two complex tissues: xylem and phloem

xylem

transports water and minerals, one way flow of sap

xylem

thick cell wall made of lignin, cells having no end walls between them

phloem

transports water and food, two way flow of sap

phloem

thin cell wall made of cellulose, cells with end walls and perforations

Sieve-tube elements

the conducting cells of phloem

dermal tissue system

provides a protective covering over plant parts

epidermis

In herbaceous plants, the dermal tissue system is a layer of cells called the

Periderm

a tissue several to many cell layers thick, provides a new protective covering as the epidermis is destroyed.

epidermis

the outermost layer of an herbaceous plant

periderm

replaces epidermis in woody plants

parenchyma cell

living; thin primary cell walls; function as secretion, storage and photosynthesis; found throughout the plant body

collenchyma cell

living; unevenly thickened primary cell walls; function as support; found just under stem epidermis, along leaf veins

sclerenchyma cell

often dead at maturity; thick secondary walls; function as support; found throughout the plant body; common in stems and certain leaves

tracheid

dead at maturity; lacks secondary cell wall at pits; function as conduction of water and minerals and support; found in xylem

vessel element

dead at maturity; end walls have perforations; lacks secondary cell wall at pits; function as conduction of water and minerals and support; found in xylem

sieve tube element

living; end walls are sieve plates; lack nuclei and other organelles at maturity; conduction of dissolved food materials; found in phloem

companion cell

living cytoplasmic connections with sieve tube element; aids sieve tube element; found in phloem

epidermal cells

living; cells fit tightly together; function as protective covering over surface; found in outermost layer of cells

Plant Meristems

composed of cells whose primary function is the formation of new cells

Plant Meristems

meristematic cells

do not differentiate. Instead, they retain the ability to divide by mitosis, a trait that many differentiated cells lose.

Primary growth

an increase in the length of a plant.

Secondary growth

an increase in the girth of a plant.

root cap

protects the root apical meristem

area of cell elongation

where cells enlarge and begin to differentiate

pical meristem

where cells divide and thus increase in number

Primary growth

occurs as a result of the activity of apical meristems, areas at the tips of roots and shoots.

apical meristems

Primary growth takes place at

lateral meristems

Secondary growth takes place at

lateral meristems

areas that extend along the entire lengths of stems and roots, except at the tips.

• vascular cambium

thin layer of cells sandwiched between the wood and bark, produces secondary vascular tissues

• cork cambium

produces periderm

periderm

the outer bark tissues that replace the epidermis in the secondary plant body

protoderm, procambium, ground meristem

3 primary meristems found in the area of elongation give rise to the mature cell types in the are of cell maturation