Plant Structure and Function

Specialized Tissues in PlantsPlant Organs: Roots, Stems, and LeavesRoots

Anchor the plant and absorb nutrients and water Mutualistic relationship with mycorrhizae and

rhizobacteria

Transport Nutrients to the plant

Store Food

Specialized Tissues in PlantsStems

Support the plant

Transport water and nutrients

Protect against predators and disease

Specialized Tissues in PlantsLeaves

Conduct photosynthesis

Increased SA:V with leaf size

Protect against water loss Waxy cuticle Stomata and Guard Cells

Specialized Tissues in PlantsPlant Tissues: Dermal, Vascular, and Ground Tissue

Specialized Tissues in Plants

Dermal TissueCovers the plant

Epidermis (epi = upon) – single layer of cells on the outside of the plant

Cuticle – layer of wax that covers the epidermis and prevents water loss (polarity?)

Trichomes – tiny hairlike projections for protection Bark – covers the epidermis in woody plants Root hair cells are found on the epidermis of roots

to help absorb water (SA:V)

Specialized Tissues in PlantsVascular Tissue

Vessels that transport water and nutrients Plant “bloodstream”

Xylem – carries water Phloem – carries nutrients

Specialized Tissues in PlantsGround Tissue

Produces and Stores food (sugars) Composes most of the edible portions of plants

Contributes to the physical support of the plant

Plant Growth and MeristemsMeristems – regions of

specialized plant cells in which mitosis produces new cells ready for differentiationThe undifferentiated cells

produced are much like the stem cells of animals

Located in parts of plants that undergo rapid growth

Allow even the oldest trees to produce new leaves and new reproductive organs each year

Apical Meristem – located at the end (apex) of a root or stem.Leads to increase in root

or stem lengthOnce produced, the new

cells differentiate into new dermal, vascular, and ground tissue

Floral MeristemsProduce the tissues of

flowers Includes the plant’s

reproductive organs as well as the colorful petals that surround them

TropismThe (growth or turning) movement of a plant in response to

an environmental stimulus Includes –

Phototropism Gravitropism Thigmotropism

TaxisThe movement (or migration) of an animal in response to an

environmental stimulus Includes –

Hydrotaxis Thermotaxis Magnetotaxis Phototaxis

PhototropismThe growth or movement of a plant in response to light

Positive phototropism is expressed when a plant moves toward the light (stems and leaves)

Negative phototropism is expressed when a plant moves away from the light (roots)

Gravitropism (geotropism)The growth or movement of a plant in response to gravity

Positive gravitropism is expressed when a plant moves with the pull of gravity (roots)

Negative gravitropism is expressed when a plant moves against the pull of gravity (stems and leaves)

ThigmotropismThe growth or movement of a plant in response to touch

Positive thigmotropism is expressed when a plant moves towards touch (venus fly trap and vines) http://www.youtube.com/watch?v=hGCg5bhV1X4

Negative thigmotropism is expressed when a plant moves away from touch (stems and leaves) http://www.youtube.com/watch?v=BLTcVNyOhUc