PLANT STRUCTURE AND FUNCTION

D Jones

Plant Cell Types parenchyma

– metabolism– storage– contain plastids that store

store starch – support with growth

sclerenchyma– support without growth– two forms

fibers (flax and hemp) sclereids (nutshells)

Xylem water conducting

dead at maturity– tracheids

• long, thin, tapered ends– vessel elements

• wider, shorter, thin walled, less tapered

Phloem food conducting live at maturity

– sieve-tube members• Have sieve plates

– companion cells

Tissue Systems dermal

– epidermis tightly packed cells cover and protect

vascular– xylem & phloem

transport & support

ground– mostly parenchyma

photosynthesis, storage & support

– collenchyma– sclerenchyma

Plant Systems roots Stems leaves flowers & seeds

Functions of Roots absorb water and nutrients anchor plants conduct water and nutrients store food

Types of Roots fibrous roots

– mat of thread-like roots– just below soil surface– found in monocots

tap roots– one long root– deep into soil– found in dicots

Root Cross Section

Monocot

Dicot

epidermiscortex

endodermis xylem

pericycle

xylem

phloem

cortex

Tissue Characteristics & Functions

Tissue Characteristics Function

Cortex Cellular spaces for aeration

Stores starch

endodermis Tightly packed produce suberin(creates water barrier called casparian strip

Control movement of water into center of root and prevent outward movement

Root hairs give surface area for absorption

Functions of Stems transport materials support storage

Types of Stems Herbaceous

– in annuals– green (photosynthesize)– pliable

Woody– in perennials– have bark– inflexible

Stem Cross Sectionsmonocot

dicot

phloem

xylem

vessel element (xylem)air spacephloem

Tissue functions epidermis – produces waxy cuticle of

cutin to protect from water loss cortex – ground tissue containing

chloroplasts vascular cylinder – xylem, phloem and

pith

Woody Stemperiderm

cork cambium

cortexphloem

xylem

vascular cambium

pith

Tissue functions

vascular cambium – produces new xylem and phloem

periderm (bark or cork)– protects from water loss

cork cambium – produces periderm Sapwood – outermost water-conducting

xylem Heartwood – innermost supporting xylem

Leaf Functions photosynthesis – food production

Functions of Leaves photosynthesis

Types of Leaves Simple

compound– Pinnate

– palmate

Leaf Cross Section

Tissue Functions epidermis – covered by waxy cuticle of cutin

that limits water loss palisade mesophyll – specialized for

photosynthesis – tightly packed spongy mesophyll – air spaces allow gas

exchange guard cells – open and close stomata to

allow gas exchange and limit water loss vascular bundles – transport of water and

food

Stomata Functioning guard cells have thicker cell walls near

the stomata when water moves into guard cells

they expand and open when water moves out the guard cells

close

Factors that Affect Stomata

temperature – stomata close limiting water loss when the temperature is high

CO2 concentration – stomata open when CO2 is low allowing photosynthesis

day/night – stomata open during the day and close at night

Flowers and Seeds reproduction

Flower structure

Functions of Flower Parts petals – attract birds and insects sepals – protect flower buds stamen – male structures that produce

pollen pistil – female structures tha produce

ovules

Seeds

Tissue Functions seed coat - protection Endosperm - storage Cotyledon - storage epicotyl – becomes shoot tip hypocotyl – becomes shoot radical – becomes root

Monocot /Dicot Comparison