Plant Anatomy

Basic plant anatomy 1

A. root– root tip-roots grow

at the tip – root hairs-

increase absorptive surface area

Roots • Roots anchor plant in soil, absorb

minerals & water, & store food– fibrous roots (1)

• mat of thin roots that spread out• monocots

– tap roots (2)• 1 large vertical root • also produces many small lateral,

or secondary roots • dicots

– root hairs (3)• increase absorptive

surface area

2

1

3

Basic plant anatomy 2B. shoot (stem)

– Nodes-where leaves attach• Internodes-space

between nodes

– Buds• Meristems are where

plant shoots grow• terminal or apical buds

at top of stem• axillary buds- at base of

leaf on stem• flower buds-produce

flowers

Basic plant anatomy 3

C. leaves– Cuticle- waterproof layer– Epidermis- covers top &

bottom surface– mesophyll tissue

• Palisade- columnar cells, with choloroplasts just below upper epidermis

• Spongy- irregularly shaped cells with air spaces between them below palisade

– veins (vascular bundles)

Leaves• Function of leaves

– photosynthesis• Traps solar energy• Produces sugars (food)

– gas exchange- occurs through pores called stomates

• Guard cells open or close stomates-depends on water

– Transpiration- water loss through the stomates

Plant adaptations

1. Roots- – Tap root-used for food storage (carrot)

2. Stems-rhizomes (iris) & stolons (strawberry)- used to

make new plants- tubers- (potato) used for storage- Bulbs- (onion) buds used for storage & new

plants

Modified shootsstolons (strawberries) rhizome (ginger)

tuber (potato) bulb (onion)

Plant adaptations3. Leaves• CAM & C4-photosynthesis- chemical

adaptation for plants in hot climates• Enlarged darker leaf-jungle plants-low light• Spines & poisons- defense against

herbivores• Thickened leaf- water storage• Tendrils- climbing plants- attach & support• Bright colors- leaves doing job of petals

succulent leaves

Modified leavestendrils (peas) spines (cacti)

colored leaves (poinsetta)

• Both systems depend on the other– roots need sugars

produced by photosynthetic leaves

– shoots need water & minerals absorbed by roots

Interdependent systems

water &minerals

sugars

Vascular tissues

• Xylem – move water & minerals up from roots – dead at maturity

• only cell walls remain• transpirational pull hauls water up from roots

tracheids

vessel elements

vessel element

dead cells

sieve tube

companion cell

living cells

plasmodesmata sieve plate

Phloem: food-conducting cells • carry sugars & nutrients throughout plant• sieve tube elements – Living at maturity

– Keep cell membrane & cytoplasm– lose their nucleus & organelles– sieve plates — end walls — have pores to

allow flow of food between cells

• companion cells- attached to sieve tubes– run the cell- have nucleus & cell structures

Vascular tissue in stemsdicot

trees & shrubsmonocot

grasses & lilies

collect annual rings

Putting it all together • Obtaining raw materials

– sunlight• leaves = solar collectors

– CO2

• stomates = gas exchange

– H2O• uptake from roots

– nutrients• uptake from roots

Growing Cycles

• Perennials - live several years, and reproduce many times Ex. woody plants

• Annuals - plant that completes its life cycle in one growing season (grows, flowers, reproduces and dies)

• Biennials - take two growing seasons to complete, reproduces in the second growing season

Growing Cycles

• Plants grow only at their tips in regions called MERISTEMS

• PRIMARY GROWTH makes a plant taller at roots and stems

• SECONDARY GROWTH makes a plant wider, or adds woody tissue

How Old Is That Tree?• Tree Rings tell age of a tree,

each ring for one growing season.This tree is 4 yrs old. – Spring wood- lighter colored,

larger tubes– Darker colored, narrower

tubes

• VASCULAR CAMBIUM: makes xylem and phloem and forms the annual rings

Comparison of Monocots & Dicots

Monocots & dicots• Angiosperm are divide into 2 classes

– dicots (eudicot)• 2 cotyledons (seed leaves)• leaves with network of veins• woody plants, trees, shrubs, beans

– monocots• 1 cotyledon• leaves with parallel veins• grasses, palms, lilies

Simple Tissues – consisting of one cell type

• Parenchyma – thin walled & alive at maturity; cells take different shapes. (storage, can change into other cells)

• Collenchyma – thick walled & alive at maturity (support)

• Sclerenchyma – thick walled and dead at maturity (support)– Sclerids or stone cells – cells that are as

long as they are wide, very heavy cell walls– Fibers – cells longer than they are wide

• Epidermis – alive at maturity– Trichomes – hairs on epidermis– Root Hairs – tubular extensions of

epidermal cells