Introduction to Plants

Classification of plants• Kingdom Plantae

– Phylums• Lycodiophyta (Club Mosses)• Equisetophyta (Horsetails)• Psilotophyta (Wisk Ferns)• Polypodiophyta (Ferns)• Cycadophyta (Cycads)• Ginkgophyta (Ginkoes)• Pinophyta (Conifers)• Gnetophyta (Vessel-bearing Gymnosperms)• Magnoliophyta (Flowering Plants)

Facts…• critical to other life on this planet because they

form the basis of all food webs• Most plants are autotrophic• earliest fossils found have been aged at 3.8

billion years• scientific study of plants, known as botany • identified about 350,000 extant (living) species

of plants – ~258,650 are flowering and ~18,000 bryophytes

What are plants?

• Multi-cellular organisms

• Make own food (photosynthesis)

• Have chloroplasts• Have rigid cell walls

made of cellulose• Found all over the

world

Plants provide:• Food• Oxygen• Medicines• Building materials• Textiles (fibers)• Coloring pigments

Plant Classification

E X : G in ko E X : con ife rs

G ym n osp e rm s"n a ke d s e ed s"

co n es , no flow e rsn e e d le -lik e lea v es

E X : gra s ses E X : o rch ids

M o no c o ts

E X : o a k tree E X : b ro c co li

D ico ts

A n g io sp e rm sflo w erin g p la n ts

la rg es t g ro up

W ith s e e ds

M o sses F e rns L iv e rw o rts H o rs e ta ils

W itho u t se e dsn e ed w a ter to

re p ro d uce ;sp o res

P la n ts

Plants Without Seeds

• Need water to reproduce• Reproduce with spores• Include

–Mosses–Ferns–Horsetails–Bladderworts

Plants with Seeds

• 2 types• Found all over the world

Gymnosperms• Means “naked seed”• Often have cones & needle-like

leaves• Do not have flowers

–Ex: conifers, gingko

Angiosperms

• Flowering plants• Largest group

– Moncots– Dicots

Monocots

Dicots

Evolution• Principal photosynthetic organisms were

microscopic cells floating below the surface of the water, closer to the sun’s rays

• As they multiplied, depleted resources of the open ocean, so colonies could be found nearer to the shores, in order to get minerals and nutrients from runoff

• About 650million years ago, diversity of these organisms abounded on the rocky shores, and some even integrated into multicelluar bodies

Evolution

• These new multicelluar photosynthetic forms developed a cell wall due to the rough waters of the rocky coastline

• As size increased, they developed internal structures that linked the photosynthesizing parts to the non-photosynthesizing parts

Evolution to land..

• Oxygen & carbon dioxide not as abundant in the water, as it is not as free circulating as it is on land

• Critical factor to adapting to land is water resources

• Development of root systems to be able to keep plant stable on land and to seek out water resources without moving

RootsWhat do they do for the plant???

Are you Rooted?

• Roots help to keep plants in place. • They spread out into the soil and

“attached” themselves to the particles of the soil.

• Why do they reach and probe?– To find nutrients and water, thus in the end

the plant gets anchored into the soil.

Root Hairs• Water in the soil is

taken up by root hairs and then passes from cell to cell to the xylem.

Types of Roots

• Generally grasses have this type of root

• Many roots extend into the soil from base of plant

• One or more large roots extending into the soil

• Smaller roots branch off

Fibrous Roots Tap Roots

Types of Roots• Shallow roots

– Desert roots– Quickly growing

plants

• Deep underground roots– Areas with little

rainfall

• Deep and Shallow Roots– Takes

advantage of underground water sources and occasional showers.

Root Growth

• Amount of moisture in the soil• Type of soil• How quickly the plants grow and go to

seed• Type of rainfall in that area• Type of plant – prop roots are used to

help support the plant

What does it depend on?

Lastly…• Roots are used as food storage for

plants. They store sugars and starches to help plants over winter.

• Sugar storage in roots also help to send up new shoots each spring, and to regenerate stems and leaves that were eaten or burned.

• Radishes, carrots, turnips – store large amounts of food in the form of starch in their roots. We eat these roots as a source of energy.

Plant Functions

What do stems & leaves do for a plant???

Stems

Transport of Materials

• Phloem (2)– Carries sugars (food)

up & down in plant

• Xylem (1)– Carries water &

mineral up from roots to all parts of plants

Leaves

Photosynthesis

• Leaves collect sunlight, water and carbon dioxide to make sugar (food) for the plant

• The chemical equation for this process is

6 H2O + 6 CO2 C6H12O6 + 6 O2

sugar

Sun en

ergy

Respiration• Leaves break down

sugars to get energy• This process releases

excess water as waste

• The chemical equation is

• C6H12O6 + 6 O2 energy + 6 H2O + 6 CO2

Ener

gy re

leas

ed

To h

elp

plan

t gro

w

sugar

Transpiration

• Taking in CO2 and releasing O2 and H2O as waste products after respiration