Plants Overview

Honors Biology Mrs. Mawhiney

Fig. 29-7

Origin of land plants (about 475 mya)1

2

3

1

2

3

Origin of vascular plants (about 420 mya)

Origin of extant seed plants (about 305 mya)

ANCES-TRALGREENALGA

Liverworts

Hornworts

Mosses

Lycophytes (club mosses,spike mosses, quillworts)

Pterophytes (ferns,horsetails, whisk ferns)

Gymnosperms

Angiosperms

Seed plantsSeedlessvascularplants

Nonvascular

plants(bryophytes)

Land plants

Vascular plants

Millions of years ago (mya)500 450 400 350 300 50 0

Seeds

• Seeds changed the course of plant evolution, enabling their bearers to become the dominant producers in most terrestrial ecosystems

• A seed consists of an embryo and nutrients surrounded by a protective coat

Concept 30.2: Gymnosperms bear “naked” seeds, typically on cones

• The gymnosperms have “naked” seeds not enclosed by ovaries and consist of four phyla:– Cycadophyta (cycads)– Gingkophyta (one living species: Ginkgo biloba)– Gnetophyta (three genera: Gnetum, Ephedra,

Welwitschia) – Coniferophyta (conifers, such as pine, fir, and

redwood)

Phylum Cycadophyta

• Individuals have large cones and palmlike leaves

• These thrived during the Mesozoic, but relatively few species exist today

Fig. 30-5a

Cycas revoluta

Phylum Coniferophyta

• This phylum is by far the largest of the gymnosperm phyla

• Most conifers are evergreens and can carry out photosynthesis year round

Fig. 30-5k

Sequoia

Angiosperms

• Angiosperms are seed plants with reproductive structures called flowers and fruits

• They are the most widespread and diverse of all plants

Nonvascular plants (bryophytes)

Seedless vascular plants

Gymnosperms

Angiosperms

Fig. 30-7

Carpel

Ovule

Sepal

Petal

Stigma

Style

Ovary

Stamen Anther

Filament

Video: Flower Blooming (time lapse)Video: Flower Blooming (time lapse)

Fruits

• A fruit typically consists of a mature ovary but can also include other flower parts

• Fruits protect seeds and aid in their dispersal• Mature fruits can be either fleshy or dry

Animation: Fruit DevelopmentAnimation: Fruit Development

Fig. 30-8

Hazelnut

Ruby grapefruitTomato

Nectarine

Milkweed

Fig. 30-13n

MonocotCharacteristics

EudicotCharacteristics

Vascular tissueusually arranged

in ring

Veins usuallyparallel

Vascular tissuescattered

Leafvenation

One cotyledon

Embryos

Two cotyledons

Stems

Veins usuallynetlike

Fig. 30-13o

Roots

Pollen

Root systemusually fibrous(no main root)

Pollen grain withthree openings

Pollen grain withone opening

Floral organsusually in

multiples of three

Flowers

Floral organs usuallyin multiples of

four or five

MonocotCharacteristics

EudicotCharacteristics

Taproot (main root)usually present

Monocots

• More than one-quarter of angiosperm species are monocots

Fig. 30-13e

Orchid

Fig. 30-13f

Eudicots

• More than two-thirds of angiosperm species are eudicots

Fig. 30-13h

California poppy

Fig. 30-13j

Dog rose

The plant body has a hierarchy of organs, tissues, and cells

• There are three basic plant organs:– Roots– Stems– Leaves

Shoot System: Stems and

Leaves• Stems – function

primarily to display the leaves.– Terminal Bud –

area of growth at the top end of stem

– Axillary Buds – area of growth located in the V area between the leaf and the stem (branches)

• Leaves – main photosynthetic organ in plants

Reproductive shoot (flower)Apical bud

NodeInternode

Apicalbud

Shootsystem

Vegetativeshoot

LeafBladePetiole

Axillarybud

Stem

Taproot

Lateralbranchroots

Rootsystem

There are three basic groups of plant tissues:

• Dermal Tissue– Single layer of closely packed cells– Protects plant against water loss and

invasion by pathogens and viruses– Cuticle – waxy layer in leaves

• Vascular Tissue– Xylem and phloem

• Ground Tissue– Any tissue that’s not Dermal or

Vascular tissue– Pith – ground tissue located inside

vascular tissue– Cortex – ground tissue located

outside the vascular tissue

Transport in Xylem and PhloemVascular plants have two types of vascular tissue: xylem

and phloem

• Xylem conducts most of the

water and minerals and includes dead cells called tracheids

• Water-conducting cells are strengthened by lignin and provide structural support

• Increased height was an evolutionary advantage

• Phloem consists of living cells and distributes sugars, amino acids, and other organic products

• Sugar-Conducting Cells of the Phloem• Sieve-tube elements are alive at

functional maturity, though they lack organelles

• Sieve plates are the porous end walls that allow fluid to flow between cells along the sieve tube

• Each sieve-tube element has a companion cell whose nucleus and ribosomes serve both cells

Vegetative PropegationTypes of Veg. Propagation

Description Examples

Bulbs Short Stems Underground

Onions

Runners Horizontal Stems above ground

Strawberries

Tubers Underground Stems

Potatoes

Grafting Cut a stem and attach it to a closely related plant

Seedless Oranges

Tropical Tropismstropism – turning response to a

stimulusPhototropism Refers to how plants respond to

light

Gravitropism Refers to how plants respond to gravity

Thigmotropism Refers to how plants respond to touch (IVY, strangler trees

Auxins Responses are initiated by hormones. Major plant hormones belong to the class AUXINS