Chapters 22, 23, and 24

� Chapter 22 – Intro to Plants� Classification

� Background Information

� Chapter 23 – Plant Structure and Function� Specialized Tissues

� Plant Organs (Roots, Stems and Leaves)

� Transport in Plants

� Chapter 24 – Plant Reproduction and Response� Reproduction in Flowering Plants

� Plant Responses (Hormones and Tropisms)

� Eukaryotic� Cell walls made of cellulose� Most are autotrophic

� Some are parasitic or saprobes

� Carry out photosynthesis using chlorophyll� Many (not all) contain specialized organs (roots, stems,

leaves)� Includes:

� Green Algae (Formerly categorized as a protist)� Mosses� Ferns� Conifers� Flowering Plants

� Earliest plants were aquatic, movement to land had benefits, but also challenges

Benefits: Challenges:Less competition Dessication

Empty niche Fertilization

� In the end, all plants have basic needs:� Sunlight

� Gas Exchange

� Water and Minerals

� Appeared approximately 550 million years ago

� Mostly aquatic, found in fresh and salt water and moist land areas

� Do not contain specialized tissues

� Examples: Clamydomonas, Volvox, Spirogyra

� Contain specialized reproductive organs enclosed by other, nonreproductive, cells

� Higher degree of specialization than algae, but still lacking true roots, stems and leaves� Must stay low to the ground (no water transport

system)� Must stay near bodies of water (flagellated sperm cells)

� First plants to move onto land, anchored by tough rhizoids, increasing nutrient absorption

� Examples: mosses, liverworts, hornworts

� Evolved approximately 420 million years ago

� Development of tracheids (hollow cells strengthened by lignin) = vascular tissue� Xylem – carries water and nutrients up from the roots

to stems and leaves

� Phloem – carries products of photosynthesis down to roots and stems

� Includes all seeded plants and some seedless plants (ferns, club mosses, horsetails)

� Seed – plant embryo and food supply � First seed plant appeared approximately 360 million

years ago� Allows plants to become completely terrestrial

� Two types of seeded plants� Gymnosperms� Angiosperms

� Pollen Grain – male gametophyte which carries sperm to female reproductive structure

� After fertilization, the embryo is surrounded and protected by a seed coat until conditions are good

� “Naked seed”

� Examples: conifers, ginkgoes, conifers (pine trees)

� Two cones produced:� Pollen cone –

contains pollen grains (pollen grains are male gametophyte)

� Seed cones – produce female gametophytes

� Evolved approximately 135 million years ago

� “Enclosed seeds”� Contain unique reproductive organs � Flowers contain and protect ovaries, which will eventually

develop into fruits (ripened ovaries) which enclose and protect seeds

� Advantages of Flowers and Fruits:� Flowers attract pollinators (insects and birds) which are more

efficient than wind� Sweet taste and smells of fruits attract organism to eat; seeds are

dispersed far away in fecal matter

THINK ABOUT

THAT NEXT

TIME YOU BITE

INTO AN APPLE

����

� Other ways to classify� Monocots – Single cotyledon (seed leaf); includes many

clades

� Dicots – Double cotyledon

� Can also be classified as annuals, biennials, perennials

Kingdom Plantae

Division Bryophyta•No true roots, stems, or leaves•Nonvascular•Transport water by osmosis•Anchor by rhizoids •Ex – mosses, liverworts, hornworts

Division Tracheophyta•True roots, stems, & leaves•Vascular – transport water (xylem) & food (phloem) throughout the plant•Can be divided further into…

Gymnosperms•Naked seeds – not enclosed in tissue• Needle-shaped leaves•Ex – Conifers, ginkos, firs

Angiosperms•Protected seeds – “seed vessel”•Many flower and produce fruits/vegetables•Ex – see below

Seed Producing•Seeds•Ex – see below

Spore Producing•Seedless•Ex - Ferns

Monocot•1 cotyledon (seed leaf)•Parallel venation•Flower parts in 3s•Vascular bundles scattered•Fibrous roots•Ex – corn, grasses, lilies

Dicot•2 cotyledons•Net venation•Flower parts in 4s or 5s•Vascular bundles in rings•Tap root•Ex – beans, maple treesEND OF CHAPTER 22