REPRODUCTION IN SEED PLANTS – CH.24

COMPLETE (PERFECT) FLOWERS

• COMPLETE FLOWERS HAVE 4 TYPICAL FLOWER PARTS: STAMENS, PISTILS, SEPALS, AND PETALS.

• THE BASIC STRUCTURE OF A TYPICAL FLOWER IS MADE UP OF FOUR CONCENTRIC WHORLS (CIRCLES) IN ORDER FROM OUTER PART TO INNER PART:

1. CALYX – OUTERMOST WHORL – MADE UP OF ALL OF THE SEPALS

2. COROLLA – NEXT WHORL – MADE UP OF ALL OF THE PETALS

3. ANDROECIUM – NEXT WHORL – MADE UP OF ALL OF THE STAMENS

4. GYNOECIUM – INNERMOST WHORL – MADE UP OF ONE OR MORE PISTILS

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Section 24-1

 The Structure of a Flower

ESSENTIAL FLOWER PARTS (REQUIRED FOR REPRODUCTION)

• PERFECT FLOWERS: BOTH KINDS OF REPRO PARTS (BISEXUAL); MAY HAVE SELF OR CROSS POLLINATION **MOST FLOWERS (EG. ROSES, GLADIOLUS, BUTTERCUPS)

• IMPERFECT FLOWERS: ONLY ONE KIND OF REPRO PART (UNISEXUAL); CAN ONLY HAVE CROSS POLLINATION1. STAMINATE FLOWERS: MALE – STAMENS ONLY (MAKE POLLEN) *TASSEL OF CORN PLANT2. PISTILLATE FLOWERS: FEMALE – ONLY HAVE PISTILS (MAKE EGGS) *SILK PART OF CORN PLANT

MONOECIOUS PLANTS: IMPERFECT FLOWERS- MALE & FEMALE FLOWERS ON THE SAME PLANT (EG. CORN, SQUASH, CUCUMBER, PUMPKIN, WALNUTS)

DIOECIOUS PLANTS: IMPERFECT FLOWERS-MALE & FEMALE FLOWERS ON TWO DIFFERENT PLANTS (EG. DATES, PLUMS, ASH, MAPLES, SPINACH)

NONESSENTIAL FLOWER PARTS (NOT INVOLVED IN REPRODUCTION)

• SEPALS – OUTERMOST WHORL OF LEAF-LIKE PARTS, USUALLY SMALL & GREEN. ALL OF THE SEPALS MAKE UP THE CALYX

• PETALS – NEXT WHORL OF LEAF-LIKE PARTS, USUALLY LARGE, COLORFUL, AND FRAGRANT. ALL OF THE PETALS ON ONE FLOWER MAKE UP THE COROLLA*IN SOME FLOWERS THE SEPALS LOOK EXACTLY LIKE THE PETALS IN SIZE, SHAPE, & COLOR (EG. LILY), BUT THE OUTERMOST WHORL (CALYX) IS STILL MADE UP OF ALL OF SEPALS*IN SOME ATYPICAL FLOWERS THE SEPALS AND PETALS DO NOT LOOK “TYPICAL” – NOT COLORFUL OR LARGE AT ALL (EG. WEEDS LIKE JOHNSON GRASS), BUT THESE TWO PARTS STILL MAKE UP THE OUTER 2 WHORLS (CALYX & COROLLA)

REPRODUCTIVE PARTS – MALE (ESSENTIAL PARTS)

STAMEN – MALE REPRODUCTIVE ORGAN. MADE OF:1. ANTHER: ENLARGED TIP THAT PRODUCES POLLEN – EACH POLLEN GRAIN HAS 2 HAPLOID (N) NUCLEI (1 IS THE TUBE NUCLEUS, OTHER THE GERM NUCLEUS)2. FILAMENT:STALK-LIKE PART THAT SUPPORTS THE ANTHER

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REPRODUCTIVE PARTS – FEMALE (ESSENTIAL PARTS)

PISTIL – FEMALE REPRODUCTIVE ORGAN (ALSO CALLED CARPEL) MADE OF:

1. STIGMA: STICKY PART AT TOP – MAY HAVE ONE TO SEVERAL DISTINCT LOBES – CONTAINS MOISTURE & SUGARS NEEDED FOR POLLEN GRAIN GERMINATION AFTER POLLINATION

2. STYLE: STALK-LIKE PART THAT SUPPORTS THE STIGMA- POLLEN TUBE WILL GO DOWN STYLE TO OVARY. AT THE TOP PART OF THE STYLE, MITOSIS OF GERM NUCLEUS WILL FORM 2 SPERM NUCLEI & THESE WILL BE CARRIED TO THE EGG BY THE POLLEN TUBE. THE POLLEN GRAIN AND POLLEN TUBE COMPLETELY ELIMINATE THE NEED FOR H20 FOR SWIMMING SPERM THAT LIMITED MOSS & FERN REPRO.

3. OVARY: ENLARGED BASE AT BOTTOM OF PISTILOVULE (EMBRYO SAC): FEMALE GAMETOPHYTE – WILL PRODUCE 8 HAPLOID NUCLEI WHICH POSITION THEMSELVES AS ANTIPODALS/POLAR NUCLEI/SYNERGIDS/EGG. THE EGG & POLAR NUCLEI WILL BE INVOLVED IN DOUBLE FERTILIZATION FORMING THE ZYGOTE (EMBRYO) & THE ENDOSPERM (STORED FOOD) INSIDE THE DEVELOPING SEEDPERICARP: OUTER WALL OF OVARY THAT WILL ENLARGE WHEN MATURE, FORMING FRUITCARPELS: SECTIONS W/IN THE OVARY WHERE DEVELOPING SEEDS WILL BE FOUND. THE # OF CARPELS OFTEN EQUALS THE # OF LOBES FOUND MAKING UP THE STIGMA

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FLOWER CLASSIFICATION

• MONOCOTS – FLOWER PARTS IN 3’S OR MULTIPLES OF 3 (LILY)

• DICOTS – FLOWER PARTS IN 4’S OR 5’S OR MULTIPLES OF 4 OR 5 (BUTTERCUPS OR ROSES)

ANGIOSPERM LIFE CYCLE

• Click the image to play the video segment.

Video

Life Cycle of Angiosperms

MICROSPOROGENESIS (IN ANTHER – POLLEN FORMATION)

1. MICROSPORE (POLLEN) MOTHER CELL (2n) UNDERGOES 1 MEIOTIC DIVISION TO PRODUCE 4 MICROSPORES (n)

2. 4 MICROSPORES (n) UNDERGO 1 MITOTIC DIVISION TO PRODUCE 4 HAPLOID POLLEN GRAINS WITH 2 NUCLEI EACH (GENERATIVE NUCLEUS & TUBE NUCLEUS).

3. POLLEN GRAIN (IN ANTHER AWAITING ITS RUPTURE) IS THE MALE GAMETOPHYTE!!!

GERMINATING LILY POLLEN GRAIN

MEGASPOROGENESIS (IN OVARY) EMBRYO SAC FORMATION

1.MEGASPORE MOTHER CELL (2n) UNDERGOES 1 MEIOTIC DIVISION TO PRODUCE 1 HAPLOID CELL (OTHER 3 DISINTEGRATE)

2.1 MEGASPORE UNDERGOES 3 MITOTIC DIVISIONS TO PRODUCE 1 EMBRYO SAC THAT HAS 7 CELLS IN IT: 3 ANTIPODALS (n), 2 SYNERGIDS (n), 1 EGG CELL (n) & 1 POLAR NUCLEI CELL (2n).

3. EMBRYO SAC IS THE FEMALE GAMETOPHYTE!

*BOTH THE POLLEN GRAIN AND THE EMBRYO SAC ARE:1. MICROSCOPIC2. INCONSPICUOUS3. SHORT-LIVED4. DEPENDENT

EMBRYO SAC

POLLINATION TO SPOROPHYTE

POLLINATION FOLLOWED BY FERTILIZATION

1.POLLEN GRAIN LANDS ON THE STIGMA & GERMINATES, FORMING A POLLEN TUBE (FROM TUBE NUCLEUS) THAT CARRIES SPERM NUCLEI THROUGH THE STYLE INTO THE OVARY

2. WHILE IN THE POLLEN TUBE, THE SPERM NUCLEUS (n) DIVIDES (MITOSIS) TO PRODUCE 2 SPERM NUCLEI (n)

FERTILIZATION1. TUBE NUCLEUS

DISINTEGRATES ONCE POLLEN TUBE PUNCTURES THE OVULE (IN OVARY)

2. FERTILIZATION! SPERM (n) + EGG(n) = EMBRYO (2n)

3. SPERM (n) + 2 POLAR NUCLEI CELLS(n) = ENDOSPERM (3n)

4. SYNERGIDS & ANTIPODALS DISINTEGRATE

DOUBLE FERTILIZATION(CHARACTERISIC OF

ANGIOSPERMS)

1. SPERM + EGG = EMBRYO(2n)

2. SPERM + 2 POLAR NUCLEI CELLS = ENDOSPERM (3n)

SEED/FRUIT FORMATION

• OVULE WALL HARDENS TO FORM SEED COAT – SURROUND/PROTECT EMBRYO & ENDOSPERM

• OVARY WALL GETS THICKER TO FORM FRUIT WHICH ENCLOSES SEEDS

SEEDS IN A POD

SEEDS

3 PARTS1. EMBRYO – YOUNG

PLANT2. ENDOSPERM –

STORED FOOD3. SEED COAT -

PROTECTION

REPRODUCTION IN HIGHER PLANTS

GYMNOSPERMS (CONIFERS)

• HAVE CONES• DRY SEEDS ARE EXPOSED ON

SCALES OF CONES (NOT ENCLOSED)

• EG. PINE, SPRUCE, FIR, CEDAR

ANGIOSPERMS (FLOWERING PLANTS)

• PRODUCE FRUIT• SEEDS ENCLOSED (PROTECTED)

BY FRUIT• EG. ROSE, LILY, TULIP, DAISY,

SUNFLOWERVEGETABLES: TOMATOES, BEANS, SQUASH, WATERMELONTREES: MAGNOLIA, FRUITUNUSUAL FLOWERING PLANTS (ATYPICAL FLOWER PARTS)TREES: PECAN, OAKVEGETABLES: CORNGRASSES: CEREALS, GRAINS, WEEDS

STEPS IN PLANT REPRODUCTION

1. FORMATION OF EGG & POLLEN (SPERM)2. POLLINATION (TRANSFER)3. POLLEN TUBE FORMATION (GROWING

DOWN STYLE)4. FERTILIZATION/FUSION (OVARY)5. FRUIT FORMATION (BASE OF FLOWER)6. SEED DEVELOPMENT (INSIDE FRUIT)7. SEED DISPERSAL (SPREADING)8. SEED GERMINATION (SPROUTING)9. GROWTH OF PLANT10.FORMATION OF FLOWER/CONE (MALE &

FEMALE GAMETOPHYTES)

REPRODUCTION: BASIC PROPERTY OF ALL LIFE, MAINTAINS THE SPECIES – 2

METHODS:ASEXUAL

OFFSPRING FORMED FROM 1 PARENT – NO VARIATION, OFFSPRING IDENTICAL TO PARENT-ONLY SOURCE OF VARIATION: MUTATION

EXAMPLES: 1. MITOSIS- “COPIES” OF PARENT CELL2. SPORES – CELL ENCLOSED IN

PROTECTIVE WALL, UNDER FAVORABLE CONDITIONS WILL RUPTURE, GROW, FORM NEW ORGANISM

3. VEGETATIVE PROPAGATION- PLANT REPRO WITHOUT SEEDS – PART OF PARENT CAN FORM OFFSPRINGLEAVES: AFRICAN VIOLETS, CHICKENS & HENS, BEGONIASTEMS: ROSES, STRAWBERRIES, BLACKBERRIES, PEARS, PEACHES, APPLES, POTATOES

4. BUDDING – OUTGROWTH ON PARENT BREAKS OFF & FORMS WHOLE NEW ORGANISM(EG. SPONGE, HYDRA, YEAST)

5. FRAGMENTATION – CELLS BREAK OFF PARENT TO FORM NEW ORGANISM(EG. BLUE-GREEN ALGAE, SPONGES, COELENTERATES (SEA ANEMONE)

SEXUALUNION OF 2 TYPES OF CELLS (2 SETS OF DNA)• VARIATIONS: OFFSPRING DIFFER FROM

PARENTS• FERTILIZATION: UNION OF GAMETES AFTER

MEIOSIS• MEIOSIS: HAPLOID GAMETES THAT

MAINTAIN SPECIES CHROMOSOME # - FERTILIZATION RESTORES SPECIES #

EXAMPLES (ALL CAN FORM GAMETES):1. SPONGES 2. COELENTERATA3. PLATYHELMINTHES4. ALL OTHER HIGHER ANIMALS5. SOME TYPES OF ALGAE (RED, BROWN,

GREEN)