PLANT REPRODUCTION AND DEVELOPMENT CHAPTER 38 PLANT REPRODUCTION AND DEVELOPMENT

I. SEXUAL REPRODUCTION A.     SPOROPHYTE AND GAMETOPHYTE GENERATIONS ALTERNATE IN THE LIFE CYCLES OF PLANTS: A REVIEW THE SPOROPHYTE, THE DOMINANT GENERATION, PRODUCES SPORES THAT DEVELOP INTO MALE GAMETOPHYTES (POLLEN GRAINS) AND FEMALE GAMETOPHYTES (EMBRYO SACS).

THE FOUR FLORAL ORGANS ARE: SEPALS PETALS STAMENS (WHICH FORM POLLEN) A.     MALE AND FEMALE GAMETOPHYTES DEVELOP WITHIN ANTHERS AND OVARIES, RESPECTIVELY THE FOUR FLORAL ORGANS ARE: SEPALS PETALS STAMENS (WHICH FORM POLLEN) CARPELS (WHICH FORM EMBRYO SACS WITHIN THE OVULES OF OVARIES). POLLEN DEVELOPS FROM MICROSPORES WITHIN THE SPORANGIA OF ANTHERS; EMBRYO SACS DEVELOP FROM MEGASPORES WITHIN OVULES.

C. POLLINATION BRINGS FEMALE AND MALE GAMETES TOGETHER POLLINATION, WHICH PRECEDES FERTILIZATION, IS THE PLACING OF POLLEN ON THE STIGMA OF A CARPEL.

D. THE OVULE DEVELOPS INTO A SEED CONTAINING AN EMBRYO AND A SUPPLY OF NUTRIENTS THE SEED COAT ENCLOSES THE EMBRYO, COMPLETE WITH APICAL MERISTEMS AND COTYLEDONS, ALONG WITH A FOOD SUPPLY STOCKED EITHER IN THE COTYLEDONS PARTS: EPICOTYL: YOUNG SHOOT TIP PLUMULE: YOUNG LEAVES HYPOCOTYL: YOUNG SHOOT RADICLE: YOUNG ROOT COLEOPTILE: YOUNG LEAVES (IN MONOCOTS)

E. THE OVARY DEVELOPS INTO A FRUIT ADAPTED FOR SEED DISPERSAL THE FRUIT PROTECTS THE ENCLOSED SEEDS AND AIDS IN WIND DISPERSAL OR IN THE ATTRACTION OF SEED-DISPERSING ANIMALS.

F. EVOLUTIONARY ADAPTATIONS OF SEED GERMINATION CONTRIBUTE TO SEEDLING SURVIVAL GERMINATION, WHICH BEGINS WHEN THE SEED RETAINS WATER, OFTEN REQUIRES ENVIRONMENTAL CUES, SUCH AS TEMPERATURE OR LIGHTING CHANGES.

II. ASEXUAL REPRODUCTION A. MANY PLANTS CAN CLONE THEMSELVES BY ASEXUAL REPRODUCTION ONE IMPORTANT MODE OF ASEXUAL REPRODUCTION IS THE FRAGMENTATION OF A PARENT PLANT INTO PARTS. B. VEGETATIVE PROPAGATION OF PLANTS IS COMMON IN AGRICULTURE CLONING PLANTS FROM CUTTINGS IS AN ANCIENT PRACTICE. WE CAN NOW CLONE PLANTS FROM SINGLE CELLS, WHICH CAN BE POETICALLY MANIPULATED BEFORE CLONING.

ASEXUAL REPRODUCTION ENABLES SUCCESSFUL CLONES TO SPREAD A.     SEXUAL AND ASEXUAL REPRODUCTION ARE COMPLEMENTARY IN THE LIFE HISTORIES OF MANY PLANTS: A REVIEW ASEXUAL REPRODUCTION ENABLES SUCCESSFUL CLONES TO SPREAD SEXUAL REPRODUCTION GENERATES THE GENETIC VARIATION THAT MAKES ADAPTATION POSSIBLE.