F LOWERS AND R EPRODUCTION Dr. Gough

F IGURE 09.07A: ( A ) T HE SEPALS OF THIS ROSE FORM A TIGHT COVERING OVER THE REST OF THE FLOWER AS IT DEVELOPS, PROTECTING THE INNER PARTS.

F LOWER S TRUCTURE Ovary Position Protect ovary from pollinators Fig. 9-28

F LOWER S TRUCTURE Stem with leaf-like structures Terminology Pedicel and receptacle Complete vs. incomplete flowers Sepals (calyx) Petals (corolla) Stamens (androecium) Carpels (gynoecium)

R EPRODUCTION Two forms of reproduction Produce identical genetic copies Produce genetically different offspring What conditions favor which form? How does sexual reproduction produce genetically different offspring? Some plants reproduce both ways

A SEXUAL R EPRODUCTION Many methods Fragmentation Rhizomes Stolons

F IGURE 09.02C: ( C ) A LL THE TREES IN THIS PHOTOGRAPH ARE A PART OF THE SAME PLANT, EACH A SPROUT FROM A SINGLE ROOT SYSTEM.

S EXUAL R EPRODUCTION In angiosperms, requires flowers Plant Life Cycle Think of human/animal life cycle Meiosis Fertilization Mitosis More complicated in plants alternation of generations

F IGURE 09.13: T HIS IS THE TIP OF A GROWING POLLEN TUBE. I T WAS TREATED TO MAKE THE NUCLEI FLUORESCE SO THAT THEY CAN BE FOUND DESPITE BEING SO SMALL. Courtesy of S. Muccifora

S EXUAL R EPRODUCTION Fertilization Following pollination Pollen tube growths through style to ovule opening One sperm nucleus fertilizes egg Second sperm nucleus migrates into central cell Only in angiosperms Becomes endosperm Double fertilization

S EXUAL R EPRODUCTION Embryo and Seed Development Zygote continues dividing, growing Embryo Radicle Hypocotyl Epicotyl Monocotyledon Dicotyledon

F IGURE 09.19A: ( A ) T HIS BEAN SEED HAS BEGUN GERMINATING ; THE RADICLE HAS EXTENDED AND WILL DEVELOP INTO A TAPROOT.

F IGURE 09.19C: ( C ) T HE SMALL LEAVES PRESENT ON THE EPICOTYL ARE EXPANDING DURING GERMINATION.

S EXUAL R EPRODUCTION Fruit Development Fruit is a mature ovary

F IGURE 09.21: I N APPLES, THE PETALS DIE AND FALL OFF AFTER POLLINATION.

F IGURE 09.22B: ( B ) C OCONUTS IN STORES ARE USUALLY JUST THE ENDOCARP AND SEED.

F LOWER S TRUCTURE AND C ROSS - P OLLINATION Role of flowers in pollen and seed dispersal Cross-pollination Vs. self-pollination Stamen and style maturation times Stigma and pollen incompatibility

F LOWER S TRUCTURE AND C ROSS - P OLLINATION Monoecious and dioecious species Imperfect vs. perfect flowers Monoecy Dioecy Fig. 9-25

F LOWER S TRUCTURE AND C ROSS - P OLLINATION Animal-pollinated flowers Coevolution between plants and pollinators Plant-insect pollination began about 120 mya What traits were favored? Some birds and bats pollinate too Flower shape Actinomorphic/regular vs. zygomorphic Usually positive relationship, but cheaters on both sides

F RUIT T YPES AND S EED D ISPERSAL More co-evolution! Seed (fruit) dispersal agents Gravity Wind Water Animals Often division of labor within fruit