Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 35 Reproduction in Flowering Plants
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants A flower may contain Sepals Petals Stamens Carpels (pistils)
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants An Arabidopsis thaliana flower
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Sepals Cover and protect the flower parts when the flower is a bud Petals Play an important role in attracting animal pollinators
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Stamens Produce pollen grains Each stamen consists of –A filament attached to an anther –An anther (a saclike structure) Carpel Female reproductive unit
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Pistil May consist of either –A single carpel or –A group of fused carpels Each pistil has three sections –Stigma for pollen grains to land on –Style for pollen tube to grow through –Ovary containing one or more ovules
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Cutaway view of an Arabidopsis flower
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Pollen Forms within pollen sacs in the anther Each pollen grain contains two cells –One generates two sperm cells –The other produces a pollen tube so sperm cells can reach the ovule
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants In the ovule the following are formed An egg Two polar nuclei Several other nuclei Both egg and polar nuclei participate directly in fertilization
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Development of female and male gametophytes
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Insect-pollinated flowers Often yellow or blue Have a scent Bird-pollinated flowers Often yellow, orange, or red Do not have a strong scent
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Ultraviolet markings on insect-pollinated flowers
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Bat-pollinated flowers Often have dusky white petals Are scented Wind-pollinated flowers Often have smaller petals or none at all Have neither scent nor nectar Make large amounts of pollen
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Animal pollinators: Archilochus colubris obtains nectar
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Animal pollinators: Leptonycteris curasoae obtains nectar
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Wind pollination
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Coevolution Reciprocal adaptation Caused by two species –Forming interdependent relationship –Affecting the course of each other’s evolution E.g., certain showy flowers + bees
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Pollination Transfer of pollen grains from anther to stigma Fertilization Fusion of gametes Occurs after pollination
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Pollination, pollen tube growth, and fertilization
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Double fertilization In the ovule, egg fuses with first sperm cell Zygote is formed Zygote develops into a multicellular embryo in the seed
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants A longitudinal section through a heart-shaped fruit of Capsella bursa-pastoris reveals numerous tiny seeds, each containing a mature embryo. Each seed developed from an ovule.
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Double fertilization, cont. Two polar nuclei fuse with second sperm cell Triploid nutritive tissue (endosperm) is formed
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Stages of embryo development Dicot embryo develops in the seed –From proembryo –To globular embryo –To heart stage –To the torpedo stage
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants The proembryo in Capsella bursa-pastoris (the ovule is shown apart from the ovary) As cell division continues, the embryo becomes a ball of cells, called the globular stage
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants As the two cotyledons begin to emerge, the embryo is shaped like a heart The cotyledons continue to elongate, forming the torpedo stage
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Mature flowering plant embryo consists of A radicle A hypocotyl A plumule Cotyledons (one in monocots, two in dicots)
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants For use during germination, a mature seed contains both A young embryo Nutritive tissue (stored in endosperm or cotyledons)
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants A maturing embryo within the seed. The food originally stored in the endosperm has been almost completely depleted during embryonic growth and development; most of the food for the embryonic plant is stored in its cotyledons
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Ovules Structures with the potential to develop into seeds Ovaries Structures with the potential to develop into fruits
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Seeds Enclosed within fruits Fruits Mature, ripened ovaries
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Simple fruits Develop from a single pistil consisting of –Either a single carpel –Several fused carpels Some are fleshy at maturity Others are dry
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Aggregate fruits Develop from a single flower with many separate ovaries Multiple fruits Develop from the ovaries of many flowers growing close together on a common axis
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Cutaway view of a Rubus flower, showing the many separate carpels in the center of the flower A developing blackberry fruit is an aggregate of tiny drupes. The little “hairs” on the blackberry are remnants of stigmas and styles
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Accessory fruits The major part of the fruit consists of tissue other than ovary tissue Dispersal methods of seeds and fruits include Animals Wind Water Explosive dehiscence
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants An accessory fruit
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Stems specialized for asexual reproduction Rhizomes Tubers Bulbs Corms Stolons
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Rhizome Horizontal underground stem Tuber Fleshy underground stem enlarged for food storage
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Irises have horizontal underground stems called rhizomes. New aerial shoots arise from buds that develop on the rhizome
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Potato plants form rhizomes, which enlarge into tubers (the potatoes) at the ends
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Bulb Modified underground bud with –Fleshy storage leaves attached to –Short stem Corm Short erect underground stem covered by papery scales
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants A bulb is a short underground stem to which overlapping, fleshy leaves are attached; most of the bulb consists of leaves
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants A corm is an underground stem that is almost entirely tissue surrounded by a few papery scales
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Stolon Horizontal aboveground stem with long internodes Plantlets (detachable) Arise from meristematic tissue along margins of some leaves
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Strawberries reproduce asexually by forming stolons, or runners; new plants (shoots and roots) are produced at every other node
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Plantlets
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Suckers Develop from adventitious buds developed from roots Produce additional roots May give rise to new plants
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Apomixis Production of seeds and fruit without sexual reproduction Sexual reproduction Involves union of two gametes Offspring produced are genetically variable
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Sexual reproduction, cont. Parental genotypes are not preserved in offspring Genetic diversity among offspring –May be selectively advantageous –May let individuals exploit new environments
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Sexual reproduction, cont. Costly because both male and female gametes –Must be produced –Must meet
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Asexual reproduction Involves formation of offspring without fusion of gametes Offspring are virtually genetically identical to single parent –Genetic similarity may be selectively advantageous
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 35 Reproduction in Flowering Plants Asexual reproduction, cont. All individuals can produce offspring Genetic variability is increased by occasional sexual reproduction