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Chapter 9: Flowers and Reproduction (Flower Structure and Cross…
Chapter 9: Flowers and Reproduction
Asexual Reproduction
Fragmentation
spreading or vining plant
grows to several meters in length
individual parts become self-sufficient
Sexual Reproduction
The Plant Life Cycle
Diploid adults have sex organs that produce gametes
sperms=produced by males
eggs=produced by females
meiosis
one sperm+one egg=zygote
Sporophyte
Always diploid
Have organs
Spores cannot undergo syngamy
Grow into gametophytes
Mammalian gametes
Microgametes
Small sperm cells
Swim
Megagametes
large eggs
do not swim
Oogamy
microgametophytes (male)
grown from microspores
megagametophytes (female)
grown from megaspores
2 types of spores = heterospory
2 generations
Sporophyte and Gametophyte
Alternation of generations
Flower Structure
Pedicel=flower stalk
Receptacle=end of axis where other flower parts are attached
Floral appendages
Sepals
Lowermost/Outermost
Protect flower
All sepals together=calyx
Petals
All petals make up corolla
Sepals and petals make up the perianth
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Stamens
All stamens are the androecium
Male part
Filament=stalk
Anther=pollen produced here
Carpels
Gynoecium-highest level of receptacle
Stigma-catches pollen grains
Style-elevates stigma
Ovary-produces megaspores
Placentae-inside ovary-regions of tissue with ovules
Ovules carry water and nutrients-have a central parenchyma mass called a nucellus'
In ovules are megasporocytes
Flowers with all four are complete flowers
Gametophytes
Microgametophyte
vegetative cell
generative cell
produces pollen tube
Megagametophyte
embryo sac
7 cells: central cell with two polar nuclei, three small antipodal cells, egg apparatus with two synergids and egg
Fertilization
Plasmogamy-fusion of protoplasts of gamets
Karyogamy-fusion of nuclei
endosperm nucleeus-triploid
double fertilization-both sperm nuclei undergo fusions-one with egg nucleus and one with polar nuclei
endosperm-coenocytic and cellular tissue
Embryo and Seed Development
suspensor-pushes embryo into endosperm
cotyledons-grown from two primordia
embro is elongate cylinder
radicle-embryonic root
epicotyl-embryonic stem
hypocotyl-root/shoot junction
albuminous seed-mature seed with abundant endosperm
exalbuminous-endosperm sparse or absent
seed coat-testa
Fruit Development
exocarp-outer layer
mesocarp-middle layer
endocarp-innermost layer
pericarp=entire fruit wall with one, two, three layers
Flower Structure and Cross-Pollination
Cross-Pollination
pollination of a carpel by pollen from a different individual
self-pollination-pollination of a carpel by pollen of same or another flower on same plant
Stamen and Style Maturation Times
Monoecious and Dioecious Species
essential organs-stamens and carpels
imperfect flowers-lack either or both essential organs not only incomplete
perfect flower-both essential organs but may lack either sepals or petals
nonessential organs-sepals and petals
dioecy-species that produces only carpellate flowers-species is dioecious
monoecy-having staminate flowers located on same plant as carpellate flowers
Stigma and Pollen Incompatibility
compatibility barriers-chemical reactions between pollen and carpels that prevent pollen growth
Animal-Pollinated Flowers
coevolution
actinomorphic-radially symmetrical flowers
zygomorphic-bilaterally symmetrical flowers
Wind-Pollinated Flowers
Ovary Position
inferior ovary
epigynous
superior ovary
hypogynous
half-inferior
perigynous
Inflorescences and Pollination
inflorescence-collective visual signal to pollinators
determinate inflorescences-limited potential
indeterminate inflorescence-lowest or outermost flowers open first
Fruit Types and Seed Dispersal
True Fruits and Accessory Fruits
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true fruit-fruit containing only ovarian tissue
accessory fruit-nonovarian tissue is present
simple fruit-fruit develops from single ovary or fused ovaries of one flower
aggregate fruit-separate carpels fuse
multiple fruit-individual fruits fuse into one
Classification of Fruit Types
dry fruit-not typically eaten by natural seed-distributing animals
dehiscent fruits-break open and release seeds
indehiscent fruits do not break open
fleshy fruit-eaten during natural seed distribution process
