Transcript seed_plants_lecture_ch._30

Seed
Plants
Classification - Seeds
Seedless Plants
 Mosses & ferns (ferns are
vascular plants) make
spores, not seeds
 Embryo from sexual
reproduction develops
within archegonium in
parent plant
 Embryo does not need to
await favorable conditions
to develop
Seed Plants
 Embryo from sexual
reproduction develops in
seed
 Seeds dispersed, await
favorable conditions to
germinate
 Seeds formed in cone
(gymnosperm) or fruit
(angiosperm)
Classification - Flowers
Flowering Plants:
Angiosperms/Anthophyta
 Seeds enclosed in a fruit
 Flowers make gametes (eggs
& sperm)
 Fertilized flower  fruit
Naked Seed Plants:
Gymnosperms/Coniferophyta
 Seeds in cone
 No flowers
 Male & female cones make
gametes (egg & sperm)
 Conifers: pines, firs, spruces,
cypresses, redwoods
Sexual Reproduction in Seed Plants (ch. 30)
Life Cycle of Coniferophyta/Gymnosperms
Male
gametophyte
(n)
No more spores…
(n)
In pollen cone and
ovule of female
cone:
Meiosis to produce
gametophytes (n)
Mitosis to produce
gametes (n)
Pollination
*Water not needed*
Female
gametophyte
(2n)
(2n)
Life Cycle of Anthophyta/Angiosperms
In anther and ovule:
Meiosis to produce
gametophytes (n)
Mitosis to produce
gametes (n)
Male
gametophyte
Pollination
*Water not needed*
Fertilization
No more spores…
Female
gametophyte
Mitosis
Your
Textbook
picture
Double fertilization:
2 sperm cell + egg +
polar nuclei 
Zygote (2n)
Endosperm (3n)
Seed Germination
 Germination – embryo in seed
starts to grow (usually triggered by
water absorption)
 Radicle – first shoot/part of embryo
to appear outside seed; develops
into root
 Cotyledons – seed “leaves,” not
real leaves, do not photosynthesize
 Monocot  one coteledon
grains: rice, corn, wheat, etc.
 Dicot  two coteledons
legumes: beans, peas, etc.
If April showers bring May flowers,
what do May flowers bring?
Pilgrims.
Botanists have developed a
vegetable that eliminates
the need to brush your teeth.
Bristle sprouts.
Seed Structure & Development in
Flowering Plants
Double fertilization  seeds containing embryo and endosperm
(one sperm for egg, one for endosperm)
Endosperm – contains starch/oil/protein -- energy for developing
embryo
Each ovule develops into a seed. The micropile is the
small opening where sperm came into ovule for
fertilization.
Seed Development
Hypocotyl = embryo shoot under
cotyledons  develops into first
stem
Cotyledons
(seed leaves)
eventually fall
off
Epicotyl = embryo shoot above
cotyledons  develops into first
leaves
Brassica, our lab plant
Bean Seed
Hilum
Scar where ovule
attached to ovary
Radicle emerges here,
becomes root
Micropile
Scar where pollen
tube entered ovule
Development of Bean Plant
cotyledons
epicotyl
hypocotyl
Corn
Kernel /
Seed /
Fruit
Silk Scar
(pollen tube
entered
ovule here)
Embryo
Point of
attachment
Flowers

Sexual reproductive structures (contain gametophytes)
 Attract pollinators
 Make gametes by mitosis



Anther makes pollen containing sperm
Ovary makes ovules  eggs
Seeds/fruits develop from flower ovary
 Pollination – stigma receives pollen, pollen tube forms
 Double fertilization in ovary:
2 sperm cells + egg --> embryo & endosperm
(endosperm = food for embryo)
Flower Structure
(use to label the
diagram in your
notes)
Flower Structure
Perfect/complete Flowers
have both male &
female parts
Imperfect Flowers
have either male or
female parts
Formation of Female Gametophyte -- Terms you need to know/ID:
Ovary, ovule, female gametophyte, meiosis, egg & polar nuclei,
endosperm, double fertilization
Formation of Male Gametophyte -- Terms you need to know/ID:
Anther, male gametophyte (pollen), meiosis, sperm (2, for double
fertilization)
Fruits
Fleshy Fruits
 High moisture content
 Apples, cherries, grapes,
strawberries, tomatoes,
cucumbers, etc.
Dry Fruits
 Low moisture
 Walnuts, acorns, wheat
kernels, dandelion
“parachutes”
Fleshy Fruits
Berry
Pome
Drupe
Aggregate
http://www.csdl.tamu.edu/FLORA/201Ma
nhart/repro/fleshyfruits/fleshyfruits.html
Multiple
Accessory
Dry Fruits
Policidal capsule
Nut
Silique
Follicle
http://www.csdl.tamu.edu/FLORA/201Manhart/
repro/dryfruits/dryfruits.html
Dry Fruits
Samara
Legume
Winged
schizocarp
Asexual Reproduction in Plants


Vegetative reproduction – occurs naturally, very fast, via
modified ground surface/underground stems that make buds:
 Stolons/runners – close to ground surface; ex.: aspen groves
(clones), water hyacinths
 Rhizomes – underground; ex.: bamboo plants
 Tubers – swollen tips of rhizomes; modified for food storage;
ex: potatoes
 Corms and bulbs – modified for food storage; ex.: tulips, onions
Artificial propagation – people do it: cutting, grafting, tissue
culture
 faster than seeds, produces genetically identical crop – plant
regenerates parts
Ex: bananas, apples, grapefruits, grapes, potatoes, pears are often
grown by artificial propagation