SEED PLANTS II
The Flowering Plants (Anthophyta)
Anthophyta
Phylum Anthophyta
(Angiosperms)
 Constitutes ~300,000 species (Gymno. 720 spp)
 Most recently evolved & most diverse group
 Divided into many groups:
Basal Angiosperms
Magnoliids (~8500)
Eudicotyledones (dicot)
Monocotyledones (monocot)
Phylogeny of Angiosperms
Basal angiosperms
Fusion
Fusion of Carpel
secretion
fusion
From Endress & Igersheim, 2000
Characteristics of Angiosperms
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Double fertilization:
 egg + sperm produce zygote (2n)
 egg + 2nd sperm produce endosperm (3n)
Mostly closed carpels: enclose ovule
Reduced gametophytes (pollen grain, embryo sac)
Sieve tubes and companion cells (phloem)
Vessels (xylem)
Stamens with 2 pairs of pollen sacs
Chemical evolution!
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Refinements in vascular tissue, especially xylem,
probably played a role in the enormous success of
angiosperms in diverse terrestrial habitats.
 Like gymnosperms, angiosperms have long,
tapered tracheids that function for support and
water transport.
 Angiosperms also have
fiber cells, specialized
for support, and vessel
elements (in most
angiosperms) that
develop into xylem
vessels for efficient
water transport.
Amborella (Basal angiosperms)
Fruit
mailto:stephens@cats.ucsc.
edu
http://www.amborella.org/

Scott Zona
Scott Zona
The plant is dioecious. Female flowers with 5-6 carpels (a).
Male flowers 10-25 stamens (b).
Magnolia (Magnoliids)
Fruit: aggregate follicle
Tulip (Magnoliids)
Differences Between Monocot
& Eudicot
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EUDICOT
MONOCOT
Embryo with single cotyledon  Embryo with two cotyledons
Pollen with a single furrow or  Pollen with three furrows or
pores
pore*
 Flower parts in multiples of four
Flower parts in multiples of
or five
three
 Major leaf veins reticulate
Major leaf veins parallel
 Stem vascular bundles in a
Stem vascular bundles
ring
scattered
 Have taproots
Have fibrous roots
 Secondary growth often present
Secondary growth absent
A Grass Pollen
Pollen of Horse chestnut
Flower: the main feature of angiosperms
(= Carpel)
The Flower
 Perianth:
Sepals & petals collectively
 Androecium: stamens collectively
 Gynoecium: pistils collectively
Types of Flowers
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Complete flower: has all 4 floral parts
 Incomplete flowers: missing a floral part(s)
 Perfect Flower: bisexual
 Imperfect flower: unisexual flowers
 Staminate flowers: have only the stamens
 Pistillate (carpellate) flowers: have only pistils
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Monoecious plants: separate staminate and
pistillate flowers on the same plant
 Dioecious plants: either staminate or pistillate flowers
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Floral symmetry:
Actinomorphic flower: floral parts are of similar shape &
size (radially symmetrical)
Zygomorphic: floral parts are different (bilaterally
symmetrical)
Inflorescence: A cluster of flowers with a definite
arrangement
Fertilization: the fusion of two gamete nuclei to produce a
diploid zygote
Pollination: transfer of pollen from the anther to the stigma
 Pollen transferred within the same flower is called self-
pollination, and the species is an in-breeder
 Pollen transferred to a different flower is called crosspollination and the species is out-breeder
Example of
Example ofMonocot
Monocot Flower:
Flower:
Lilium
sp.
Lilium sp.
Dicot
Example of a Dicot Flower
Hibiscus moscheutos
Dicot
Stamens
Stigmas
Hibiscus II
Filament
tube
Style
Ovary
Ovules
Angiosperm Life
Cycle
Embryo sac
Egg
Microspores
Pollen
Sperm
Megaspores
Meiosis
1n
2n
Fertilization
Zygote
Sporophyte
Development of Pollen
Microsporogenesis: the development of
microspore mother cell (microsporocyte) into
microspores
This involves meiosis
Liliy Flower
Microsporocytes
Microsporocyte undergo Meiosis
Tetrads of Microspores
Pollen
tetrads
Microspores
 4 microspores were produced by meiosis
 Microsporogenesis is complete
Development of Pollen
Microgametogenesis: the development of
microspores into male gametophyte (pollen
grain)
This involves mitosis
Mature Male
gametophyte
Microspores underwent mitosis to produce male gametophytes
Mature Pollen grain
Tube nucleus
The tube nucleus produced the pollen tube
The generative cell produced two sperm nuclei
Development of Female
Gametophyte
 Megasporogenesis: the
megasporocyte
(megaspore mother cell) develops into
megaspores by meiosis
Lilium Ovary
Megasporocyte Before Meiosis
Megasporocyte
Two-nucleate Stage (formed by meiosis)
Four-nucleate Stage (formed by meiosis)
This survives
others die
Functional
Megaspore
Megasporogenesis is
complete
Development of Female
Gametophyte
 Megagametogenesis:
the megaspore
develops into mature female gametophyte
(embryo sac) by mitosis
 Three mitotic divisions follow
First mitotic Division:
2-nucleate embryo sac
2nd Mitotic Division:
4-Nucleate embryo sac
3rd Mitotic Division:
8-Nucleate embryo sac
8-Nucleate embryo sac
2 of 4
Antipodals
Egg & 2
synergids
Pollination &
Fertilization
Pollen Tube
Sperms
Double Fertilization