Lab
• Pine Lifecycle
• Lilly Lifecycle
Dates for plant group origins:
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Mosses 475
Ferns 420
Gymnosperms 360
Angiosperms 160
The Pine Life cycle Fig. 30.9
PHYLUM CYCADOPHYTA
PHYLUM GINKGOPHYTA
Cycas revoluta
PHYLUM GNETOPHYTA
Gnetum
Welwitschia
Ovulate cones
Ephedra
PHYLUM CONIFEROPHYTA
Douglas fir
Common juniper
Wollemia pine
Pacific yew
Bristlecone pine
Sequoia
Gnetophytes
• 3 genera: Welwitschia, Ephedra, Gnetum
• Mostly dioecious
• Have more Similarities to angiosperms:
– Have vessel elements,
– Lack archegonia (except Ephedra)
– Two sperm nuclei in pollen. Fertilizes two eggs in
some groups. Analogous to double fertilization n
angiosperms
• Morphologically diverse group, grouped by
genetic comparisons
• Common ancestral pool long gone, a few remote
descendents remaining.
Gingko
biloba
• Dioecious, heterosporous
• Dichotomous venation
• Deciduous
Cycads
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Leaves look like palms, ferns
Makes cones
Dioecious, herterosporous
Pollen tube produces sperm inside !!
Pollen (Staminate) Cone:
• Produced yearly
• Short lived- die after
releasing pollen
• Different species release pollen
at different times to avoid hybridization
• The male cone has the microsporangia on scale-like
sporophylls .
– (n) microspores from by meiosis
– They develop into pollen grains
– Produces millions of pollen grains per branch
• Carried by wind- random mating
Pollen
• are the male gametophytes
– just 4 cells !
– generative cell forms the pollen tube
– Pine pollen have wing cells to keep them afloat
in air
• are covered with a tough sporopollenin.
• are carried away by wind or animals until
pollination occurs.
• pollen grain will elongate a tube into the
ovule and deliver sperm (nuclei) into the
female gametophyte via pollen tube
• No longer need film of water to fertilize
Ovulate cone
• very small and fleshy when young
• Forms the “Pine Cone” with seeds
– often matures over 2-3 years
• form on branch tips to catch pollen
• 2 megasporangia form on each scale or
sporophyll
– Megasporangia form 2 ovules
– They become the 2 mature
seeds per scale in the pine cone
Ovule
• Forms inside female (ovulate) cone
• Megasporangia on sporophylls under go
meiosis – one surviving (n) megaspore.
• Megaspore grows inside by mitosis
integuments (2n) to become female
gametophyte
– With 3 archegonia and eggs (pine).
• Zygote develops into embryo, inside nutritive
female gametophyte tissue.
• Embryo goes dormant, integuments harden
and ovule now becomes a seed
Pine ovule
Pine Megasporangia : ovulate cone
Pine Ovule; female gametophyte &
Archegonia
Pine
Microsporangia & pollen
Staminate
Ovulate
Pine pollen & pollen tube
Angiosperms
• Flowers – attract pollinators
• Ovary = Fruit
• Ovules ( inside)=seeds
The flower
• Sepals
• Petals
• Stamens (male)
– Anther - pollen
– Filament
• Carpel (female)
–
–
–
–
Stigma
Style
Ovary
Ovule-eggs
Figure 30.13 Flower-pollinator
relationships
(a) A flower pollinated by honeybees.
(b) A flower pollinated by hummingbirds.
This honeybee is harvesting pollen
The long, thin beak and tongue of this
and Nectar (a sugary solution secreted
rufous hummingbird enable the animal
by flower glands) from a Scottish
to probe flowers that secrete nectar
broom flower. The flower has a tripping
deep within floral tubes. Before the
Mechanism that arches the stamens
hummer leaves, anthers will dust its
over the bee and dusts it with pollen,
beak and head feathers with pollen.
some of which will rub off onto the
Many flowers that are pollinated by
stigma of the next flower the bee visits.
birds are red or pink, colors to which
bird eyes are especially sensitive.
(c) A flower pollinated by nocturnal animals.
Some angiosperms, such as this cactus,
depend mainly on nocturnal pollinators,
including bats. Common adaptations
of such plants include large, light-colored,
highly fragrant flowers that nighttime
pollinators can locate.
The life cycle of an angiosperm
Key
Haploid (n)
Diploid (2n)
Anther
Microsporangium
Microsporocytes (2n)
Mature flower on
sporophyte plant
(2n)
MEIOSIS
Microspore (n)
Ovule with
megasporangium (2n)
Generative cell
Tube cell
Male gametophyte
(in pollen grain)
Ovary
Stigma
Megasporangium
(n)
Embryo (2n)
Endosperm
(food
supply) (3n)
Pollen
tube
Sperm
Surviving
megaspore
(n)
Seed
Seed coat (2n)
Female gametophyte
(embryo sac)
Nucleus of
developing
endosperm
(3n)
Pollen
grains
MEIOSIS
Germinating
seed
Antipodal cells
Polar nuclei
Synergids
Egg (n)
Zygote (2n)
Egg
nucleus (n)
Pollen
tube
Sperm
(n)
FERTILIZATION
Discharged
sperm nuclei (n)
Pollen
tube
Style
Gametophyte growth
Angiosperm seed formation
Flower cross section # 52
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Ovules
Pistil
Anthers
Petals
Sepals
• Germinating
pollen
Lilly Anther