Group Three
Conifer Life Cycle Snapshot
Seeded
vascular plants (ex: gymnosperms)
Seeded, vascular plants (ex: gymnosperms)
Cycad
phase
• Sporophyte phase – Dominant stage
– Cones grow on tree
Cones grow on tree
• Female cones produce egg & seed
• Male cones produce pollen
– Pollen reaches end of female scale and sticks to ovule
l
d ti k t
l
• Pollen tube grows from p
pollen
• Sperm travels down pollen tube (zygote/seed created)
• Sporophyte stage restarts
Ginkgo
Conifer
What are the other types of gymnosperms?
What are the other types of gymnosperms
• Characteristics:
• Vascular system allows nutrient transport to greater heights
• Seeds not enclosed in fruit (angiosperms); produced inside cones
• Advantages of seed plants
• Seeds allow for reproduction without free‐standing water = Pollen
• Seeds nourish and protect the growing plant embryo = Endosperm , seed coat, dormancy
• Seeds allow plants to disperse to new places = Wind, water, animals
Seeds allow plants to disperse to new places Wind water animals
• Conifer sporophyte is the typical tree like structure • Conifer gametophytes are inside the male/female cones
The sporophyte is the dominant phase for seed plants
for seed plants
See appendix B in your text book
1) Male and female seed cones grow on adult sporophytes
2) Pollen grains released from the male seed cones
‐‐ Pollen is the male gametophyte
Let’s zoom into the female seed cone…
3) Pollen grain sticks to the female ovule
4) Pollen tube grows from the male spore
5) Two nuclei transfer into female spore
5)
Two nuclei transfer into female spore
‐ one fertilizes the egg
6) Diploid embryo develops (sporophyte stage restarts)
6) Diploid embryo develops (sporophyte
stage restarts)
7) After seeds harden, the cone reopens and the seeds are released
8) Seed will land
Ground
9) Seedling grows into (sporophyte)…the cycle repeats
9) Seedling grows into (sporophyte)…the cycle repeats
Ground
Ground
Plant Life Cycle Comparisons
Plant Life Cycle Comparisons
Plant type
Moss
Sporophyte
Gametophyte
SStalk with cup at tip, which lk i h
i
hi h More familiar, carpet‐
f ili
is where spores are like plant that produces produced.
specialized gametes
g
XX ‐ Archegonium
XY ‐ Antheridium
Dominant Phase?
G
GAMETOPHYTE
O
Fern
More familiar, leafy plant with clusters of spore producing sacs (sori)
Haploid plant body (prothallus) is size of a finger nail, produces both male and female parts
SPOROPHYTE
Conifer
(Gymnosperm)
More familiar‐ like pine trees, produces male and female cones that produce p
spores
Male gametophytes are pollen grainsÆ
sperm
p
Female gametophytes are microscopicÆ eggs
SPOROPHYTE