2. Introduction to Coniferophyta
Characteristics
- Mostly tall trees w/ persistent central trunk. Fir
- Many are long-lived. Yew Pine
- Mostly evergreen.
Fern
- Needle-like or scale-like leaves.
Cedar Birch
- Produce cones.
- No outer-covering or shell around their seeds.
Larch
- Reproduce via wind pollination. Cypress Spruce
- Do not bear fruits.
- Produce different male & female spores Redwood
(heterosporous). Hemlock Juniper
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3. Introduction to Coniferophyta
What distinguishes them from other member of the same kingdom?
Pollination
- Angiosperms rely on plants & animals: This helped with the evolution of
flowers to entice the insects and animals to spread their pollen.
- Gymnosperms rely on wind as their main source of pollination, which leads
to trees with very similar genotypes in a very concentrated area.
Time from pollination to fertilization
- Angiosperms: Pollinate & fertilize almost simultaneously.
- Gymnosperms: Pollen often sits within the cone for up to 15 months or
more before fertilization occurs.
Double fertilization
- Angiosperms: One sperm fertilizes the egg while the other combines to
form an endosperm.
- Gymnosperms: No double fertilization.
Fruit
- Angiosperms: Produce fruit, evolve with mammals to entice animals to
spread pollen.
- Gymnosperms: Seeds without fruit.
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4. Introduction to Coniferophyta
Characteristics to distinguish the
genera & species from one another
- Size/shape of cone produced
- Size/shape of leaves
- Length of lifespan
- Arrangement of leaves
- Pollen grains
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5. Two extinct
members of this 68 genera and 630
phylum:
species
in the phylum.
- Cheirolepidiaceae
- Walchiaceae
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7. Environment & Habitat
It is NOT survival dependent on the presence of other organisms.
There are not any particular, special conditions it needs to
grow and survive. Although, typical conditions include dry
areas, long cold seasons or nutrient deficient soils such as
acidic swampy mucks or sandy areas of the West.
The organism lives in both hemispheres. It dominates
forests of Western US and Canada as well as tropical
regions.
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8. Life Cycle (Reproduction)
The life cycle is a slow, two-year process.
1. To fertilize the ovum, the male cone releases pollen
that is carried on the wind to the female cone. (Male
and female cones can be found on the same plant)
2. The pollen fertilizes the female gamete (located in the
female cone).
3. A fertilized female gamete (called a zygote) develops
into an embryo.
4. Along with integument cells surrounding the embryo,
a seed develops containing the embryo. This is an
evolutionary characteristic of the gymnosperms.
5. Mature seed drops out of cone onto the ground.
6. Seed germinates and seedling grows into a mature
plant.
7. When the plant is mature, the adult plant produces
cones and the cycle continues.
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9. Life Cycle (Reproduction)
Oldest living conifer is over 4,700 years
old.
Reproduction occurs every 12-14
months.
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10. Genetics, Phylogenetics, Evolution
Have genetic studies on this organism revealed new insights as to how
this organism is related to members of other phyla?
Yes, the diversification of Conifers during the Mesozoic helps to mark a
significant change in the world's flora. Paleozoic flora was dominated by
ferns and clubmosses (Paleophytic flora). The Paleophytic flora gave way
to a Mesophytic flora during the Triassic period. Woody seed-bearing
plants and their relatives dominated Mesophytic flora. Thus, the change
from Paleophytic to Mesophytic represented a change in reproductive
strategy; from spore producers to seed producers. Conifers, cycads, and
ginkgoes diversified during this time and dominated the landscape
(Kenrick & Davis, 2004, p. 143).
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