BIOL 1030 Lecture Notes - Gymnosperm, Gynoecium, Coevolution
7 May 2018
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Lecture 26: Angiosperms and Gymnosperms (part II)!
Angiosperms: flowering plants
-Monocots: Lilies, orchids, grasses!
-Dicots (Eudicot): elms, willows, roses, peas, canola!
Flower structure:
-Sepals: green and leaf-like, enclosing other flower parts (bud)!
-Petals: often pigmented to attract pollinators, form can be co-evolved with pollinators;
wind pollinated plants have very reduced flowers!
-Stamen: Filament, Anther (containing 4 microsporangia)!
-Carpel (in angiosperms only): !
•Stigma: receives pollen, site of pollen tube germination!
•Style: elevates stigma to make it more accessible to pollinators!
•Ovary: encloses and protects the ovule (will become the fruit)!
•Nectaries: may be present at base of petals, offering sugar reward to pollinators, help
to align pollinators.!
Types of fruit:
•Simple fruit: pea fruit (protected)!
•Aggregated fruit: many carpels (fruitlets)!
•Multiple fruit: many flowers on a stalk/stem!
Example: Corn!
-Each grain (kernel) has one flower origin!
-Long silk is the style!
-Each grain has a female gametophyte!
-Each seed is genetically different!
-Corn cob is population of individuals!
Life Cycle,
Double fertilization:!
-Syngamy of sperm and egg to make the zygote (2N)!
-Triple fusion (second fertilization): a second sperm fuses with two polar nuclei to make the
triploid endosperm which will provide nutritive tissue to the developing embryo.!
•No nutritive tissue is provisioned until fertilization occurs, this process is less wasteful if an
embryo does not form.!
$Seeds and dispersal:
-Fruit develops to attract animals (berries)!
-Symbiosis, specific pollinators are offered nectar!
-Wind transport requires wings to transport the seed !
Monocots
Eudicots
Embryo
One cotyledon
Two cotyledons
Venation
Parallel veins
Forming a network
Stem
Scattered vascular tissue
Neat ring organization for new tissues
Roots
Fibrous (no main root)
Tap root (one main root0
Pollen grain
Single pore
Three openings
Flowers
Flower organs in multiples of 3
Flower organs in multiples of 4 or 5
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BIOL 1030 Full Course Notes
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Document Summary
Dicots (eudicot): elms, willows, roses, peas, canola. Sepals: green and leaf-like, enclosing other ower parts (bud) Petals: often pigmented to attract pollinators, form can be co-evolved with pollinators; wind pollinated plants have very reduced owers. Types of fruit: simple fruit: pea fruit (protected, aggregated fruit: many carpels (fruitlets, multiple fruit: many owers on a stalk/stem. Each grain (kernel) has one ower origin. Flower organs in multiples of 4 or 5. Syngamy of sperm and egg to make the zygote (2n) Wind transport requires wings to transport the seed. Fruit: serves to protect the seed inside and can play a role in the dispersal of the seed. Gymnosperms: naked seed, ovules are exposed and seed are on the surface of ovuliferous scales, they have no fruits or owers. Pollen is transported to the ovule, with a pollen tube delivers sperm to egg. Seed contains nutritive tissue is derived from the megagametophyte.
