lecture #11- Basal Angiosperms Flashcards
When were the earliest angiosperm fossils found?
130MYA
What are Gigantopterids?
They could be the common ancestor of the Angiosperms and Gnetales
- have primitive vessels
- Eusteles
- thought to be a seed fern by some
How would Gigantopterids help Darwins mystery?
The abominable mystery, gigantopterids would help like the “sudden appearance of angiosperms”
-have morphological similarities but molecularly not similar
Did basal angiosperms have flowers?
No, not what we would consider flowers
What is a carpel?
The female reproductive untie of angiosperms
-derived from a leaf
What was characteristics about carpels when they were first invented?
They were imperfectly fused
Where are the ovaries in a carpel?
In the bottom part
What is a fruit?
Matured ovary that contains the seed
What kind of pollen did early anglos have?
Pollen grains with one pore
-monocolpate
What was the purpose of the pore of the pollen?
Pore is where the pollen would germinate
What kind of pollen do more advanced anglos have?
Pollen grains with 3 pores
- tricolpate
- 127MYA
What were the 2 competing hypotheses for the origin of angios based on morphology?
- Paleoherb
2. Woody Magnolid
What is the Paleoherb hypothesis?
Suggests the earliest angios were a groups of tropical flowering plants with uncomplicated flower
-mix of monocot and dicot features
What is a Paleoherb?
Polyphyletic group of non-woody basal angiosperms
What is the Woody Magnolid Hypothesis?
Suggests that early angios had a morphology similar to loving members of the the Magnolids and Lavales
- plants had medium sized trees awith long branched leaves and large flowers
- carpel imperfectly fused
- was the closest hypothesis
What is Amborellales?
Oldest extant angiosperm
How did insect pollination arise?
From organisms looking for food
-they don’t know that they are pollinating
What is double fertilization?
2 sperm nuclei
- one fertilizes the egg to produce a 2n zygote
- and the other uniting with the 2 polar nuclei to form a 3n endosperm
Whats the difference between the food reserves of a gymno and an angio?
gymno has n (megagametophyte tissue)
Angio has 3n (endosperm)
What happens to the ovules in angios?
Ovary is enclosing ovules
Where is the pollen produced?
On the Anthers
What is the first monophyletic group in the angios?
Magnolids
Why was Ceratophyllum thought to be primitive?
Thought because its aquatic
- reduced simple leaves
- flower were simple
- actually went into the water after flowering plants developed
Fossil vs molecular evidence of angiosperms?
Fossils 125MYA
Molecular 200-250MYA
What mad angios so successful?
Adapted traits to resist drought and cold
- small tough leaves
- vessels
- being deciduous
- sieve tube elements
- specialized pollination
- seed dispersal mechanisms
- chemical defence diversity
- mycorrhizal relationships
Why are flowers what they are today?
Selective forces for pollination, protection from predation and eventual dispersal of seeds or fruit have shaped what flowers are today
