~EVOLUTION OF PLANTS~

[Weirdmaskman]

*The evolution of plants has resulted in increasing levels of complexity, from the earliest algal mats, through bryophytes, Lycopods, ferns to the complex gymnosperms and angiosperms of today.

*MAIN HISTORY.

~Probably an algal scum formed on land 1,200 million years ago.

~In the Ordovician period, around 450 million years ago, the first land plants appeared.

~The fruits of their diversification are displayed in remarkable detail in an early Devonian fossil.

~By the middle of the Devonian period most of the features recognised in plants today are present, including roots, leaves and secondary wood.

~By late Devonian times seeds had evolved.

~Late Devonian plants had thereby reached a degree of sophistication that allowed them to form forests of tall trees.

The summary of the evolution goes thus;

1. Colonisation of land

2. Evolution of stomata and vascular tissues

3. Evolution of water transport

4. Evolution in Morphology

5. Evolution in leaves

6. Shape and size

7. Evolution of flower

8. Evolution of roots

9. Advances in metabolism

10. Concentrating carbon. {not sequencial though}....

[Moontanman]

*The evolution of plants has resulted in increasing levels of complexity, from the earliest algal mats, through bryophytes, Lycopods, ferns to the complex gymnosperms and angiosperms of today.

*MAIN HISTORY.

~Probably an algal scum formed on land 1,200 million years ago.

 

I think you are missing something of huge importance, even 1.2 billion years ago algae had evolved past the "scum" stage

 

http://en.wikipedia.org/wiki/Red_algae

 

The oldest fossil identified as a red alga is also the oldest fossil eukaryote that belongs to a specific modern taxon. Bangiomorpha pubescens, a multicellular fossil from arctic Canada, strongly resembles the modern red alga Bangia despite occurring in rocks dating to 1200 million years ago. [1]

 

Red algae are important builders of limestone reefs. The earliest such coralline algae, the solenopores, are known from the Cambrian Period. Other algae of different origins filled a similar role in the late Paleozoic, and in more recent reefs.

 

There are also calcite crusts, which have been interpreted as the remains of coralline red algae dating to the terminal Proterozoic.[8] Thallophytes resembling coralline red algae are known from the late Proterozoic Doushantuo formation.[9]

 

 

By the cambrian period marine algae had evolved into what we would call "seaweed" Marine plants were already quite complex before the first land plants and marine algae are still more important as far as the oxygen levels of the Earth than land plants.

 

 

In the Ordovician period, around 450 million years ago, the first land plants appeared.

 

I am not trying to be argumentative here but marine algae are far from slime and by the time marine algae began their assault on land they would have been recognized as higher plants by us had we been there. I think the evolution of marine macro algae is somewhat ignored by most people when they think of evolution in favor of the exciting creatures we call animals.... while not exactly a scientific term seaweeds are a diverse group of complex organism that had already diversified greatly in both complexity, size, and numbers by the time plants began to appear on land. Think of a kelp forest instead of scum.

 

[Weirdmaskman]

I think you are missing something of huge importance, even 1.2 billion years ago algae had evolved past the "scum" stage

 

http://en.wikipedia.org/wiki/Red_algae

>yeah, thanks for the correction, i think i got the figure wrong.

 

 

 

 

I am not trying to be argumentative here but marine algae are far from slime and by the time marine algae began their assault on land they would have been recognized as higher plants by us had we been there. I think the evolution of marine macro algae is somewhat ignored by most people when they think of evolution in favor of the exciting creatures we call animals.... while not exactly a scientific term seaweeds are a diverse group of complex organism that had already diversified greatly in both complexity, size, and numbers by the time plants began to appear on land.

ok! Prokaryotes were believed to have inhabited the earth from approximately 3-4 billion years ago. "no obvious changes in morphology or cellular organisation occured in these organisms over the next few billion years." This shows that their evolution happens to be the longest, hereby making them the most primitive.

Monera, where algaes belong according to R.H whittaker's classification <1969> are the most primitive, lack nucleus, lack membrane bounded organelle, et cetera. This and the fact that they evolved billions of years before animals evolved should have been the reason for the neglect. :-D.ciao

[Moontanman]

ok! Prokaryotes were believed to have inhabited the earth from approximately 3-4 billion years ago. "no obvious changes in morphology or cellular organisation occured in these organisms over the next few billion years." This shows that their evolution happens to be the longest, hereby making them the most primitive.

Monera, where algaes belong according to R.H whittaker's classification <1969> are the most primitive, lack nucleus, lack membrane bounded organelle, et cetera. This and the fact that they evolved billions of years before animals evolved should have been the reason for the neglect. :-D.ciao

 

 

Your classification is out of date, only blue green algae, that are now called cyanobacteria, are prokaryotes, my links point this out, the other algae are all Eukaryotes and complex plants not scum... they are sometimes hundreds of feet long and have complex structure, reproduce sexually and most importantly are Eukaryotes just like trees and other land plants.

[Weirdmaskman]

Your classification is out of date, only blue green algae, that are now called cyanobacteria, are prokaryotes, my links point this out, the other algae are all Eukaryotes and complex plants not scum... they are sometimes hundreds of feet long and have complex structure, reproduce sexually and most importantly are Eukaryotes just like trees and other land plants.

I made it clear there that my classification is based on whittaker's classification, though, new discoveries has been made which might have made his classification out of date, i see it as the most acceptable.

New things are learnt everyday! I'v made some research and have got your point. Thanks.