3 of 3

Write now Article Tools

The plant kingdom is divided into various Phyla depending on their evolutionary age or relation to each other. First Monera-or single celled plants include the algae or phytoplankton.These are the oldest plants in the world. They are simple, single celled bearing chloroplast and mitrochondria. The mitrochodria are more present in the animal branch of monera or protozoa.
The second class of plants are the seaweeds. These including sea lettuce and kelp are considered the second oldest branch in the phylogenetic tree. They have leaves,made up of spongiform cells filled with chloroplast. The xylem or stem cells which normally transport the processed sugar to the body are missing. Only in the more advanced seaweeds does one see the beginnings of a xylem tracheid system.
The third class of plants are the ferns and mosses. They are extremely simple.They reproduce with azygotic spores most of the time.Sexual reproduction occurs rarely. They just divide,yet the life cycle begins again with the zygote in an animal phase.The archaegonium or female spore is amoeba-like and (if females are present)enjoy a totally separate life cycle than the father or mother plant.
The fourth cloass of plants are the beginnings of the land plant.The compositae or sedges. These simple grasses are found along any coast. Their representative species is the Sunflower. Here there is the xylem-trachaid syste. Yet their is no fruit development yet. What is simply termed an inflorescence occurs, much like a cocklespur. The seed has not entirely been born. Again, a cambium-or trunk of roots or the limbs is yet to be there. The3 evolutionary trend towards a sophisticated, sugar producing,Oxygen making organism is just beginning to be born
From the early evolution of plants,it is seen that they first arised from water. The evolutionary time-span for them to reach the land plants such as trees and other plants including flowers,hedges etc must have been huge. It is a history of very stable, evolutionary advances over millions and millions of years.

Learn more about this author, jf.
Click here to send author comments or questions.

Add your voice

Know something about Evolution of plant species?
We want to hear your view. Write now!