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NATURAL SYSTEM OF PLANT CLASSIFICATION ACCORDING TO CHARLES BESSEY BY: ASHLEY BECK
WHAT IS THE NATURAL SYSTEM? q A phylogenetic system of organizing flowering plants with the use of genetic techniques. q Besse’s theory was based off of evolution.
THE NATURAL SYSTEM q q “Besse’s cactus” was based on his 28 rules, which show the evolutionary trends in angiosperm. The most direct path represents the actual evolutionary history of a given group.
THE NATURAL SYSTEM q q q The most primitive, original flower was believed to have had many separate petals, stamens, and carpels. As they evolved the parts of the flowers either fused together, reduced, or became absent. The simple structures are not primitive, but have become simple as a result of a reduction from more complex parts.
THE NATURAL SYSTEM q An example of the primitive flower would be the Ranunculus, buttercup flowers.
THE NATURAL SYSTEM q A more advanced type of flowering plant would be the catkin inflorescences.
Natural System of Plant Classification By: Thursday lab Charles Bessey 1845 -1915
Bessey n Published Work: The Phylogenetic Taxonomy of Flowering Plants
Charles Bessey n He developed a set of rules or “dicta” stating which characteristics were primitive an which were advanced in flowering plants.
Natural System n A natural system is one which reflects the evolutionary relationships of the organisms. In this type of classification, all the members of a category (family, order, etc. ) are known or presumed to be monophyletic, meaning they share a common ancestor.
Those who started the Natural System were observing overall resemblances amongst plants, then making evolutionary connections. Similar to differences amongst