As the concept of evolution came to light by Charles Darwin and 

others, there was a move to reflect which groups gave rise to 

other groups, an overview of evolution

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Many of the traits used in natural systems contributed but some new 
ideas were bandied about, such as which flowers are “primitive” and 
which “advanced”, an indication of when the groups evolved

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These systems are called 

phylogenetic

, and all systems since have been of 

this kind

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You might be tempted to think that we could figure out the evolution of 
plants but we still are working at it

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Most flowers do not fossilize, so depending on the fossil record, use in 
preparing these systems is seldom important

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Often only fragments of plants are fossilized, and we don’t really know if a 
leaf fragment goes with a wood fragment

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Thus, most of the basis for phylogenetic systems has been selecting 
characters that are supposedly ancestral and others that are derived. 
Specializations often indicate this idea.