George Bentham and Joseph Dalton Hooker
- It described taxa at all levels in an aacurate an easy to follow manner.
- Their decriptions were based on direct observations and these generated accurate data.
- They created errors when they placed primitive gymnosperms beteween dicot and monocot
- They subdivided monocots basing on features of perianth and position of ovary and this geretared anomolous situations for many families.