Most people think identifying plants is easy- "It's not hard, anyone can do it", they glibly say. An excellent quote below from Dr. M. (aka Jonathan Mitchley from Reading University) talking about teaching botany debunks the myth. To do it, you need:
"Skills such as looking carefully at plants, taking in all the vegetative and floral details using the hand lens, practicing keying using the veg key and the Book of Stace and checking the results carefully by reading the descriptions and making sure the plant fits the description. Important skills these, and skills which can be taught, but which can only really be learned through botanical dedication, concentration and love!"
How very true!