That said, there are irritating errors in the book.
First, Florey gets the details wrong about the early history of sentence diagramming. She claims that Reed and Kellogg introduced their system first in 1877, in a book called Higher Lessons in English. This book was actually the second one that they published. They used the same system in an earlier book, Graded Lessons in English, which was first published in 1875. She also states that Clark's A Practical Grammar, the most influential sentence diagrammer before Reed and Kellog, was published in 1860. The first edition was actually in 1847.
And then there are mistakes in her diagrams. Consider this one, which I have redrawn. It's a diagram of a sentence of Joyce Carol Oats: "We learned to 'diagram' sentences with the solemn precision of scientists articulating chemical equations." (Florey 2006, p. 97).
By my count, there are two separate mistakes here, or perhaps one mistake and one highly unlikely interpretation of constituency. Can you spot them? I'll post my answers later.