Different textbooks present different variations on the tree diagram, depending on the details of their analysis. The basic principles, however, remain constant, and if you understand them, you should be able to grasp the diagrams' essence no matter what the details. Tree diagrams are most often drawn above the item being diagrammed.[1] A tree consists of nodes. A node has a label, for example NP for noun phrase, VP for verb phrase, and so on.

Q. Please explain how to diagram a sentence.
A. First spread the sentence out on a clean, flat surface, such as an ironing board. Then, using a sharp pencil or X-Acto knife, locate the 'predicate,' which indicates where the action has taken place and is usually located directly behind the gills. For example, in the sentence: 'LaMont never would of bit a forest ranger,' the action probably took place in a forest. Thus your diagram would be shaped like a little tree with branches sticking out of it to indicate the locations of the various particles of speech, such as your gerunds, proverbs, adjutants, etc.

The constituent that we will see most is the phrase. A phrase consists of a single main word, called the head of the phrase, and other words that modify or give grammatical information about the head. These other words in the phrase are called the phrase's attributes. Informally, we might say that the head word is the main idea of the phrase.

(2) Russia's proposal at the conference

The phrase in example (2) is talking about a kind of proposal. Russia's and at the conference tell us what specific proposal we're talking about. Proposal, therefore is the head word.[1]

Diagrams of the Principal Parts of Simple, Compound, and Complex Sentences.

SIMPLE SENTENCES.

Intransitive—having one Subject, one Predicate.
Transitive—having one Subject, one Predicate, one Object.

“Time slept on flowers and lent his glass to hope.”

(25.)

A mixed sentence.—Def. 30, b.

“Too low they build, who build beneath the stars.” Young

(21.)

A complex sentence—both simple and intransitive.

At the end of Harvey's Revised English Grammar (1878) is a system which looks similar to R-K diagrams, but which is greatly simplified, in what appears to be unfortunate ways. Visually, note the absence of R-K's slanting lines for modifiers. Also, notice that the various modifiers are, in many cases, not clearly separated.

Sample diagrams for complex sentences, showing content clauses, infinitives, etc. (pp. 268-269)

The last page of this volume contains a plug for another book of diagrams by the same publisher: Irish's Grammar and Analysis Made Easy and Attractive by Diagrams. Given the nature of the diagrams in Harvey's Grammar, I suspect that this diagram system was cribbed from Reed and Kellogg, with enough changes to avoid copyright problems.

1. “In the beginning God created the heaven and the earth.”

(14.)

1. “The king of shadows loves a shining mark.”

(13.)