In this document of the grass, the branch(es) and the vine, it will show you that these are keyes that refer to either a person or people, so that when you read these words in a different place in the Bible, you can apply them, and help you figure out what the Lord is referring to. Many places in the Bible, people are referred to as different things, including trees, fruit, and stubble to name a few.
All text taken from the King James Bible
Is.40:6-7 - The voice said, Cry, And he said, What shall I cry? All flesh is grass, and all the goodliness thereof is as the flower of the field: (7) The grass withereth, the flower fadeth: because the spirit of the Lord bloweth upon it: surely the people is grass.
Is.51:12 - I, even I, am he that comforteth you: who art thou, that thou shouldest be aftraid of a man [that] shall die, and the son of man [which] shall be made as grass:
I Peter 1:24 - For all flesh is as grass, and all the glory of man as the flower of grass. The grass withereth, and the flower thereof falleth away.
Is.4:2 - In that day shall the branch of the Lord be beautiful and florious, and the fruit of the earth shall be excellent and comely for them that are escaped Israel.
Is.11:1 - And there shall come forth a rod out of the stem of Jesse, and a Branch shall grow out of his roots:
Because the first letter of the word Branch is capitalized, this is referring to Jesus. Also, see - The Root or Stem of Jesse--A Righteous Branch/Holy One
Is.25:5 - Thou shalt bring down the noise of strangers, as the heat in a dry place; even as the heat with the shadow of a cloud: the branch of the terrible ones shall be brought low.
REMEMBER: The terrible ones is just another name for the devil, Satan, wicked one, son of perdition, etc., and his followers. So in this case it is those who are not following the Lord and his ways. See - Parable of the Kingdom and the Sower Scriptual Definitions
Jer.23:5 - Behold, the days come, saith the LORD, that I will raise unto David a righteous Branch, and a King shall reign and prosper, and shall execute judgment and justice in the earth.
A righteous Branch, and a King shall reign and prosper, and execute judgment and justice in the earth - these all refer to Jesus. There is no other person in the Bible referred to as, righteous, King and that can execute judgment
Zec.6:12 - And speak unto him, saying, Thus speaketh the LORD of hosts, saying, Behold the man whose name is The BRANCH; and he shall grow up out of his place, and he shall build the temple of the LORD: See - Temple(s) of God.
As stated earlier, we know that The BRANCH because it is capitalized this is referring to Jesus, and because he shall build the temple of the LORD: we know that our bodies are temples John 2:19 - Jesus answered and said unto them, Destroy this temple, and in three days I will raise it up. John 2:21 - ...he spake of the temple of his body.
Mal.4:1 - FOR, behold, the day cometh, that shall burn as an oven; and all the proud, yea, and all that do wickedly, shall be stubble: and the day that cometh shall burn them up, saith the LORD of hosts, that it shall leave them neither root nor branch.
In the above verse, it says that the day cometh that shall burn as an oven, and all the proud and those that do wickedly, or not follow God, shall be stubble, and the day that cometh shall burn them up, and there will neither be root nor branch - so a fire will come and burn up those that are not following God and his laws, and he (Jesus) will not leave any remanent (root or branch) behind that to not follow God. See - The Lord As Fire - to be type soon. There are many references in the Bible that refer to Jesus as being an unquenchable fire and will burn all that do not follow the Lord's ways.
John 15:2 - Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it that it may bring forth more fruit. See - The True Vine
John 15:4-5 - Abide in me, (Jesus) and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abode in me. (5) I (Jesus) am the vine, [are] the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing.
Rom.11:6 - For if the firstfruit be holy, the lump is also holy: and if the root be holy, so are the branches.
The root is referring to Jesus.
Rom.11:21 - For if God spared not the natural branches, take heed lest he also spare not thee.
If God allowed his only son to be crucified, then do you think he will spare you if you are not following his commandments? See - The Ten CommandmentsTemples of God