This isn't strictly a DM question, but I think it's close enough.
So my high elf wizard has gotten his hands on the root of a ''knifebush'' (basically the thorns are as big and dangerous as daggers), and he has been inspired by the twig blight to make his own variant, called a thornguard, he also wishes to create several variants, for example, ironwood and darkwood thornguards, as well as vineguards (made from assassin vines).
What I want to know is whether or not these creatures are viable (and correct CR) and could realistically be made by a high-level wizard, and if you have any ideas please submit them 
Thornguard
Medium plant, neutral good
Armor Class: 16 (13 natural +3 dexterity)
Hit Points: 19 (3d8 +6)
Speed: 30ft.
Ability Scores: Str 13. Dex 16. Con 14. Int 4. Wis 13. Cha 8.
Saves: Dexterity +5, Wisdom +3
Skills: Nature -1, Perception +3, Stealth +5
Damage Vulnerability: Fire
Damage Resistance: Bludgeoning and Piercing unless magical
Condition Immunities: Charmed, Blinded, Poisoned
Senses: Tremorsense 60ft. Passive Perception 13
Languages: Common, Elf, Sylvan
Challenge: 2 (450 EXP)
Wooden Body: When using stealth among trees the thornguard has advantage on its stealth rolls
Part of Nature: Gains no penalties from moving in naturally difficult terrain
Hivemind: Because of their connection to each other all thornguards have advantage on all wisdom saves and if a thornguard that is unflannked can see a thornguard that is, the flanked thornguard is unflanked
Thorned Body: Every round spent grappling the thornguard deals 1d4 +3 automatic piercing damage
Pointed Reflexes: The thornguard can use its reaction to make a rake attack against anyone who makes a melee attack against it
Actions:
Rake: +5 to hit. 1d6 +3 slashing damage
Launch Dart: +5 to hit 1d4 +3 piercing damage
Plant Thornseed: The thornguard can plant a thornseed that will over 4 months grow into a fully mature Thornguard, it can only grow one seed at the same time
Spell-Like Abilities: Ensnaring Strike (1st) level and Entangle (1st) 1/rest. Wisdom is used as the spellcasting modifier for these abilities
Thornguards are living constructs made out of knifebush that were created by the wizard Elandrieln Faeliun, they are all connected through a magical hivemind, and are connected to Elandriel in this way too
Ironwood Thornguard
Medium plant, neutral good
Armor Class: 17 (16 natural +1 dexterity)
Hit Points: 45 (5d10 +18)
Speed: 30ft.
Ability Scores: Str 17. Dex 12. Con 17. Int 5. Wis 12. Cha 8.
Saves: Strength, Constitution, Wisdom
Skills: Athletics +5, Intimidation +1, Nature -1, Perception +3
Damage Immunity: Bludgeoning and Piercing unless adamantine or magical
Damage Resistance: Bludgeoning, Piercing and poison. Slashing unless adamantine or magical
Condition Immunities: Charmed, Blinded, Poisoned
Senses: Tremorsense 60ft. Passive Perception 13
Languages: Common, Elf, Sylvan
Challenge: 3 (700 EXP)
Wooden Body: When using stealth among trees the ironwood thornguard has advantage on its stealth rolls
Part of Nature: Gains no penalties from moving in naturally difficult terrain
Hivemind: Because of their connection to each other all thornguards have advantage on all wisdom saves and if a thornguard that is unflannked can see a thornguard that is, the flanked thornguard is unflanked
Thorned Body: Every round spent grappling the ironwood thornguard deals 1d6 +3 automatic piercing damage
Pointed Reflexes: The ironwood thornguard can use its reaction to make a slam attack against anyone who makes a melee attack against it
Actions:
Multiattack: Can either slam twice or launch two darts per attack action
Slam: +5 to hit. 2d4 +3 bludgeoning
Launch Dart: +5 to hit. 1d6 +3 piercing damage
Plant Ironseed: The ironwood thornguard can plant a thornseed that will over 6 months grow into a fully mature Ironwood thornguard, the thornguard can only have one seed maturing at any one time
Spell-Like Abilities: Ensnaring strike (1st), Entangle (1st) and Hail of Thorns (1st) 2/rest. Spike Growth (2nd) 1/day
The ironwood thornguard was created by transmuting regular knifebush into ironwood, but in such a way that the bush was otherwise unaltered and unharmed
Darkwood Thornguard
medium plant, neutral good
Armor Class: 16 (14 natural + 2 dexterity)
Hit Points: 45 (7d8 +14)
Speed: 35ft.
Ability Scores: Str 13. Dex 15. Con 14. Int 12. Wis 17. Cha 10
Saves: Dexterity +4, Intelligence, +3 Wisdom +5
Skills: Arcana +3, Nature +3, Perception +5, Religion +3, Stealth +4
Damage Immunity: Bludgeoning and Piercing unless cold iron
Damage Resistance: Bludgeoning, piercing unless cold iron
Condition Immunity: Charmed, Blinded, Poisoned
Senses: Tremorsense 60ft. Passive Perception 15
Languages: Common, Elf, Primordial, Sylvan
Challange: 4 (1.100 EXP)
Wooden Body: When using stealth among trees the darkwood thornguard has advantage on its stealth rolls
Part of Nature: Gains no penalties from moving in naturally difficult terrain
Hivemind: Because of their connection to each other all thornguards have advantage on all wisdom saves and if a thornguard that is unflannked can see a thornguard that is, the flanked thornguard is unflanked
Thorned Body: Every round spent grappling the darkwood thornguard deals 1d6 +2 automatic piercing damage
Pointed Reflexes: The darkwood thornguard can use its reaction to make a rake attack against anyone who makes a melee attack against it
Actions:
Multiattack: Either makes two rakes or launches two darts per attack action
Rake: +4 to hit. 2d4 +2 slashing damage and a DC 12 poison, saving for half damage against 4d6 damage
Launch Dart: +4 to hit. 1d6 +2 piercing damage and a DC 12 poison, saving for half damage against 4d6 poison damage
Plant Darkseed: The darkwood thornguard can plant a thornseed that will over 8 months grow into a fully mature Darkwood Thornguard, but the darkwood thornguard can only have one seed growing at the same time
Spell-Like Abilities:
Druidcraft, Guidance, Mending, Poison Spray (2nd), Produce Flame (2nd) and Thorn Whip (2nd) At Will
Animal Friendship, Farie Fire, Speak With Animals, Speak With Plants Animal Messanger, Create or Destroy Water, Locate Animals and Plants, Purify Food and Water, Ensnaring Strike (2nd), Entangle (2nd), Spike Growth (2nd), Cure Wounds (2nd), Healing Word (2nd) 3/rest.
Heat Metal (2nd), Melf’s Acid Arrow (2nd) 2/rest.
Conjure Animals 1/day
Plant Growth 1/week
The ability used for casting is wisdom, and there is no need for concentration on any of the spells except for Conjure Animals
Darkwood thornguards are the most powerful version of thornguards, this is because even though they are made much like ironwood thornguards, they are also heavily infused with magical essences, this is only possible because of darkwood’s natural susceptibility to magical energies
Vineguard
medium plant, neutral
Armor Class: 13 (11 natural +2 dexterity)
Hit Points: 16 (3d8 +3)
Speed: 30ft. ground and 30 ft. climbing
Ability Scores: Str 15. Dex 14. Con 13. Int 4. Wis 11. Cha 8.
Saves: Strength, Dexterity
Skills; Sneak +6, Nature -1, Perception +2
Damage Vulnerabilities: Fire, slashing
Damage Resistance: Bludgeoning. Piercing Unless cold iron
Condition Immunities; Charmed, Blinded, Poisoned
Senses: Tremorsense 60ft. Passive Perception 12
Languages: Common, Elf, Sylvan
Challange: 1 (200 EXP)
Wooden Body: When using stealth among trees the thornguard has advantage on its stealth rolls
Part of Nature: Gains no penalties from moving in naturally difficult terrain
Hivemind: Because of their connection to each other all thornguards have advantage on all wisdom saves and if a thornguard that is unflannked can see a thornguard that is, the flanked thornguard is unflanked
Unfurling Structure: The vineguard counts as large-sized when grappling. The vineguard can also pass through any space as small as one inch at 2 feet per foot movement
Thorned Choking Vines: Every round spent grappling the vineguard deals 1d4 +2 automatic piercing damage and 1d4 +2 automatic bludgeoning damage
Improved Grappling: When grappling, the vineguard can make a slam attack with his bonus action, this attack may only target the other grappler
Actions;
Slam: +4 to hit (reach). 1d6 +2 bludgeoning damage
Plant Vineseed: Plants a thornseed that over 4 months grow into a fully mature vineguard, the vineguard can only have one seed growing at any one time
Spell-Like Abilities: Thorn Whip (1st) At Will
Vineguards are made much like thornguards, except assassin vines are used instead of knifebush
Thornlord
large plant, neutral good
Armor Class: 19 (18 natural +1 dexterity
Hit Points: 95 (10d12 +30)
Speed: 40ft.
Ability Scores: Str 21. Dex 12. Con 16. Int 15. Wis 14. Cha 13.
Saves: Strength +7, Constitution +5, Wisdom +4
Skills: Arcana +4, Athletics +7, History +4, Investigation +4, Insight +4, Nature +4, Perception +4, Religion +4
Damage Immunities: Bludgeoning, Piercing and Poison
Damage Resistance: Slashing unless cold iron and magical
Condition Immunities: Charmed, Blinded, Poisoned
Senses: Tremorsense 120ft. Passive Perception 14
Languages: Common, Elf, Sylvan, Primordial, Draconian
Challange: 9
Wooden Body: When using stealth among trees the thornlord has advantage on its stealth rolls
Part of Nature: Gains no penalties from moving in naturally difficult terrain
Hivemind: Because of their connection to each other all thornguards have advantage on all wisdom saves and if a thornguard that is unflannked can see a thornguard that is, the flanked thornguard is unflanked
Thorned Body: Every round spent grappling the thornlord deals 3d6 +5 automatic piercing damage
Wrath of Nature: In combat -or whenever the thornlord is angry-, everyone that is not a thornguard must succeed on a DC 15 wisdom save or be frightened of the thornlord for 1d4 +1 rounds. If you succeed on the save you are immune until either 24 hours have passed or you have taken a long rest
Actions:
Multiattack: Either three uses of the slam, rake and impale abilities in any combination, or use the throw spike and launch thorns abilities thrice in any combination
Slam: +7 to hit. 3d8 +5 blugeoning damage
Rake: +7 to hit. 3d8 +5 slashing damage
Impale: +7 to hit. 3d8 +5 Piercing damage
Throw Spike: +7 to hit. 3d6 +5 piercing damage
Launch Thorns; 15ft. cone DC 17 dexterity save for half damage, 2d8 +5 piercing damage
Plant Thornseed: The thornlord can plant any kind of thornseed he wishes, but he can only have two of each kind growing at the same time
Plant Lordseed: The thornlord can create a lordseed that can be planted into the mother tree of a forest, this seed will then grow into a thornlord in a process taking 4 years, it takes 10 years for a thornlord to create another seed
Spell-Like Abilities:
Druidcraft, Guidance, Mending, Poison Spray (3rd), Produce Flame (3rd)and Thorn Whip (3rd) At Will
Animal Friendship, Farie Fire, Speak With Animals, Speak With Plants Animal Messenger, Create or Destroy Water, Locate Animals and Plants, Purify Food and Water, Ensnaring Strike (3nd), Entangle, Spike Growth (3nd), Cure Wounds (3nd), Healing Word (3nd) 4/rest.
Heat Metal (3nd), Melf’s Acid Arrow (3rd) 3/rest.
Conjure Animals (2nd) 2/day
Plant Growth 1/day
The ability used for casting is wisdom, and there is no need for concentration on any of the spells except for Conjure Animals
The thornlord was created by Elandriel Faeliun by creating a lordseed and planting it into the mother tree of a forest, it took it 4 years to mature
Corrupted Thornguard
medium plant, neutral evil
Armor Class:
Hit Points: 52 (8d8 +16)
Speed: 30
Ability Score: Str 17. Dex 16. Con 14. Int 8, Wis 13. Cha 9.
Saves; Dexterity, Constitiution
Skills: Sneak +5, Perception +3
Damage Vulnerabilities: Radiant
Damage Immunities: Poison. Bludgeoning and piercing unless cold iron or magical
Damage Resistance: Bludgeoning, Piercing, Necrotic. Slashing unless cold iron or magical
Condition Immunities: Charmed, Blinded, Poisoned
Senses: Tremorsense 60ft. Passive Perception 13
Languages: Common, Elf, Sylvan
Challenge: 4
Wooden Body: When using stealth among trees the darkwood thornguard has advantage on its stealth rolls
Part of Nature: Gains no penalties from moving in naturally difficult terrain
Hivemind: Because of their connection to each other all thornguards have advantage on all wisdom saves and if a thornguard that is unflannked can see a thornguard that is, the flanked thornguard is unflanked
Thorned Body: Every round spent grappling the darkwood thornguard deals 1d6 +2 automatic piercing damage
Pointed Reflexes: The darkwood thornguard can use its reaction to make a rake attack against anyone who makes a melee attack against it
Actions:
Multiattack: Either two rake, slam or launch dart attacks per attack action
Slam: +5 to hit. 1d8 +3 bludgeoning damage
Rake: +5 to hit. 1d8 +3 slashing damage
Launch Dart: +5 to hit. 1d6 +3 piercing damage
Corrupt Thornguard: Touch a Darkwood thornguard and force him to make a DC 13 wisdom save or die instantaneously, the next day it will come alive again as a corrupted thornguard, if he succeeds he is immune for the next 24 hours
Spell-Like Abilities:
Poison Spray (2nd) , Thorn Whip (2nd) At Will
Entangle, Ensnaring Strike (2nd), Inflict Wounds (2nd) 2/rest
The darkwood thornguard is just a plot hook for my DM to use if he is so inclined (my wizard has a sample of flesh from the heart of a corrupted dryad).
And the thornlords are all connected to the wizard wich in turn connects him to the rest of the thornguards (essentially he is their king/god)
So? any ideas or pointers?
Anyone willing to help me?