Level BAB Fort Ref Will Special Spells per Day/Spells Known
1st +1 +1 +0 +1 Create Infusion +1 level of existing class
2nd +2 +1 +1 +1 Sun sustenance, Verdant Wisdom +1 level of existing class
3rd +3 +2 +1 +2 Verdant Aid +1 level of existing class
4th +4 +2 +1 +2 Plant Sagacity +1 level of existing class
5th +5 +3 +2 +3 Grovebound Form +1 level of existing class
6th +6 +3 +2 +3 Treant wild shape +1 level of existing class
7th +7 +4 +2 +4 — +1 level of existing class
8th +8 +4 +3 +4 Animate tree +1 level of existing class
9th +9 +5 +3 +5 — +1 level of existing class
10th +10 +5 +3 +5 Gaea's embrace +1 level of existing class
Requirements
Alignment: Any non-evil
Skills: Knowledge Nature (7)
Feats: Skill Focus (Knowledge: Nature)
Special: Green Empathy class feature, plant domain.
Spells: Able to cast command plants.
Hit die
d8
Skill points
4 + Int
Class Features
Weapon and Armor Proficiency: Verdant lords gain no weapon or armor proficiencies.
Spells per Day/Spells Known: At each verdant lord level, the character gains new spells per day (and spells known, if applicable) as if he had also gained a level in a spellcasting class to which he belonged before adding the prestige class. He does not, however, gain any other benefit a character of that class would have gained unless it is Channeling or Wild Shape, in which case the progression continues as normal. If the character had more than one spellcasting class before becoming a verdant lord, the player must decide to which class to add each verdant lord level for determining spells per day and spells known and Channeling/Wild Shape.
Create Infusion(Su): At 1st level, the verdant lord may infuse one spell of any level he is able to cast into a plant object once per day. Infusing a plant takes an entire day of casting and requires a plant or herb costing a price equal to the spell-level x 50 gp.
Verdant Wisdom(Ex): At 2nd level, the Verdant Lord gains a bonus equal to his class level on all Knowledge (Nature) and double that on Wild Empathy checks related to plants, including the use of this skill to forage for herbs.
Sun Sustenance (Ex):At 2nd level, the verdant lord gains the ability to draw energy from the sun. As long as he spends at least 4 hours of the day outdoors, he can draw sustenance from the sun itself, and thus he requires no food that day. He still thirsts, however, and needs the standard amount of water to survive.
Verdant Aid(Su): Beginning at 3rd level, the verdant lord can channel stored spell energy into certain healing spells that he hasn't prepared ahead of time. This works like the cleric's spontaneous casting ability. He can "lose" a prepared spell to cast any cure or heal spell of the same level or lower (Using the cleric/oracle spell levels.). For example, a verdant lord who has prepared faerie fire (a 1st-level spell) may lose that spell to cast cure light wounds (also a 1st-level spell) instead. Any character affected by the Verdant Lord's Cure or Heal spells also gain fast healing equal to twice the spell's level for 10 + caster level rounds.
The Verdant Lord may channel positive energy as a cleric, counting his Verdant Lord levels to determine the character's ability to channel energy. (If you're using my Natural Channeling variant, then switch the cleric bit with druid.)
Plant Sagacity(Ex): At 4th level, the Verdant Lord can control 3 more HD worth of plants. This bonus increases to 6 at 8th level. In addition, the Verdant Lord gains Treespeach (Ex), able to use his Diplomacy skill as a bonus to his Wild Empathy checks.
Grovebound Form (Su): At 5th level, the Verdant Lord is able to turn into a Treant as per his Wild Shape class feature. In addition, any other form the druid may possess gains the Plant sub-type.
If the Verdant Lord does not have the Wild Shape class feature, then the Verdant Lord may take the form of a treant and back again once per day. This ability otherwise works like wild shape. Since a treant has a voice and manipulative appendages, the verdant lord can cast spells normally while in treant wild shape.
Animate Tree (Sp): At 8th level, a verdant lord can animate a tree within 180 feet of him once per day. It takes a full round for a tree to uproot itself; thereafter it has a speed of 30 feet and fights as a treant with respect to attacks and damage. The animated tree gains a number of bonus Hit Dice equal to the number of verdant lord levels the character possesses. Though its Intelligence score is only 2 while animated, the tree automatically understands the verdant lord's commands. The character can return the animated tree to its normal state at will, and it automatically returns to its normal state if it dies or if the verdant lord who animated it is incapacitated or moves out of range. Once the tree returns to its normal state by any means, the verdant lord cannot animate another tree for 24 hours.
Gaea's Embrace(Su): At 10th level, the verdant lord permanently becomes a plant creature, though all forms of wild shape that the character could previously use remain available to him. His type changes to plant, he gains a passive fast healing 5, low-light vision, is immune to poison, sleep, paralysis, stunning, and polymorphing, and is not subject to critical hits or mind-influencing effects (charms, compulsions, phantasms, patterns, or morale effects). He no longer suffers penalties for aging and cannot be magically aged. Any aging penalties he may already have suffered, however, remain in place. Bonuses still accrue, and the verdant lord still dies of old age when his time is up.
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This was actually much harder than I anticipated. I'm going to rely on those reading to give me some solid criticism in terms of both balance and flavor.