Bestiary 3 is awesome and well I can see someone in my gaming group playing a Leshy. The Leaf Leshy looks to be the most appropriate with the CR in mind. The new Thundercats show features these little plant-men in one of the episodes. Here is a rough idea of what I'm thinking.
Leshy, Leaf
This little plant person is clad in a winglike leak cloak and pinecone armor, wielding a twig as a makeshift spear.
–4 Strength, +2 Dexterity, -2 Intelligence, +2 Wisdom: Leshys are fast and observant, but relatively weak and slow-witted.
Small: Leshy's are Small and gain a +1 size bonus to their AC, a +1 size bonus on attack rolls, a –1 penalty to their CMB and CMD, and a +4 size bonus on Stealth checks.
Darkvision: Leshy can see in the dark up to 60 feet.
Fly: Leshys have a fly speed of 10 feet (clumsy); glide
Glide (EX) A leaf leshy cannot use its fly speed to hover. When flying, a leaf leshy must end its movement at least 5 feet lower in elevation that it started.
Keen Senses: Leshys receive a +2 racial bonus on Perception skill checks.
Low-Light Vision: In dim light, leshys can see twice as far as humans.
Natural Climber: Leshys can climb at a rate of 10 feet.
Natural Immunities: Electricity and sonic.
Plant Traits (EX) Immune to all mind-affecting effects (charms, compulsions, morale effects, patterns, and phantasms), paralysis, poison, polymorph, sleep and stun.
Seedpods (EX) Leaf leshy sprout explosive acorns, pine cones, or other seedpods, and can hurl these as ranged attacks, A seedpod has a range increment of 10 feet and detonates on contact to deal 1 point of bludgeoning damage (this damage is not modified by Strength). Anyone struck by a seedpod must succeed at a DC 11 Fortitude save or be deafened for 1 round. The save DC is Constitution-based.
Self-Perservation: Leshy have an inate desire to stay alive and receive a +2 racial bonus on Survival checks.
Slow Speed: Leshys have a base speed of 20 feet.
Spell-like Abilities: (CL 2nd;concentration +3)
Constant-pass without trace
SQ change shape (Small tree; tree shape), verdant burst.
Languages: Leshys begin play speaking Druidic, Sylvan, and plantspeech (trees). Leshys with high Intelligence scores can choose from the following: Common, Elven, and Gnome.