Does a treant animate one or two trees with a single cast of its Animate Trees spell-like ability?

Question

For convenience, here is the full text of the ability in question:

Animate Trees (Sp) A treant can animate any trees within 180 feet at will, controlling up to two trees at a time. It takes 1 full round for a tree to uproot itself, after which it moves at a speed of 10 feet and fights as a treant (although it has only one slam attack and lacks the treant’s animation and rockthrowing abilities), gaining the treant’s vulnerability to fire. If the treant that animated it terminates the animation, moves out of range, or is incapacitated, the tree immediately takes root wherever it is and returns to its normal state.

Here's my understanding of the procedure:

1. As the ability is a spell-like ability with no specified action, the treant spends a standard action which provokes attacks of opportunity (but can cast defensively) to activate the ability.
2. The treant selects either one or two (this is the crux of my question) trees within 180 ft.
3. If it would not result in the having more than two trees animated and under its control at once, the selected tree(s) animates.
4. One full round later (not an action on the treant's part), the tree uproots and can begin taking actions as directed by the treant.

Since the ability does not say "can animate a tree ... at will", but "can animate any trees ... at will", does that mean it can choose any number of trees as long as it does not exceed its control limit?

Answer 1

It’s not clear

If we look at the description of the ability, your argument seems valid. The plural form suggests that a treant can animate two trees at a time. At the same time it leaves space for interpretation. Unfortunately, I haven’t found any confirmation in Pathfinder rulebooks.

But.

We all know that Paizo used plenty of material from D&D 3.5 without significant change. Here is the treant Animate Trees special ability from D&D 3.5:

Animate Trees (Sp)

A treant can animate trees within 180 feet at will, controlling up to two trees at a time. It takes 1 full round for a normal tree to uproot itself. Thereafter it moves at a speed of 10 feet and fights as a treant in all respects. Animated trees lose their ability to move if the treant that animated them is incapacitated or moves out of range. The ability is otherwise similar to liveoak (caster level 12th). Animated trees have the same vulnerability to fire that a treant has.

It references the liveoak spell which reads (emphasis mine):

Liveoak

Target: Tree touched

This spell turns an oak tree into a protector or guardian. The spell can be cast on only a single tree at a time; while liveoak is in effect, you can’t cast it again on another tree. The tree on which the spell is cast must be within 10 feet of your dwelling place, within a place sacred to you, or within 300 feet of something that you wish to guard or protect. [...]

It looks like in D&D 3.5 a treant can animate only one tree at a time.

The Pathfinder description lacks the reference to the liveoak spell even though the liveoak spell with a similar description exists in Pathfinder. Unfortunately, we don’t know whether the reference was removed because the Animate Trees special ability was supposed to work differently, including the number of trees animated at a time, or for some other reason.

I, personally, would go for one tree at a time, because I think that Paizo could’ve spelled it out more clearly, if they wanted to change the ability, so I’m inclined to think that it’s an overlook on Paizo’s side. But I don’t have solid evidence for that.

Answer 2

The ability is unclear because the English word any has two meanings:

1. used to refer to one or some of a thing or number of things, no matter how much or how many.
2. used to express a lack of restriction in selecting one of a specified class.

(Source: Google search, powered by Oxford Languages)

So, any tree might mean the single tree you choose among those available or a certain number of trees chosen among those available, potentially even every single tree available if you so choose.

My first reading would be that the treant chooses any number of frees within 18o-ft. and animates them all, and two of them (of the treant's choice) are under his control, while all others are free-willed. Or maybe that during every of the treant's turns, it can control two of those.

Since the ability is a whole mess, we must think about what would be balanced and extrapolate from other sources, like Ols did in their very good answer. But we will never know how that was supposed to work unless the authors tell us.