So basically, I'm having a bit of trouble when it comes to introducing things to a story that are a bit "far out" in terms of normality. For example, lets say I was writing a story where people could turn into trees. How would I introduce that to the story? Would I just describe someone transforming into a plant and hope the reader gets it? Would I stage a conversation as infodump? This is a problem I've been having for a bit of time. Thanks for any input.
Maybe there's another character nearby who as the tree-ification goes on realises the other person is becoming a tree? And either comments, thinks on it, or there's some narration along the lines of "and Joe realised they were turning into trees"
As to not distance the reader from the novel by explaining it (thus drawing them out of the story), just introduce it like an normal everyday occurrence. For example, saying something like "Everyone can turn into trees. This happens everyday." is just awkward, and too much TELLING. Here's an example of what I think would be not only smoother, but also kind of cool: "Jeff looked at Frank. They had been friends long enough that Jeff could recognize Frank in his tree form. Frank's branches were thin and brittle, and his leaves were scarce. All of a sudden, Frank shifted back to his human form."
How you introduce these elements into the story depends on 1. how normal they are (is it common/expected for people to turn into trees?) and 2. if there's anyone around who considers the occurrence NOT normal (that's an instance where it's acceptable to explain a weird situation to somebody in dialogue, though you still have to look out for "infodumping"). The more common or normal an occurrence is in the world you're writing, the less time you're going to spend on explaining it, and should just show it. The reader will assume, by the lack of surprised reaction from other characters, that this must be normal. (Just stay consistent to the rules of your world.) If the occurrence is NOT normal, you can still use the reactions of other characters to convey this--"Oh my God! Mary, come here! John just turned into a tree!! What the--??" Not exactly those words, but you get the idea.
^ Everyone has a better idea then I do. But here I go anyway, trying to make a more impressive answer then what has just been started, how about the voice of the trees. Write it out as if they are already a tree and then instead of having a long reason why they transform, just kind of state its a normal thing. An example might be better, I am tree right now, but in a few minutes I'm going to be human again. Trust me is perfectly normal, everyone can transform into trees. Or something along the lines. My answer isn't as constructive as I thought. Well take what you want from what I wrote, like you can. Here and Now ~Rem Nightfall
Just let it happen and allow your characters to respond accordingly. The ones who know what's going on can explain it to the ones who don't, but try not to go into too much detail if you don't have to. The key is to not dwell on it too much, because then it starts to seem like a gimmick or something thrown in just to up the weirdness factor.