create some objects, you can store information like that.
Code:
var plant //whatever plant is

var f1 = {};

f1.func = _root.tilePlant;
f1.args = [plant, 1, 11, _root.plant1[4]];

_root.a1[1] = f1;
then you can call the function like so:
Code:
_root.a1[1].func.apply(_root.a1[1].args, this);