My problem is with the term 'mental'. Objects don't think, nor do humans all have the same thoughts about objects; and either of these possibilities is what "mental properties" makes me think of.
You ask what mental property allows us to distingish a pear tree from a cherry tree in the middle of winter? I have no idea. Whichever kind of tree it is, it isn't sending me clues by ESP. If I were asked how I could distingish a pear tree from a cherry tree in the middle of winter, I would say by the bark; possibly by size, shape, location, or seeds left on the ground (assuming no fruit was left hanging on the tree).