How do you know from looking at a tree in the winter if it is a softwood or a hardwood?

There are books that show the grain patterns of different woods. If you can match the grain pattern of the wood you're looking at to a wood in the book, you can figure out what you have. The relative softness of the wood isn't a way to tell; some hardwoods are softer than some softwoods. Example: radiata pine and poplar. Poplar's softer than radiata pine, but radiata pine is a "softwood" because it comes from a needle-leaf tree.