brent wrote:
I read on a website that hardwood will expand (swell) across the width
of the strip, but not end to end and therefore you dont need a gap
between the wall and the ends of the hardwood strips.Is this true?

I cannot give you an exact answer but it will expand in both
directions. Wood is an anisotropic material, i.e. properties are
different in different directions because or orientation.
To see this phenomenon, take a piece square piece of paper, measure it
and soak it and remeasure.
Frank