[Lebowski]

Actually, there is current debate over the use of the term Sativa.

I don't have their source, but the collective I visit actively looks at research and information about marijuana, to pass the knowledge onto their patients.
They maintain, based on readings they did (which i'll try to aquire) that Cannabis Sativa refers to industrial grade hemp, the tall, stalky stuff with around 1% THC content.
The proper definitions are:
-Cannabis Indica for what we consider "sativa" strains
-And Cannabis Afghanica, a geographically derived name, for what we consider indica

This sounds far fetched at first, and is hard to digest (i still call em sativa and indica to avoid confusion). Take the information with a grain of salt, and i'll try to get back here with their sources.

Also, I believe the term sativa started getting tossed around and misused around the time prohibition started, ~1930. There was the whole confusion of hemp vs. marijuana going on then.