Marijuana is also known as Cannabis. Cannabis is the genus, and what comes after is the selection of the three main classes of Marijuana. We have Cannabis Sativa, Cannabis Indica, and Cannabis Ruderalis.
If you live in the Western Hemisphere, the majority of your Marijuana is Sativa, or Indica/Sativa hybrids.
If you live in the Easter Hemisphere, the majority of your Marijuana is Indica, and Indica/Ruderalis.
Most people will DENY that Ruderalis exists, and are too thick-skulled to believe there is another class of Marijuana, that is because the term "weed" is derived from Ruderalis. Cannabis Ruderalis has a much lower THC percentage than Cannabis Indica/Sativa, but when bred as a Hybrid with Cannabis Indica, it yields higher THC percentages than Sativa!
Most people don't hear of Ruderalis because of its low THC content. The only way to get high from this plant is to basically grow it with nitrogen enriched fertilizer, keeping the ph balance perfect, and then smoking an ounce of it to your face. Other than that it's useless, unless made hybrid with Indica. I'm doing some more research on it right now, I'll let you guys know if I find anything interesting we can do with it. So far I've found it has higher traces of multiple cannabinoids I haven't even found in Indica/Setiva, I may possibly have a good recipe or two from this
P.S., the reason Ruderalis termed Marijuana "weed" is because it literally grows like a weed. It will grow anywhere, under any condition, in almost any climate, and spreads out like a BITCH!