Miley Cyrus -- Let's Be Blunt ... She's Smoking Weed, Right?

Miley Cyrus is blazin' a trail for millions of young women in America ... it's actually a trail of smoke that makes you really hazy and giggly.

She's not hiding it anymore ... no more, "It's not marijuana, it's Salvia." The smoke sesh went down Sunday night at Greystone Manor in Hollywood.

Greystone is turning into the go-to ganja joint ... Rihanna was toking a fat one a week earlier.

Liam and Miley have a lot in common ... except her hunger game ends with a bag of Cheetos.