A plant from Palaven, a rather common and dull wildflower to which ancient turians ascribed mystical properties. It was (and still is, in some places) used as an altar plant, and carrying a sprig around with you is supposed to bring good luck.
According to Lepantis Corvax:
"My mother used to teach biology by taking us circus children out to the nearest empty patch and giving a complete phytotomical explanation of every piece of vegetation we ran across. Verbanaium always featured prominently in these lessons, and nowadays that's whom I'm reminded of whenever I drive past a field of them."