
Rosemary is an aromatic evergreen herb with needle leaves and a resinous, piney scent.
The sprig is here to be smelled and to be looked at, so a substitute has to be something you can lay across a glass. Its resin is the part that shifts: another woody herb moves the aroma, and a syrup moves the sugar with it.
Dried rosemary
Concentrated and coarser, and it will not garnish. In a syrup it works at about a third of the fresh quantity; in a drink it floats and does not soften.
Rosemary syrup
The flavor already dissolved, which suits a shaken drink. What it cannot do is scent the glass on the way to the mouth, and that is most of what a sprig is for.
Wrapped and refrigerated it holds a couple of weeks, longer than a soft herb because the oil sits inside the needles, not on the leaf surface. It dries well and loses very little doing so, which is unusual for a herb.