Plant of the Week: Sweet Flag

This plant of the week is pretty sweet…it is sweet flag “Acorus americanus"! 

As its name implies, sweet flag has a distinctively sweet citrus or licorice smell. The long grass-like leaves droop outwards and can reach lengths of 2 – 6 feet. Sweet flags seeds can be difficult to germinate, but when established, can become a dense sweet-smelling clonal clump. The fruit resembles a small green banana growing directly off the leaf.  

The subject of ongoing study, sweet flag is the sole surviving member of its genus and part of the oldest surviving line of monocots! This means it's not closely related to any other plants.  

Much of the ongoing research into sweet flag focuses on historical descriptions and modern genetics. The range for the native North American sweet flag stretches ocean to ocean, north to Canada and south all the way down to Virginia.  Ancient cultivation seems to have produced several sterile varieties that can only reproduce vegetatively (through their roots) and have become naturalized in Europe and South Asia. Intriguingly, these sterile varieties produce toxic compounds that were historically used as medicine. As a result, all sweet flag, including the non-toxic native variety, is banned in the US as a food or medicine ingredient.  

This sweet, sole surviving species is a great native choice to fill along shorelines, ditches and rain garden basins.  

Written by Brandon Canaie