Tough Little Ruellia humilis
Story & Photos by Edie Starbuck
When it is dry as a bone and all the plants seem to be struggling to stay alive, let alone bloom, Ruellia humilis, Hairy Wild Petunia, can still be counted on to give a good show. Get out in the mornings and you can see multiple one inch diameter, tubular, lavender blooms often scattered throughout your yard. Though they can be aggressive enough that they are often considered weedy, they are Missouri natives and worthy of our respect.
Despite its common name Ruellia humilis is not closely related to the domestic petunia. Ruellia humilis is a member of the family Acanthaceae, not Solanaceae as is the domestic petunia.
Long-tongued bees, short-tongued bees and Syrphid flies visit the flowers for nectar (Minnesota DNR, Ruellia humilis : Wild Petunia | Rare Species Guide | Minnesota DNR (state.mn.us)). It is the larval host plant for the common Buckeye butterfly (University of Michigan, Native Plant of the Week: Wild Petunia | Matthaei Botanical Gardens and Nichols Arboretum (umich.edu)).
The plants bloom from May to October and are at their peak about now (mid-July). Ruellia humilis is a mighty and prolific bloomer, with flowers blooming along the stem in succession, but each flower only lasts one day and on a hot day the blossoms fade quickly so try to get out to appreciate these tough little beauties early in the day.