Plant Profile: Pentanema britannicum

Inula, a member of the Asteraceae family, is a relatively new arrival in North America. Originally from Europe, this creeping perennial weed has made its way into various nurseries through contaminated hostas and daylilies imported from the Netherlands. Once established, Inula spreads vigorously through thick, fleshy roots that generate new shoots. The plants develop rosettes of elongated, slender leaves that bear a resemblance to certain asters or fleabanes. While the leaves may also look similar to those of buckhorn plantain, they differ in that plantain leaves feature five distinct parallel veins, whereas Inula leaves have a net-like vein pattern. The leaves measure between 3 to 10 inches in length and about 1/2 to 1 inch in width, remaining green throughout the winter months. For flowering to occur, the plants require a chilling period. In spring, they spread quickly, and by early to mid-summer, flowering stems start to grow taller. The flowers, which are typically aster-like, bloom in shades of yellow to light orange. It remains uncertain whether this species produces viable seeds in North America. Since Inula primarily reproduces vegetatively, commonly used preemergence herbicides are ineffective against it. Completely removing all root fragments of Inula is nearly impossible; therefore, if a container plant becomes infested, it is advisable to destroy it to prevent further spread of the weed.