Helminthotheca echioides
Image: Stemonitis
Description
Helminthotheca echioides may grow up to 90 cm (35 in) tall, with a thick, furrowed stem and spreading branches. The leaves are 10-20 cm (4-8 in) long, oblanceolate with a short petiole. The leaves, branches and stem are all covered in thick bristles. The inflorescences are 2-3.5 cm (0.8-1.4 in) wide and subtended by between 3 and 5 large ovate-cordate involucral bracts. These large bracts are the defining feature of the genus Helminthotheca.A number of infraspecific taxa are recognised, varying in their leaf shape.
Propagation instructions - seeds
Control can be achieved by hand pulling, string trimming, or hoeing when soil is moist. Roots should be removed to 2 inches below the soil surface. Mowing repeatedly will suppress plants, but basal leaves may result in some recovery. It is not known whether plants are palatable to livestock.
Burning may be an effective control option, but there are no studies to support this. However, bristly oxtongue often occurs in areas with annual grasses, and it is a late season plant. As such, there is likely a window of opportunity for burning after grasses have dried to provide fuel, but before bristly oxtongue has produced viable seed.
There are no biological control agents available for the control of bristly oxtongue.
(DiTomaso, J.M., G.B. Kyser et al. 2013. Weed Control in Natural Areas in the Western United States. Weed Research and Information Center, University of California. 544 pp)