STUART WILSON / SCIENCE PHOTO LIBRARY STUART WILSON / SCIENCE PHOTO LIBRARY
Sahara Mustard (Brassica tournefortii) is an invasive weed that is transforming the southwestern United States. It is a robust, fast-growing, drought-tolerant winter annual that prefers sandy soils. Large plants can produce up to 16,000 seeds. Dried plants break off at the base and tumble like Russian thistle (tumbleweed). The seeds out-compete native annuals, choking them out and when dry, creating large swaths of flammable tinder. Brushfires from lightning strikes spread widely, killing the vulnerable desert flora which is not fire tolerant. Eradication or control of this weed presents many challenges and success appears doubtful. This invader probably arrived in North America as a contaminant in crop seed. The first record is from California's Coachella Valley in 1927. Photograph taken in Joshua Tree National Park.
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