Russian thistle (Salsola tragus L.) belongs to the goosefoot (Chenopodiaceae) family. Another weed species in this family is kochia (Bassia scoparia L.). Both of them are often called “tumbleweeds” and are commonly seen in the western U.S. When a plant matures, it dries up and the stem breaks off at the base, becoming a tumbleweed. The seeds disperse as the plant tumbles with the wind.
Russian thistle is a native of Russia and was introduced to the U.S. through contaminated flax seed in the late 1800s. Now it is found in every state in the U.S., except Alaska and Florida. It is a summer annual weed species.
The seedlings look like grass seedlings when they first emerge, and later look similar to pine needles. The young leaves of Russian thistle are small, narrow, dark-green in color, and the older leaves have stiff spines with a sharp, pointed tip. The flowers are small and petal-less, located in the leaf axils between a pair of spiny bracts. The stems are erect with many branches, and often shown reddish or purple striping. The mature plants are woody and can grow up to 4 ft tall. The matured Russian thistle plants provide cover for pheasants. Its seeds and foliage can be food sources for small mammals and songbirds. However, they are toxic to cattle and sheep due to the nitrate level and oxalates, as well as the spike-like inflorescence. Only the young plants could be used as forage.
Russian thistle has a taproot system and is extremely drought tolerant. The taproot can grow several feet into the soil for moisture. It is well adapted for desert-like environments and is very competitive when moisture is a limiting factor. A Russian thistle plant can produce more than 200,000 seeds, yet the seeds can lose viability quickly in the soil. The seeds usually use the winter moisture to germinate in late winter or early spring. Normally more than 90% of seeds germinate or decay within the first year.