Invasive Plant Removal
The entire Santa Monica Mountains NPS team was invited to participate in the removal of Russian Thistle a.k.a. Tumbleweed from the King Gillette Ranch Visitor Center in Calabasas. Here are some basic facts about the Salsola australis plant according to the Invasive Weed Field Guide of the Santa Monica Mountains National Recreation Area.
Annual to short-lived perennial herb, many-branched, round, bushy shape, 1 to 4 feet tall. Stems: usually red or purple striped. Leaves: Initially, long, string-like and soft. Mature leaves are short, scale-like, sharp pointed to spiny. Flowers: Inconspicuous, greenish, growing where the leaf branches off the stem. Plant dries into a ball that breaks off at the base and blows in the wind – forming the ubiquitous tumbleweed.
Blooms May to October. Seeds are dispersed in the fall when the dead plant breaks away and starts to roll.
Where does it grow?
Disturbed conditions: agricultural fields, vacant lots, roadside shoulders and ditches – thrives in salty and alkaline soils. There are thistle populations throughout the Santa Monica Mountains and Simi Hills, particularly along roads and disturbed grassland areas.
Russian Thistle exploits disturbed natural ecosystems, making it difficult for native plants to become reestablished. Fortunately, it is generally out-competed by natives in undisturbed habitats. Tumbleweeds can easily start and spread wildfires since they are dry vegetation which are easily tossed around by wind.