The fires that have ignited in California, leading to mass evacuations and seemingly otherworldly scenes, may have gotten their start from a surprising source.

Invasive grasses, or grasses that have encroached from other regions, can make wildfires more frequent, not just in California but nationwide, according to a study published Monday in the journal PNAS. The study looked at grasses like cane grass, which is native to Myanmar but is damaging ecosystems in Florida, and buffelgrass, which is helping to ignite fires in the Southwest and has origins outside North America.

“These grasses can act as kindling,” said Emily J. Fusco, a postdoctoral researcher at the University of Massachusetts, Amherst, and lead author of the study.

The species add to fire risk because they are growing in regions that once had far fewer grasses and because of their physical structure. Absent rainfall, the long, thin blades dry out quickly. This creates potential problems in places like California where most rainfall happens in the fall and winter, leaving the grasses to dry out in summer.