This orange, stringy stuff shows up all over Pasadena's wild places this time of year. It's a plant with a stretchy, rubbery texture. If you enlarge this photo you can see what it's doing: strangling its host plant.
The orange parasite is called Cuscuta, or "Dodder." My friend, the landscaper Leo Snider (who's very knowledgeable about southern California native plants), says Orange Dodder's favorite host is sumach. Sumac recovers from the parasite over the winter, according to Leo, and from what I can tell so do the other plants it invades. "One nice thing," says Leo, "is that Dodder usually localizes. That is to say, it hasn't taken over the world."
Just a few defenseless locals.