P. van Rijckevorsel wrote:
Have you ruled out this ?
http://tncweeds.ucdavis.edu/photos/phrau13.jpg

"Andy Schecter" schreef
That looks close, although I am in a much colder climate than California.
Please see my reply to Peter B for more photos.

Well, if you have not ruled out the most obvious candidate (common reed),
then that is likely to be it.
PvR