Oakland marijuana activists have taken a step toward asking California voters to legalize pot.

The ballot measure they filed Tuesday with the California attorney general's office would allow adults 21 and over to possess up to an ounce of pot.

Homeowners could also grow marijuana for personal use on garden plots up to 25 square feet.

The statewide measure needs more than 430,000 signatures to make the November 2010 ballot. It's the second pro-legalization measure filed in recent weeks.