This is the season when our gardens often look like the weeds are winning. In our mediterranean climate, winter rains bring weeds, many of them natives of The Mediterranean (the European or African lands that border the Mediterranean sea) so they are used to this winter rain-enabled life cycle.
While it is tempting to think of weeds en masse, there are a number of reasons to identify them. The skillful gardener notices new weeds and learns how to fight them before they get a root-hold, and knows which of the usual cast of weed characters have underground structures (like bulbs or running roots) that must be removed if one is to get rid of them.
Identifying weeds can be difficult, but if you can get as far as common name, you can learn quite a bit about your weeds on the following two web sites designed for California gardeners. And, knowledge, as they say, is power.
Find weeds by common or scientific names, read about them or see photos. Look at the national weed list & at the California weed list. Check out the pdf of the Noxious Times, the California Dept. of Food and Agriculture weed management newsletter.
This site offers a weed photo gallery that is searchable by common name. From here you can also go to the same weed list searchable by scientific name or by plant family name. You can also read about weeds that cause problems in turf.