As a Midwesterner (but also someone still relatively new to admiring plants), last year I only began to notice spring wildflowers by around April or May.
That's when you'd expect wildflowers to begin appearing in Illinois, after all. And while it's true that spring wildflower season in southern California does not reach its height until approximately the same time, there are signs of spring as soon as the first rains arrive. This season, that meant as early as November.
For me it was an odd sight. Grasses began to green. The humidity was higher than usual: on Thanksgiving Day, we actually turned on our air conditioning. By Christmastime, leaving our apartment complex at 5am for the flight to Chicago, my wife and I heard the chorus of treefrogs from a pond in the distance.
By January, in the hills I saw the youngest sprouts of wild cucumber (more interestingly known as manroot), and in a few cases, even some small fruits already developing. I witnessed tiny ferns growing in Baker Canyon on the Irvine Ranch, and giant ferns profusely scattered along the oak- and sycamore-shaded slopes of Trabuco Creek.
Today, in February, I saw Fuchsia-flowered gooseberry (Ribes speciosum, below) well in bloom. Did they begin blooming as early as January? You'll have to ask either a more observant flower-enthusiast than I, or a hummingbird. For the hummingbirds, this plant is the seasonal equivalent of an early breakfast.
While the flowers strongly resemble those of fuchsia, careful examination allows you to see it's actually in the currant family--as in the berry, like blackcurrant. (Examination need not actually be too close, as the many spines on its stem will attest just fine to its non-fuchsia status.)
California buckwheat (Eriogonum fasciculatum), whose tender but pointed, linear leaves stay green even throughout the dry season, has also begun to flower. During the dry season buckwheat flowers are still present as a dried, remnant cluster of dark red (seen in background, below).
They're quite pretty even then, but it takes spring to remind you of just how pretty buckwheat is when in bloom. Hopefully the bees are noticing as well, and making that delicious buckwheat honey of which I'm craving as I write this.
Buckwheat flowers themselves are nearly as striking as the pattern in which they grow off the stalk. I lack the botanical terminology to name this growth pattern, but the picture linked to here is worth those words.
And lastly, in the understory of a grove of live oak trees, I encountered a flower that was new to me: "Milkmaids", or California cardamine (Cardamine californica, below). The criss-cross, or "X" shape of the four petals, should have been my immediate tip off that this flower is a type of Mustard, that enormous (~3,700 species) order of flowering plants. More specifically, the Cardamines are the genus otherwise known as Bittercress, whose taproot and prolificness make them an annoyance of commercial nursery growers. These are among our very earliest of bloomers, arriving as early as December if enough rain has been present (Introduction to the Plant Life of Southern California).