I've always had a sneaking admiration for the adaptability of weedy species; they're amazingly flexible in their reproductive strategies -- annual (winter or summer), biennial, perennial -- either terrific seed producers or excellent vegetative spreaders. Lots of strategies!
Weedy winter annuals love our mild winters, so I always get lots of exercise pulling them up in open mulched areas. Fortunately, they're easy to pull, creating mounds of compostable material (composted 'hot' if plants have gone to seed.) Weedy species vary in their success year to year, but since winter annuals are adapted to quick growth at low temperatures, relatively speaking, and producing flowers and fruits quickly in spring, it's hard to keep ahead of their seed production.
And usually, I'm behind; even here in the Carolinas, it's often too inhospitable to get out and weed (uh, sometimes the weekends are cold and rainy, even if we do have perfectly nice days periodically in the winter).
So, I'm out there pulling up all the 'suspects' right now, chief among them ivy-leaved speedwell, Veronica hederifolia, which of course has already gone to seed. It wins the prize this year for peskiest winter annual. Whether it was the summer drought, followed by a decently damp winter, who knows?
I'll put on my plant ecologist cap for a moment and mention that for a winter annual, ivy-leaved speedwell has exceptionally large seeds. And, produces a LOT of them. It's pretty unusual for a weedy annual to produce seeds that large.
This is a species native to Europe that's well adapted to disturbed soil and open areas, so is at home in our mild winter areas.