In low wet places, a mat of green leaves and yellow flowers grows. The flowers have five glossy, spreading petals and many stamens. Pale green splotches dot the leaves, which are three-parted and ragged at their ends.
This is creeping buttercup, or Ranunculus repens. It’s a mildly invasive plant that is becoming common along trails and roadsides where it can form large patches. Its stem can sprout roots where it touches the ground, enabling it to spread easily.
This flower is a relative of the taller, leggy California buttercup (a native).
Flowers Of Marin 