I had a completely different post planned for today. Then this morning, between rain showers, I went on a walk along one of the creeks on the property, and found a colony of these dainty little wild violets growing in the shade.
Viola glabella, also known as Stream Violet, Pioneer Violet, or Smooth Yellow Violet, is a common perennial violet. This species is found in moist woodlands along the coast ranges in western North America and northeastern Asia, generally below 6500 ft.
Earlier this spring we found another native violet on the property, Viola ocellata, which seems more sun-tolerant than the Stream Violet. Viola glabella favors very moist woodland shade, and I only found it in one area near the creek, beneath a canopy of mature Redwoods, Fir and Bay Laurel.
Viola glabella grows 4-8 inches tall, and reportedly favors damp nitrogen rich soils in sites that periodically are subject to flooding. No doubt this lovely little plant is enjoying this week’s rain!
The flowers of Viola glabella emerge on slender stalks, and the petals are yellow on both sides, with the exception of the purple veined nectar guides on the lower three petals. Each flower has a spur behind the lower petal where the nectar is stored.
Note that the lateral pair of petals are bearded.
As an aside, Viola glabella was one of 50 stamps available from the United States 1992 Wildflowers collection.
The leaves of Viola glabella are bright green, heart-shaped with toothed edges, and deciduous. The plant dies completely to the ground in late summer, and doesn’t re-emerge until the winter rains arrive.
Plants spread via underground rhizomes, and from a profusion of tiny brown seeds produced in summer.
I haven’t been able to locate ethnobotanical data relating specifically to Viola glabella. However, the flowers are edible, and traditional uses of violets by Native Americans include using a poultice of leaves on skin sores and wounds (Costanoan, Iroquois), and apparently the juice of violets was used in dogs’ noses to clear out their nostrils, enabling them to track deer better (Thompson). 
Seeds and plants are periodically available through some native plant nurseries. As charming as this plant is however, if you have a small garden, be careful where you plant it, as apparently it naturalizes quite freely.
If you’re planning a hike into the woods over the next few weeks, pay close attention to the plants in the shade, and perhaps you’ll find some Stream Violets too.
 Daniel E. Moerman’s Native American Ethnobotanical Database