On the south side of the W&OD bike path, just east of its intersection with Wiehle Avenue, is a large patch of ground covered with this plant, which features heart-shaped leaves interspersed with small bluish-purple flowers. This is common blue violet (
Viola papilionacea, see this
Virginia Tech weed guide and this
Missouri description).
Another small flower now commonly found blooming along the W&OD bike path is the buttercup (
Ranunculus spp.). I have not been able to get a really good photograph of this flower, as the yellow is so intense that it always bleeds out. You simply have to take my word that the flower has five petals.
Another rather extensive buttercup patch, on the west side of the W&OD bike path just north of Sunset Hills Road. Based on the deeply lobed and dissected leaves, this could be either common or tall buttercup (
R. acris, see this
Connecticut description) or creeping buttercup (
R. repens, see this
Connecticut description and this
Seattle guide) among the buttercup species that are known to occur in Fairfax County.
In places, such as here at the southern edge of the Hidden Creek Country Club golf course where the W&OD gravel path crosses the pipeline easement, the buttercups are spread throughout the grass. If you click on the photo to enlarge it, you will also see that the buttercups are interspersed with tiny blue flowers (much smaller than the common blue violets) that have rounded, scalloped leaves.
This is ground ivy (
Glechoma hederacea). See this very informative
Virginia Tech weed guide, which includes hints on how to distinguish this plant from similar-looking weeds. The flowers are deeply tubed and thus definitely are not Veronicas. and the leaves are opposite along the entire stem.
Even more common than the buttercup as a source of yellow along the side of paths right now is, of course, the common dandelion (
Taraxacum officinale).
But I also found this much rarer small yellow flower, at the northern edge of the picnic area off the W&OD bike path just south of the Dulles Toll Road. This image was taken in the morning, and the flower was still pale and drooping, but the picture clearly shows that this plant has compound leafs of five serrated leaflets.
This image was taken about five hours later, by which time the flower had considerably perked up, revealing five yellow petals in a flower shape closely resembling that of other rose family plants, such as the cherries, pears, and apples. This is a cinquefoil (
Potentilla spp.); the name comes from the old French for five-leaved. Of the five species of cinquefoil known to occur in Fairfax County, this is either dwarf cinquefoil (
P. canadensis, see this
Missouri description and
Connecticut description) or common cinquefoil (
P. simplex, see this
Missouri description,
Illinois description, and
Connecticut description).
Finally, here is an image of a small ground-covering plant taken two weeks ago (April 12, 2010) that I've just now been able to identify. This is red deadnettle (
Lamium purpureum, see this
Wikipedia entry and this
Missouri description). This particular specimen was from the edge of the parking lot for 1801 Robert Fulton Drive near the picnic area off the W&OD bike path.
In essentially the same area one can find this somewhat taller white-blooming plant, with its characteristic small leaves closely held to the stem. I believe this is field pepperweed (
Lepidium campestre, see this
Missouri description and this
California photo gallery). There does appear to be a family resemblance i both the flower shape and the overall appearance of the plant to the common winter cress; this is not surprising, as both are members of the Brassicaceae or mustard family.
