Ground cover - April 23, 2010

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.

Afternoon of October 19, 2009

After 5 days of rain, finally a sunny fall day!

These are the field thistles (Cirsium discolor) that are between the W&OD bike path and W&OD gravel path just north of the Dulles Toll Road bridge.  For pictures of them in flower almost three weeks ago, see this post.

Now the thistles have gone to seed, with the seeds located at the bottom of tufts of long white hair that will carry them away with the wind.

Along the W&OD bike path between Sunset Hills Road and Michael Faraday Court one frequently encounters sassafras (Sassafras albidum) in the understory.  These trees are easily identified by their trident-shaped leaves.  Compare the Virginia Tech fact sheet.  The leaves are now beginning to turn to attractive yellows to reds.

Here is an earlier view of an understory sassafras tree along the W&OD bike path just north of Sunset Hills Road taken exactly four weeks ago.

On the north side of the W&OD bike path just west of Michael Faraday Court there is a stretch of about 20 feet where one will encounter frequent specimens of this grass.  From Lauren Brown's Grasses:  An Identification Guide, I believe this is rye (Secale cereale) and not one of the native wild ryes (Elymus spp.), because the head of fruit has rather long bristles and sometimes nods.

Secale cereale is the rye that is cultivated and from which rye bread is made.  But it also readily escapes from cultivation and can become weedy along roadsides and abandoned railroads - which is exactly what the W&OD trail is.  Given that, fifty years ago, this land belonged to the A. Smith Bowman distillery, which used rye (among other grains) to produce its Virginia Gentleman bourbon, it is entirely possibly that rye used to be cultivated in this particular patch and has persisted as a weed.

On the south side of Sunset Hills Road, between Isaac Newton Square and the pipeline, at the northwestern corner of the BAE Systems property, is this beautiful ornamental sweetgum (Liquidambar styraciflua), with its distinctive palmately lobed leaves.  Compare the Virginia Tech fact sheet.

This tree is now gloriously full with the characteristic gumball fruit.

Further west along the south side of Sunset Hills Road, the northern edge of the Plazamerica property is lined with ornamental sawtooth oaks (Quercus acutissima).  These oaks have long slender unlobed leaves like the willow oaks (Q. phellos) shown in this post, but are definitely a different species - note the bristly spines along the leaf edges and the exuberant fringe of scaly outgrowths covering the acorn cups.  Compare the Virginia Tech fact sheet.

Like the willow oak, the sawtooth oak belongs to the red oak group, which has acorns maturing in two years (unlike the white oak group, whose acorns mature in just one year).  The previous image showed some dark brown and mature acorns;  this picture, taken from the same tree, shows a green immature acorn that thus appears to be a year younger than the previously shown ones.

This tree, slightly further west than the previous one and more exposed to the sun, appears even further in its development - it has already dropped its mature acorns, leaving behind just the fringed cups.

Along the north side of the Plazamerica parking garage, fronting Sunset Hills Road, is this ornamental planting of oak-leaved hydrangea (Hydrangea quercifolia), which is acquiring a very attractive fall coloration.  Compare this data sheet from Missouri.

Let us now return to wildflowers!  Nestled among the mile-a-minute vines that infest the southeastern corner of the intersection of the W&OD bike path with Old Reston Avenue one can find this white five-petaled flower with a prominent cone of five anthers and distinctly lobed long leaves.

This appears to be Carolina horsenettle (Solanum carolinense), which, despite the name, is not actually a nettle, but rather a nightshade, closely related to eggplant and a bit more distantly to tomato and potato.  Compare this Illinois description and this Connecticut write-up.

Earlier this afternoon I had encountered another clump of Carolina horsenettles along the path leading from the parking lot of 1801 Robert Fulton Drive to the W&OD bike path.  These plants are obviously further along in their development;  they have finished flowering, and their berries (rather like small grape tomatoes, no?) are starting to ripen.  Warning - these berries are quite toxic.

And now for an old standard - yes, of course there are dandelions (Taraxacum spp., most likely T. officinale) in Reston.  This one is found in the lawn on the south side of the W&OD bike path just east of its intersection with Old Reston Avenue.

And where one sees a dandelion flower, one also soon sees a dandelion parachute ball ("Pusteblume", or "blow flower", in German), which contains the dandelion seeds ready for wind dispersal - just like the thistle seeds with which we started this afternoon.