White flowers (and a couple of yellow ones) - April 25, 2010

Another tree that is blooming spectacularly right now is the black cherry (Prunus serotina - see the Virginia Tech fact sheet).  This is a native cherry that grows much taller and blooms rather later than the imported Japanese ornamental varieties.  This particular specimen is in the northwestern-most corner of the Charter Oak apartment complex.

Those little white dashes that could be seen in the overview picture?  Each one is a panicle full of white five-petaled flowers.

Across North Shore Drive, on the southeastern corner of Temporary Road Park, are these ornamental viburnums, which are almost certainly doublefile viburnum (Viburnum plicatum, see the Virginia Tech fact sheet).

Looking closer at the flower clusters, one can see the large flowers along the outside of each cluster;  these large ones are sterile - they lack pistils and stamens, and consist only of petals.

Just north of the intersection of Sycamore Valley Drive with North Shore Drive is this black locust (Robinia pseudoacacia) tree, which allows me a better shot at the drooping white flower clusters than I was able to get day-before-yesterday.

At the edge of the basketball court on North Shore Drive near the border between the Sycamores apartment complex and the Ivy Square condo complex, I found this tiny yellow flower with a very distinctive leaf pattern - three heart-shaped leaves joined at their apex.

Here is another sample, from a meadow in the Charter Oak townhouse complex (this one also properly shows that the flower has five petals).  This is a yellow woodsorrel (Oxalis spp.), either common yellow woodsorrel (Oxalis stricta, see this Missouri description) or southern yellow woodsorrel (Oxalis dillenii, see this Missouri description).  I am leaning toward believing it to be the latter, as the flowers do seem to be solitary rather than branched.

Just north of the entrance to the Charter Oak townhouse complex is this fringe tree (Chionanthus virginicus, see the Virginia Tech fact sheet).  This appears to be a favorite ornamental of local transit agencies;  one frequently sees them at Park-and-Ride and Metro station parking lots.

A somewhat closer look at the long stringy white petals which give the fringe tree its name.

Just north of the fringe tree is this ornamental viburnum, which, like the doublefile viburnum pictured earlier, has a ring of sterile flowers ringing the outside of each flower cluster, but which also has three-lobed rather than simple leaves.  This appears to be highbush-cranberry (Viburnum opulus var. americanum, see this Vanderbilt description and the Virginia Tech fact sheet).  And yes, that is a honeysuckle at the very left of the image.

Finally, I found this small yellow flower (a bit bleached in flashlight) underneath the hollies on the walkway connecting the Charter Oak townhouse complex with the Charter Oak apartments.  Note the prominent green sepals separating the five yellow petals, and the trifoliolate compound leaves with rounded serrations.  I believe this may be mock strawberry (Duchesnea indica, see this Missouri description), which is closely related to the cinquefoils (Potentilla spp.).

Understory - April 23, 2010

North of the W&OD gravel path, between the pipeline easement and American Dream Way, is this rather tall flowering herb with very serrated opposite triangular leaves, four-petaled white flowers, and spiny bracts.  This appears to be garlic mustard (Alliaria petiolata, see this Missouri description), which is considered a bad invasive plant (see this link).

Nearby is this specimen, which has denser, less serrated leaves and no bracts, but I believe it may still be the same species.

On the south side of the W&OD bike path, just east of its intersection with Michael Faraday Drive, is this viburnum bush (Viburnum spp.) that was already featured in full fruit in this post last fall.  Back then I suggested this might be wayfaringtree viburnum (V. lantana), although I'm now thinking it might also be leatherleaf viburnum (V. rhytidophyllum, see the Virginia Tech data sheet).  Unfortunately, I did not pay attention during the winter as to whether this was evergreen or not.

Trees - April 23, 2010

While male strobili are already fully developed on Virginia pines (see this post from earlier in the week), they are not yet apparent in Eastern white pine (Pinus strobus).  Instead, all we have yet are these new shoots that will eventually develop either male strobili or female cones.

Note, though, how abundant the shoots are, at the end of each branch and branchlet - once the strobili develop, their pollen will be overpowering!  This specimen is in the parking lot of 1801 Robert Fulton Drive.

Meanwhile, this blue spruce (Picea pungens) near the entrance to 1801 Robert Fulton Drive (part of the group featured in this post from last fall) is in full "bloom".

Note the solitary male strobili hanging from the ends of the branches.  Also barely visible are several mature cones from last year that have already opened up and dropped their seed.

Here one can also see a new cone, still light brown and with its scales relatively closed.

Meanwhile, there is one large flowering tree that is now spectacularly in bloom - the black locust (Robinia pseudoacacia, see the Virginia Tech data sheet).

This specimen, which still has few leaves and thus is almost all white flower right now, is located on the north side of the W&OD gravel path just west of its intersection with the driveway for the Oak Hill Christian School.

This specimen is located along the southern border of the Sycamores apartment complex.  It has already leafed out more, showing the characteristic pinnately compound leaves of the black locust.  But this also shows a somewhat closer look at the drooping clusters of flowers - rather similar to the wisteria flowers, which is not surprising, given that both are members of the Fabaceae or pea family.

Near the black locust just shown is this black walnut (Juglans nigra), which is also in bloom, albeit not very spectacularly - note the hanging catkins of green male flowers in the center of the image.

A closer view of the black walnut catkins.  For a picture of black walnut in fruit last fall, see this post.

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.

Late afternoon of April 20, 2010 (continued)

As a ground cover on the sun-receiving north side of the W&OD bike path one now frequently encounters this five-petaled white flower, which is associated with serrated three-lobed or trifoliate compound leaves.  I believe this is dewberry (Rubus flagellaris, see this Virginia Tech fact sheet and this Missouri description).

This plant forms long trailing or flat-lying vines which, as I verified by hand, have curved prickles along them.

Also bursting forth into flower all along the W&OD bike path now is the Amur honeysuckle (Lonicera maackii, see the Virginia Tech fact sheet), as seen here east of Michael Faraday Drive.  For a view of the prolific berries of this plant in the fall, see this earlier post.

This is a bush honeysuckle rather than a vine honeysuckle, so it is not Japanese honeysuckle (L. japonica), and the petals are not evenly spaced around the flower, so this is not Morrow's honeysuckle (L. morrowii).  Instead, four of the petals are fused into an upper lobe, which is characteristic of the Amur honeysuckle.

Another invasive species blooming profusely right now is the winged burningbush (Euonymus alatus), which has rather small, inconspicuous yellowish-green four-petaled flowers.  It is far more noticeable in the fall, when its leaves turn a bright burning red, as seen in this post from last fall.

On this particular specimen, which is a feral plant on the north side of the W&OD bike path east of Michael Faraday Drive, the wings of cork that give this species its name are also very noticeable, far more so than on the ornamental specimen in this post.  As this very informative Ohio State article points out, the wings that are very distinctive in the wild-type have been largely bred out of the "compacta" cultivar that is most commonly used for ornamental plantings.

Meanwhile, poison ivy is not yet in bloom, although the developing flower buds can be clearly seen in this image from east of Michael Faraday Drive.

Finally, in the southwestern corner of the intersection of the W&OD bike path with Michael Faraday Drive is this hydrangea  plant in full snowball bloom.  The leaves are lobed, and thus it appears to be some form of oak-leaved hydrangea (Hydrangea quercifolia), but the leaves are much smaller, and the flowers are blooming much earlier than those on the ornamental specimens near Plaza America featured in this post from last fall.  There are many cultivars of hydrangea bred by humans, and thus the specific identification is beyond my means right now.

Added by edit April 25, 2010:  Oh, how embarassing!  This is not a hydrangea at all, but rather a snowball bush cultivar of the European cranberrybush viburnum (Viburnum opulus var. opulus, see the Virginia Tech fact sheet and this Missouri gardening site).

Late afternoon of April 20, 2010

First for some of the showy stuff.  Right outside the front entrance of the Access National Bank building at 1800 Robert Fulton Drive these tulips (Tulipa spp.) have been now blooming for more than a week.  There are more than a hundred species and countless cultivars of tulips (see this Wikipedia article), so I'm not even going to attempt to botanize these.

It is now also the season for wisteria (Wisteria spp.) to bloom, as in this specimen at the southwest corner of Sunrise Valley Drive and Cross School Road.  Wisteria are highly invasive vines and are among the eight prohibited plants in Reston.

I am not really able to tell whether this is Chinese wisteria (W. sinensis - see this Virginia Tech fact sheet) or Japanese wisteria (W. floribunda - see this Virginia Tech fact sheet).  The most definitive distinguishing characteristic appears to be the direction in which the vines twine, but I was not able to observe any twining.

However, it would appear that all flowers on the raceme opened at the same time, which would suggest Chinese wisteria.

In open patches of uncultivated grassland, such as this spot between Robert Fulton Drive and the W&OD bike path just north of Sunset Hills Drive, there is also a profusion of this showy yellow plant.

This is common winter cress (Barbarea vulgaris), also known as "yellow rocket" - see this Connecticut description and this Missouri one.  This particular specimen was photographed in the early morning of April 20 along the W&OD bike path north of Sunrise Hills Road.  Note the four-lobed flower and the sessile leaves.

Along the W&OD path one now also frequently encounters this erect, fast-growing plant with opposite, squarish leaves that closely hug the stem.  This is common milkweed (Asclepias syriaca), so named for the milky sap of its main stem.  See this Missouri description, this Virginia Tech weed guide, and this Wikipedia entry.

Added by edit on June 6:  This is not milkweed, but rather Indian hemp (Apocynum cannabinum).  Both have opposite elliptical leaves that cling to a single stem when emerging, but the Indian hemp is more gracile, with leaves spread farther apart.

In certain favored spots, such as here on the slope between Robert Fulton Drive and the W&OD bike path north of the winter cress meadow previously shown, the milkweed forms rather extensive thickets.

Along the W&OD gravel path, as here between Sunrise Valley Drive and the Dulles Toll Road, the  Virginia pine (Pinus virginiana) is also spectacularly in "bloom", with the male strobili fully developed and ready to shed their pollen.

This image shows some of the new strobili adjacent to several old female cones that have long ago dropped their seeds.  Note the recurved spines on each scale of the cones, which are characteristic of this species, together with the short, paired needles.