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.

Afternoon of September 27, 2009

The following pictures were taken near the eastern end of the hedgerow on the northern side of the Charter Oak apartment complex that separates the complex from the Hidden Creek Country Club golf course to the north.

Most of the trees in this hedgerow are tulip trees, also known as yellow poplars or tulip poplars (Liriodendron tulipifera).  They are instantly recognizable by their unique large four-lobed leaves.  Compare the Virginia Tech fact sheet.  The bud-like structure in the center of this picture is the fruit of this tree, consisting of numerous samaras that will apparently float off in the next month or so.

In the understory there is this isolated occurrence of tree of heaven (Ailanthus altissima).  Compare the Virginia Tech fact sheet.  This is a highly invasive weed species;  see this National Park Service fact sheet for details.

The large brown structures are the remnants of its seed pods;  from their size and number you can tell that this tree is a prolific seed producer, which is what makes it such a success as a weed.

Tree of heaven has large pinnately compound leaves, much like walnuts and sumacs.  The way you can tell a tree of heaven leaf is that each leaflet is smooth-edged except for a distinct notch near the base on both sides of the leaflet.  Walnuts and sumacs, by contrast, have serrate (finely toothed) leaflets.

Just beginning to bloom at ground level is this small-flowered white-rayed aster (Symphyotrichum spp.).  There are a large number of asters, which are apparently difficult to distinguish.  Cross-referencing the small-flowered white-rayed asters listed in Newcomb's Wildflower Guide to those listed as growing wild in Fairfax County in the Digital Atlas of Virginia Flora, it appears this could be either calico aster (Symphyotrichum lateriflorum - see this description from the Connecticut Botanical Society) or frost aster (Symphyotrichum pilosum - see this description from the Connecticut Botanical Society).

The hedgerow also features several black walnuts (Juglans nigra), which are now magnificently in fruit;  the green husks, which contain the walnut, are about 2-3 inches across.  Compare the Virginia Tech fact sheet.  Note that this is black walnut, and not butternut (J. cinerea), as the fruit are round rather than lemon-shaped.  Black walnut is found not infrequently in the wild woods of Reston.

 

Virginia creeper (Parthenocissus quinquefolia), with its distinctive five-part palmately compound leaf, is the dominant vine in this hedgerow.  Here it can be seen as both ground cover as well as climbing the trunk of a tulip tree.  This is the view from my living room window.

The dominant maple in both the hedgerow and the landscaped portions of the Charter Oak apartment complex is the red maple (Acer rubrum).  But the hedgerow also contains this sugar maple (Acer saccharum), with the leave shape familiar to us from the Canadian flag.  Compare the Virginia Tech fact sheet.

Toward the very eastern end of the hedgerow is yet another species of maple, the silver maple (Acer saccharinum), whose large leaf is deeply dissected.  Compare the Virginia Tech fact sheet.  The only other silver maple I have noticed so far in Reston is in the Charter Oak Townhomes complex.  In this image (which was taken pointing straight up), also note the pinnately compound leaves of a black walnut higher up in the canopy.