Afternoon of October 22, 2009 (continued)

On the south side of the W&OD bike path, just east of its intersection with Michael Faraday Drive, and hidden among the mile-a-minute vines that are now dying back, is this full-in-fruit shrub, which appears to me to be a viburnum.  More specifically, this might be a wayfaring bush (Viburnum lantana), based on the red color of the fruit on their terminal clusters (we have not had our first autumn frost yet) and the rather narrow shape of the leaves.  Compare the Virginia Tech fact sheet and this page from Washington State University, which, however, shows rather broader leaves.

As one enters the oak-hickory forest of Lake Fairfax Park on the path that extends north from Michael Faraday Drive, one soon encounters mossy patches.  Here is an extreme close-up, which  shows that the moss patch is more than just velvety green;  there is actual structure, with branched stems.  I have to admit that I have no idea about the proper classification of this organism;  I am not even sure whether it is a true moss (division Bryophyta) or a spikemoss (genus Selaginella).  Lots of room for further education here!

O.k., back to vascular plants.  This specimen is on the south side of the Reston Association path from Tall Oaks shopping center just before it crosses North Shore Drive south of the Golf Course Island pool.  This is clearly a smartweed (Persicaria spp.) of some kind, but I am not sure about the species.  Note the dark splotch in the center of one of the leaves;  this would support identification as Lady's thumb (Persicaria maculosa), but the sheath around the leave nodes is not fringed.  Other possibilities are pinkweed (Persicaria pensylvanica) or pale smartweed (Persicaria lapathifolia).

A close-up of the inflorescence.  Compare to these Washington state pages on pale smartweed and Lady's thumb and this Illinois description of pinkweed (which, in this particular case, has white rather than pink flowers).  Whatever it turns out to be, it is not uncommon in Reston;  I have also encountered this plant in various shaded places along the W&OD bike path.

In the "underbrush" of the grass at this location one can also find this particular grass species, with its very distinctive radiating spikes lined with two rows of spikelets.

The parallel rows of close-fitting spikelets are particularly apparent when viewed from above.  Based on Lauren Brown's Grasses: An Identification Guide, this appears to be goose grass (Eleusine indica), which is a weed of disturbed urban areas.  Compare this excellent description from Illinois.

Towering over both the smartweed and the goose grass at this location is this graceful grass with its purple spikelets.

A close-up look shows that the ligule (where the sheath of the leaf meets the culm, or stem) is not very prominent, with perhaps just a hint of some hair.

Another overview shot to show how tall this grass is.  Based upon its height, late blooming, purple seedhead coloring, broad leaves, and lack of prominent ligule, I believe this may be purpletop grass (Tridens flavus);  compare this Illinois description and this Kansas description.

Added by edit August 7, 2010:  now that I have more experience looking at grasses, this identification is clearly wrong.  Yes, we have Tridens flavus in Reston, but it is generally smaller, and the leaves are not as prominently keeled.  Instead, this is a johnsongrass (Sorghum halepense, see this Missouri description and this photo gallery).  The prominently veined leaves are very similar to those of Eastern gamagrass, so these two species cannot be distinguished until the very different inflorescences mature.

Turning once again to trees, there is this spectacular ornamental tree in the open area at the center of the Golf Course Island cluster (south of Cypress Point Court, east of Torrey Pines Court, and west of the Golf Course Island pool).

In this picture (actually taken from a berm standing above the branch), one can clearly see that the needles are arranged in whorls - very different from the spruces and pines seen earlier this afternoon.  This whorled pattern indicates that this is a true cedar (Cedrus spp.), and the whitish-blue color of the needles suggests that this is an Atlantic cedar (Cedrus atlantica), cultivar "glauca".  Compare the Virginia Tech fact sheet.  This is closely related to the Cedar of Lebanon (C. libani), the biblical cedar from whose wood King Solomon built the first temple.

Some of the lower branches sport cones like this one.  These are the male cones, which apparently have recently released their pollen;  the female cones, just as in other species of the pine family, tend to be higher up in the tree and thus out of range for my camera.  Compare the third entry on this Hawaii guide to pine family trees.

Finally, another close-up to show that, while most hollies (Ilex spp.) are now sporting their red berries, this one, on the walk-way between Charter Oak Court and the Charter Oak town house development, is just now bursting into flower.

October 1, 2009

On looking at the vegetation lining the W&OD bike path (as here, just west of Wiehle Avenue), one can't help but notice large blotches of deep red spread among the green.

On closer inspection, these blotches turn out to be large clusters of blackish berries born on purple stalks.  Despite their similar color, these are not pokeweed (which are low-crouching shrubs rather than small trees, as these), but rather the fruit of Devil's walking stick (Aralia spinosa).  See the Virginia Tech fact sheet.

The reason for its name is evident from this image - don't try touching this trunk!

Another very prickly plant is the Mile-a-minute vine (Persicaria perfoliata), already described in this post.  Here it can be seen aggressively covering shrubs and even trees on the north side of the W&OD bike path west of Wiehle Avenue.

As compared to two weeks ago, most of this vine's fruit have now ripened to their characteristic blue color.

Not all the plants along the W&OD bike path are so forbidding.  There are, for example, also some nice clumps of goldenrods (Solidago spp.), as here on the south side of the path just east of Old Reston Avenue.  According to the Digital Atlas of Virginia Flora, there are 17 species of goldenrods growing in the wild in Fairfax County, and I have not even begun to study the distinctions among the specimens found here in Reston.

This might possibly be rough-stemmed goldenrod (S. rugosa) - see this Connecticut Botanical Society page - or early goldenrod (S. juncea) - see this page from same site.  Obviously I need to spend more time paying close attention to these plants.

Another plant displaying some color now is the honeysuckle (Lonicera spp.), which is now bearing juicy red fruit about the same size as the autumn olive.  This particular specimen is located near the clump of goldenrods shown in the previous two pictures.  The honeysuckle has opposite leaves, while the autumn olive has alternating leaves;  moreover, the honeysuckle's red fruit lacks the silvery speckles found on the fruit of the autumn olive.

This is either Amur honeysuckle (L. maackii) - see Virginia Tech data sheet - or Morrow's honeysuckle (L. morrowii) - see Virginia Tech data sheet.  Both of these bush honeysuckles are highly invasive imports from Asia and are now on Reston's list of "8 forbidden species" that may not be planted.

Further east along the W&OD bike path, on the south side just east of Wiehle Avenue, is another clump of plants now conspicuously in fruit.  The fruit consists of pairs of very long, very thin pods or follicles.

This is dogbane (Apocynum spp.);  see this comparable image.  There are two species growing in the wild in Fairfax County, spreading dogbane (A. androsaemfolium) and Indian hemp (A. cannabinum);  however, I don't believe I will be able to distinguish them until they flower next summer, as the first blooms pink and the second blooms white.

Late afternoon on September 21, 2009

Winged or shining sumac (Rhus copallina) in the weedy strip separating the parking lot for 1801 Robert Fulton Dr from the W&OD bike path.  Note the shiny wings along the petiole that joins the 11 leaflets in the compound leaf at the lower left.  For more on this species, see Virginia Tech tree factsheet.

The clusters of drupes on this sumac can get quite large.

Another shining sumac in the same strip, this one without the obvious clusters of drupes, but showing splotches of deep red fall coloration appearing.

In this particular weedy strip the pokeweed (Phytolacca americana) can get quite tall!

This strip also contains a large number of grasses, which add considerably to both the biodiversity and the beauty of this habitat.  This particular grass appears to be green foxtail (Setaria viridis), based upon its height, size and shape of panicle, drooping habit, and absence of hairs on the leaves;  see Virginia Tech weed guide.

Another view of a panicle from this grass, which is found quite frequently along this stretch of the W&OD bike path.

Mile-a-minute weed (Persicaria perfoliata) patch near the junction of the W&OD gravel path and bike path just south of the underpass under the Dulles Toll Road.  Note the distinctively shaped leaves (equilateral triangles), the round collars (ocreae) around the stem underneath some of the green fruit (especially in the lower center of the picture), and the bright blue color of the ripening fruit.  This is a highly invasive species;  see the National Park Service fact sheet.

Another view of this patch of mile-a-minute weed, with the prominent triangular leaves and a good example of an ocrea just underneath the blue fruit in the middle of the picture.  This particular patch has already climbed over some of the adjoining shrubs;  elsewhere along this stretch of the W&OD, mile-a-minute weed appears to be mostly a ground-hugging vine.

Cattail or bulrush (Typha latifolia) growing in a drainage ditch along the W&OD gravel patch underneath the Dulles Toll Road overpass.  I found this Wikipedia article on Typha to be informative.

A closer look at the distinctive cigar-shaped inflorescence of the cattail.