This tall, narrow, single-stemmed plant with trifoliate compound leaves is now sprouting up like crazy along roadsides and in grassy areas. It is a form of bush clover (Lespedeza spp.) and, based upon the pointy spike at the end of each leaflet, appears to be the highly invasive silky or Chinese bush clover (L. cuneata, for which see this Illinois description and this Missouri description). For how this plant looks in the fall after going to seed, see this post from last October, where I misidentified it as Scotch broom, a related trifoliate legume (this did not burst into yellow flower in spring as predicted; as a matter of fact, the plants have really emerged only in the last month or so).
This tall spindly plant with tiny white flowers can be found north of the W&OD bike path between Isaac Newton Square and the driveway for the Oak Hill Christian School. It is white sweet clover (Melilotus albus, see this Missouri description), yet another highly invasive trifoliate legume.
At the edge of the parking lot for 1801 Robert Fulton Drive, just south of the picnic area for the W&OD bike path, is this unassuming cluster of yellow eight-rayed flowers with very wiry leaves that are whorled around the stem. This appears to be thread-leaved tickseed (Coreopsis verticillata), for which see this Floridata record.
In the median between the W&OD bike path and the W&OD gravel path just south of Sunset Hills Road is this small meadow of gently swaying perennial ryegrass (Lolium perenne, see this Missouri description and thisOregon State treatise), just developing its inflorescence.
On the north side of the W&OD bike path just west of its intersection with Wiehle Avenue one can find this milkweed (Asclepias spp.). It has rather narrower leaves than the common milkweed (A. syriaca) found elsewhere, and its inflorescence is at the apex of the plant, rather than hanging from its shoulders. This appears to be swamp milkweed (A. incarnata, for which see Missouri description and this Illinois description).
The sumac (Rhus spp.) are now in bloom, as here on the north side of the W&OD bike path between Isaac Newton Square and the driveway for the Oak Hill Christian School. This particular specimen is not the winged or shining sumac (R. copallinum) found more commonly around here (the leaf lacks the characteristic wings; compare this post from last September), but instead is smooth sumac (R. glabra, for which see this Virginia Tech fact sheet).
Further west, on the south side of the W&OD bike path just east of Old Reston Avenue, this sumac is already breaking out into fruit. I wasn't able to quite get close enough to see what kind of sumac this is.
And finally, a nice illustration of how morning glories come by their name. This is the same specimen of wild potato vine (Ipomoea pandurata) featured in this post from last week. But whereas that picture was taken at 10 a.m., while the funnel-shaped flowers were at their peak opening, this picture was taken around 5 p.m. and shows the flowers rolled up against the day's heat.