Forty-one of us from the Maryland Native Plant Society, Virginia Native Plant Society, and Arlington Regional Master Naturalists - or member of all three as Cris Fleming pointed out! - met on a cold December 19th for a hike and traditional solstice hooley at the exceptional Travilah Serpentine Barrens in Montgomery County, MD, the mid-Atlantic region's finest example of a globally-rare, forested serpentinite community. Thanks to all who braved the cold and brought good cheer to the walk and toasting ceremony. This year's offerings were the heavily-peated, bog-and-sea coast inspired Ardbeg and Clynelish drams, as well as Knappogue Castle Single Malt Irish Whiskey and a fine French rum (compliments of Tom Raque). We were also glad to have the MNPS and VNPS state and Potowmack Chapter presidents with us.
2010 Travilah Barrens Winter Solstice Walk participants gathered in Post Oak (Quercus stellata) glade. Photo by R.H. Simmons.
Much of the vegetation that occurs on the olivine-rich serpentinite (dunite) at the Travilah Serpentine Barrens in Montgomery County is probably most appropriately classified as "Ultramafic Woodlands and Barrens", which is a natural community type within the "Low-Elevation Rock Outcrops and Barrens" group within the "Terrestrial System" category (see http://www.dcr.virginia.gov/natural_heritage/ncintro.shtml and http://www.dnr.state.md.us/wildlife/Plants_Wildlife/Md_Veg_Com/toc.asp). The relative abundance and co-dominance throughout the site of Post Oak (Quercus stellata), Northern Red Oak (Quercus rubra) - in sections, Blackjack Oak (Quercus marilandica), Shortleaf Pine (Pinus echinata), Virginia Pine (Pinus virginiana), and Little Blue Stem (Schizachyrium scoparium) - dominant grass under powerline - are strong indicators of this type. [Little Blue Stem when greatly abundant/dominant is a good indicator of ultramafic soils, like those derived from serpentinite, while the abundance of Indian Grass (Sorghastrum nutans) in places like Manassas Battlefield Park, Hoyles Mill, Gettysburg, etc., is a good indicator of underlying diabase (mafic rock) and Triassic Basin soils. Magnesium is very high in serpentine soils, but calcium levels are very low. Diabase soils are generally high in both calcium and magnesium.] Other distinctive plants when in association that frequently occur throughout the site in woodland glades with the above are: Wild Crabapple (Malus coronaria), Hawthorne (Crataegus spp.), Deerberry (Vaccinium stamineum), Bosc's Panicgrass (Dichanthelium boscii), and Leonard's Skullcap (Scutellaria leonardii), among numerous others.
Hiking up the powerline at the Travilah Serpentine Barrens through prairie-like community dominated by Little Bluestem (Schizachyrium scoparium). [The other grass that resembled Broomsedge (Andropogon virginicus) and occurred fairly frequently under the powerline was Elliott's Bluestem (Andropogon gyrans)]. The powerline maintenance folks - PEPCO? - need to zap the Phragmites colonies that're growing in a couple of isolated cells in seasonally-wet areas under the powerline, in addition to carefully controlling a few other weeds before they get going. Generally, the site is remarkably free of invasive exotics.
Powerline at Travilah Serpentine Barrens, Montgomery County, Maryland. Photo by R.H. Simmons.