Vanishing Pine Barrens of the Washington DC Vicinity. Presentation by Rod Simmons. Sept. 17, 2016
Threatened Conifers of the World (web page)US Forest Service Silvics Vol. 1. Conifers (pdf)
Morse, Larry. 1983. Three Maryland stations for the Northern White Cedar Thuja occidentalis. Castanea 48: 159-161. (pdf)
Teague, J., L., et al. 2006. Upper Anacostia Watershed plant communities of conservation significance. NatureServe, Arlington, Virginia. (pdf) See p. 8 for a description of two kinds of "pine barrens" communities that were discovered in Prince George's County a decade ago and are believed to be closely related to vegetation previously known only from the New Jersey Pine Barrens. Both of the new community types are globally rare. One of them is tentatively named the Pine Barrens Pine - Oak community. The other is the Pine Barrens Lowland Forest, which is an unusual wetland type characterized by pitch pine and deciduous hardwoods in the canopy. Pitch pine is more characteristic of dry upland sites, but in the New Jersey Pine Barrens it also occurs in sandy areas that are saturated by groundwater. The occurrences in Prince George's represent a southern extension in the range of this rare vegetation type.
. Maryland Conservationist. A description of the bald cypress swamp as an argument for the protection by the Nature Conservancy.
USDA Plants Database Search Results for Conifers of Maryland (94 KB pdf)
Key to the conifers of Maryland (Word doc)
Gymnosperms vs. Angiosperms(external web page)