ILLUSTRATED FLORA OF EAST TEXAS - Brit - Botanical Research ...

CURRENT VEGETATION OF PINEYWOODS/INTRODUCTION 97
sundew) and Sarracenia alata (pitcher plant). Eriocaulon decangulare (ten-angle pipewort),
Sabatia gentianoides (pinewoods rosegentian), Helianthus angustifolius (swamp sunflower), and
Sphagnum spp. (peat mosses) may also be found. Rare and sensitive species sometimes present
include Calopogon tuberosus (grass pink), Pogonia ophioglossoides (snake-mouth orchid),
Platanthera integra (yellow fringeless orchid), and Rudbeckia scabrifolia (bog coneflower).
Herbaceous seeps are rare as a result of the loss of longleaf pine woodlands, fire suppression,
and the lack of suitable soils and hydrology in many areas. Good remaining examples exist
in the southern part of the Angelina National Forest.
WET PINE SAVANNAHS—Also called “wetland pine savannas” (Marks & Harcombe 1981;
Harcombe et al. 1993), “pine flatwoods,” “longleaf-blackgum savannahs” (Ajilvsgi 1979), and
“pine savannah wetlands” (Watson 1975), these are longleaf pine communities characteristic
of poorly drained fine-sandy loams on nearly flat topography. They are found along the
southern edge of the Pineywoods closest to the Gulf of Mexico. According to Bridges and
Orzell (1989b), “Two major natural forces interact to produce this community—a fluctuating,
seasonally high water table and frequent, low-intensity ground fires. The fluctuating water table
naturally inhibits the range of tree and shrub species that can occupy the site, while the
periodic fires eliminate species tolerant of wetland conditions.” Sedges (especially Rhynchospora
and Scleria spp.) dominate, along with Schizachyrium scoparium (little bluestem). Drosera brevifolia
(annual sundew) may be abundant, but Sarracenia alata (pitcher plant) and Sphagnum mosses
are less common than in Herbaceous Seeps (Harcombe et al. 1993). Like all longleaf pine
communities, Wet Pine Savannahs have become increasingly rare in the absence of regular
fires. They have become overgrown with woody plants and converted to closed canopy forests
of Nyssa sylvatica (black-gum), Liquidambar styraciflua (sweetgum), Acer rubrum (red maple),
Magnolia virginiana (sweetbay magnolia), and lowland oaks. Examples occur in the Big
Thicket National Preserve (Ajilvsgi 1979; Marks & Harcombe 1981). According to
MacRoberts and MacRoberts (2001), the Preserve probably has the best remaining areas of
this community in the entire West Gulf Coastal Plain. Today less than one percent of the
pre-European pine savannahs in southeast Texas and southwest Louisiana remain as the
result of various anthropogenic activities including timbering, farming, urban sprawl, and fire
suppression (MacRoberts & MacRoberts 2000).
CLAYEY DRY-MESIC UPLANDS—Soils supporting this vegetation type are clayey almost to the
surface, with only a very thin loam topsoil. Often the clays have shrink-swell properties.
The soils may be saturated during wet periods because of slow percolation, but once dry,
water infiltrates slowly and drought conditions occur. On most landscapes these sites are
rare, the clayey soil conditions occurring as isolated inclusions on an otherwise loamy or
sandy landscape. Trees are often crooked or stunted and may have root damage from
shrinking and swelling of clays. Natural sites develop a mixed overstory of Pinus echinata
(shortleaf pine), P. taeda (loblolly pine), Quercus stellata (post oak), and Q. marilandica
(blackjack oak). Fine-textured soils historically favored hardwoods over pines, and many
such sites were probably oak-dominated even in presettlement times. Common shrubs are
Callicarpa americana (American beauty-berry), Ilex vomitoria (yaupon), Crataegus marshallii
(parsley hawthorn), and Forestiera ligustrina (upland swamp privet). A variety of ground
layer species, most of which are also common on other mesic and dry-mesic sites, occurs.
Trachelospermum difforme (climbing dogbane), Chasmanthium sessiliflorum (narrow-leaf
wood-oats), and Scleria oligantha (little-head nutrush) tend to be abundant. The Redlands
area near Nacogdoches is an example of such an area (Roberts 1881; Chambers 1941).
CLAYEY WET UPLAND DEPRESSIONS—These sites usually occur as isolated inclusions in most
landscapes. They form in slight depressions or flats on broad uplands with poorly-formed
drainage patterns and clayey or slowly permeable soils. A seasonally high water table
develops near the surface in most years, resulting in vegetation that more resembles that