Prairie Flora in North Carolina: The Partheniums

Dense Quinine patch in Durham County;
plants in the foreground are P. auriculatum, taller
stems in background are P. integrifolium

Wild Quinine (Parthenium integrifolium) and Glade Wild Quinine (Parthenium auriculatum) are frequent and sometimes common members of North Carolina Piedmont diabase woodlands. For unknown reasons, they may co-occur (as in the image to the left) or be found singly at a given site.

Both flower profusely in open, prairie-like sites, especially after burning although individuals may persist vegetatively for long periods under somewhat shaded conditions.

Wild Quinine is the wider ranging of the two, being found nearly throughout the eastern US (where often associated with high quality, prairie or savanna-like habitats). Glade Wild Quinine is the southern cousin ranging roughly from West Virginia to Alabama. The former may be found nearly across NC, while the latter is restricted to a handful of Piedmont counties.


     

Typical P. auriculatum
basal leaf

Typical P. integrifolium
basal leaf

              

                 

Both species have similar appearance with large, coarse, basal leaves.












P. integrifolium is much less hairy, often has a dark reddish mid-vein apparent on the larger, mostly basal leaves. It also tends to be a taller and larger plant when flowering (up to 3' or so).  P. auriculatum has a more petite, compact form, and longer blooming period. The toothier leaf margins help distinguish Glade Wild Quinine, and many plants show a sheen of white pubescence even from a distance while the hairs on Wild Quinine are much less developed and obvious.



The upper image (right) is Parthenum auriculatum, the lower is P. integrifolium; both in full flower (an insect has chewed into one on the lower plant.





           

Wild Quinine patch flowering after late spring
prescribed fire in Durham County
on exposed diabase outcrop

Large expanse of Parthenium integrifolium on a clayey, upland flat with deeper soils derived from diabase.
Site burned early Spring

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Diabase Rocks!

Diabase is an igneous rock type found in isolated bands in the Piedmont of North Carolina.  Some of the largest expanses are found in Durham and Granville counties. In these areas, boulders may be common and the soil surface is often interspersed with rocks.  The soils tend to be high in nutrients such as magnesium, have clayey textures, and shrink-swell properties.

(The boulder shown to the right occurs along the edge of a diabase sill in Durham County)

Many unusual and/or North Carolina rare plants may be found on diabase. A few of these are shown below.

Eastern Prairie Blue Wild Indigo (Baptisia australis var. aberrans): Globally rare & listed Endangered in North Carolina. Scientific nomenclature for this plant has varied through time and may continue to evolve. See Weakley's 2012 Flora for a discussion. Image from Durham County, NC

Tall Larkspur (Delphinium exaltatum): Ranked as globally vulnerable by NatureServe and listed Endangered in North Carolina. This image was taken at North Carolina's only remaining Piedmont population; the site in Durham County is now a Plant Conservation Preserve.

Crested Coralroot (Hexalectris spicata): Durham County, NC - wide-ranging & apparently globally secure, but significantly rare in North Carolina.

Hoary Puccoon (Lithospermum canescens); Limited to 2 NC counties and listed as Threatened in North Carolina

Low Wild-Petunia (Ruellia humilis): Widespread in US, but confined to a few Piedmont counties in North Carolina where it is listed Endangered. At least 2 populations are now protected on Plant Conservation Preserves. Image from Granville County

Smooth Coneflower (Echinacea laevigata): Federally and state endangered, extirpated from 2 states in its former range. Smooth Coneflower has been a focal species of conservation efforts in the Durham area since 2004.

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Shortleaf Pine (Pinus echinata) - Carolina Piedmont

Shortleaf Pine woodland with Post Oak (Quercus stellata) and Blackjack Oak (Quercus marilandica), Durham Co., NC

Increased attention is being focused on shortleaf pine by some foresters, ecologists, and restoration practitioners. An ongoing debate centers on how much shortleaf was present historically relative to the other native pines and hardwoods. We may never know the answer, however, it seems probable in our region (N.C. Piedmont) that mixed forest prevailed. According to Pinchot & Ashe 1897, "....no areas in the original forest...produce pure growth of either"

Range Map for Pinus echinata;
http://www.na.fs.fed.us/pubs/silvics_manual/Volume_1/pinus/echinata.htm

Although the preceeding map shows shortleaf ranging into the outer coastal plain there is general consensus that most of this area was historically dominated by other vegetation, especially longleaf pine woodlands and savannas. However, in the Piedmont there are intriguing "remnants" of shortleaf woodlands or savannas which share structural and compositional similarities with longleaf pine communities. 

Open Shortleaf Pine with herbaceous
understory including Indiangrass (Sorghastrum nutans)

Open Shortleaf "savanna"
 another view of well burned patch in Durham Co, NC

There is growing recognition that prescribed fire is an important management and ecological restoration tool in many shortleaf pine stands. To return long-suppressed stands to more open condition (such as the images above) frequent, regular fire is desirable. We try to burn these areas in the early spring on a 2-3 year rotation. 

  

Shortleaf Pine - Oak Forest; Spring 2014 prescribed fire

In the stand above, the nearly closed canopy from abundant oaks, especially Southern Red Oak (Quercus falcata), allows only patchy sunlight to reach the forest floor. Although fuel conditions were quite dry, the lack of sunlight penetration and wind movement underneath the trees and relative humidity in the high 30's fostered slow moving low flames and incomplete ground coverage.  

May 2014 Prescribed Fire in Shortleaf Pine - Oak Forest. Poverty Oat Grass (Danthonia spicata) is abundant and flowering in the left side of this view.  Patches of live green vegetation contributed to patchy coverage of this growing season burn.

Shortleaf Pine sapling on site burned ~ biennially for 10 years.
The small needles provide less surface for ice damage
than loblolly pine (Pinus taeda),
possibly explaining  its more northerly distribution.

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