American Bladdernut (Staphylea trifolia)

American Bladdernut is widely distributed across the eastern United States from approximately western New England across much of the midwest into eastern Minnesota. In the extreme southern US, it is less frequently encountered but is scattered across MS, AL, and into the Piedmont of the Carolinas.   The presence of dangling "bladders" make the small tree easy to recognize throughout the winter.

The so-called bladders are actually papery textured, three-chambered capsules enclosing one or more hard, stony seeds. I opened a handful of capsules, expecting one seed in each of the 3 chambers. However, most had only one seed per capsule, a couple had 2, and only a single pod had 3 seeds. With a much larger sample, Harris (1912), writing in Botanical Gazette, found that longer pods tended to produce more ovules or seeds.

Seeds are bright & shiny, and bead-like. Those of the European species, S. pinnata, were regularly and widely used in rosaries (Lukzaj 2009, Dendrologicznego). Celts planted them on graves and other significant sites, and fossil remains are often associated with Roman & Medieval archaeological sites, often outside of its perceived native range (see Latalowa 1994 in Vegetation History & Archaeobotany).

In North Carolina our species, Staphylea trifolia, is typically a "bottomland" or "riparian" species; the bladders are thought to aid seed dispersal . I dropped a handful in water and the image (left) confirms, they do indeed float!  Perhaps not surprising, most naked seeds sunk rapidly. 

Water dispersal may explain why most of the stems I have observed along the Eno River in Piedmont of NC, are close to, or even overhanging the river.  

Typical habit of American Bladdernut
Along Eno River, Durham Co, NC
Note multiple, whitish-gray trunks above River Oats (Chasmanthium latifolium)

Image below (near the "Pump Station" on Eno River)
This part of the river floods more regularly than the above site, consequently
shows more extensive damage presumably from flood debris (see ground nearby)

American Bladdernut has oppositely arranged twigs and buds. Reddish-brown buds are evident in the winter (below; Jan 25, 2015). 

 

In the North Carolina Piedmont, Bladdernut buds began bursting open on March 22, 2015 (see above). Soon, the trifoliate leaves will be fully developed as shown on the specimen below:

Purple Mountain Pitcher Plants - New & Improved!

Purple Mountain Pitchers grow well in naturally occurring beds of Sphagnum moss
like these growing wild in Transylvania County, NC

Ron Deterrmann, has been tireless in his efforts
to secure conservation for Purple Mountain Pitchers  

                                                               Purple Mountain Pitcher Plants occur naturally only in a small region of the southern Appalachians (western NC, adjacent SC and GA).  There has been relatively little conservation attention focused on this narrow endemic, in part due to the relatively recent recognition of its distinctiveness. Schnell & Determann (Castanea 1997) published the new varietal status, thereby bringing needed attention to these unique plants.  


The NC Plant Conservation Program "protects" portions of two of the 8 known populations in the state (although perhaps more populations will become known as the NC Natural Heritage Program is just beginning to keep documentation on this plant for the first time (2014).

One of two protected populations mentioned above has approximately 150 clumps of pitchers and comprises what is thought to be the largest known population in the state. It is unclear why this population is so large compared to others in the region.  We do know that Sarracenia purpurea spreads slowly; Ellison & Parker (American Journal of Botany 2002) documented only a 5 cm median dispersal distance for pitchers in the northeastern US.  Further, Gotelli and Ellison (Ecology 2002) found that Purple Pitchers don't reproduce until individual rosettes reach 10 cm in diameter.  Our Southern Apps variety grows vigorously and flowers profusely in sunny & open habitats, as shown in the following image. In contrast, pitchers subjected to heavy

Mass flowering in an open, sunny, yet constantly moist habitat

shade lose vigor, diminish in size, and cease flowering.  The example shown below displays etiolated leaves typical of shading. This clump is actually smaller than the surrounding Galax foliage and has little chance of flowering or trapping insects. The site where it occurs has been heavily shaded for 20 + years.  It is unclear how long an individual pitcher clump or rosette can survive in dense shade.  Gotelli & Ellison (Ecology 2002) suggest rosettes may persist for 30-50 years, but this longevity is likely to be strongly affected by shading.  In any case, the diminished vigor translates to loss of reproduction, perhaps a significant reason other known populations are much smaller.  

Our large population was almost certainly larger at one time. We have documentation that the pitchers were "once so plentiful they sold for 50 cents a piece".  Even today, pitchers continue to be taken or poached hindering population expansion.  The first image below shows where an entire rosette was taken (depressed area directly in front of the remaining clump). The second image shows a clump partially removed (note the bud forming).  I guess in both cases the losses could have been far worse, eco-conscious poachers?

In spite of the poachers, we have extensively re-opened the site by removing dense shrubs.  Precise demographic data are lacking but we counted 32 flowers in 2012, 94 flowers in 2013, and 114 flowers in 2014. The majority of these flowers seem to be producing seed heads. It has been estimated that Northern Pitchers produce approximately 1000 seeds per head (Gotelli and Ellison, Ecology 2002). Although germination rates may be low, if seed production continues the population could begin to rebound. In fact, on a recent visit Ron Determann pointed out a few true seedlings..... with luck, continued management, patience, and support of our local poaching community the population may continue to rebound!

Purple Mountain Pitcher seed capsule 

Seedling Purple Pitchers

Prairie Flora in North Carolina - All Hands on Dock (Silphium terebinthinaceum)

Prairie Dock (Silphium terebinthinaceum), a.k.a Prairie Rosinweed, is among the most conspicuous herbaceous perennials of tallgrass prairies of the midwestern United States (1).  The same is true for certain remnant, prairie-like habitats in parts of the NC Piedmont as well. Part of its conspicuousness, no doubt, comes from the distinctive & large basal leaves that may reach 12" in length (see image below).

Flowering stalks bolt upwards in late July & early August, topped by ball-like buds. Stalks may reach 6-10 feet in height before opening into bright yellow flowers around mid-August.

Silphium terebinthinaceum basal leaves in Durham Co, NC

The epithet, "terebinthinaceum" translates to "with turpentine" a reference to the presence of rosins which give many species in the genus their common name. I assume the rosin content would be toxic or inhibitory to grazing animals, but rumor has it that the "rosin" was once chewed by pioneers and that the plant is actually favored by some grazing animals. Curtis (2) apparently observed a "virgin prairie" when it was first put to use as a livestock pasture. He indicated that the horses and cattle sought out prairie docks and compass plants "like hidden candy at a child's birthday party."  There are suggestions that bison also feed upon Prairie Dock, but I have found no definitive references to this, possibly because their ranges no longer overlap.

Prairie dock develops a significant taproot (see image at Reference # 3), unlike Silphium astericus with which it commonly co-occurs on many Piedmont, North Carolina sites. Dhillion & Friese (4) found that Silphium terebinthinaceum had high levels of mychorrhizal activity (a symbiotic association between the roots and specialized fungi that often confer advantages to the plant in the form of drought resistance, nutrient uptake, etc.).

Very little seems to be known about seed dispersal or pollination, but there are strong suggestions that both are extremely distance limited. Coupled with habitat fragmentation, the result is extreme isolation between remaining populations.

A review of the S. terebinthinaceum range map (see also #5) indicates that North Carolina populations are the easternmost in the nation, significantly disjunct from the heart of the main population centers in Illinois and Missouri (2). What is it doing here in the Piedmont of North Carolina?
 
                         

The NC Natural Heritage Program records Prairie Dock occurrences in Cabarrus, Davie, Durham, Granville, Mecklenburg, Stanly, Union, & Wake counties. Populations in Durham & Granville occur on rich clayey soils apparently weathered from diabase rocks, often with other species with prairie affinities. Until such sites are managed to maintain, or recreate, open conditions Prairie Dock appears to decline and persist only on road edges and powerlines.

Prairie Dock rosettes persisting along roadway in Durham (2006);
lack of mowing allowed dense saplings to encroach & suppress
 most individuals present

Same site as previous; mowed during growing season (May 2007)

Same site as previous; note numerous Prairie Dock rosettes (Sept 2007)

For long-term habitat improvement & maintenance prescribed fire is the most desirable technique and we have applied it with spectacular results at several Piedmont sites.  In most cases, our spring fires move relatively rapidly, exposing individual plants to direct heating for a short amount of time.  Hahn & Orock (6) found that Prairie Dock seeds are able to maintain viability even after 15 minutes of exposure to 150 degree C!

I concur with Schramm (6) "one would think that by now, fire would be universally accepted and vigorously applied in all restoration and management efforts, but fire is being used to conservatively." In addition, he says, "most remnants ... currently need regular burning to regain their original quality", a statement I also agree with in the Piedmont where prairie associated flora remains.

A grove of Prairie Dock flowering (Aug 2014) at site in Durham Co, NC
(same site as shown in preceding sequence)

REFERENCES:
(1) Gleason H.A. and Cronquist A. 1991. Manual of Vascular Plants of Northeastern United States and
Adjacent Canada. 2nd ed. The New York Botanical Garden, The Bronx, New York.
(2) Curtis, J.T. 1959. The Vegetation of Wisconsin. UW Press.
(3) Robertson, K. R. 2007 image.  see - http://www.inhs.uiuc.edu/~kenr/prairiephotos/silptere.root1.jpg
(4) Dhillion & Friese; http://images.library.wisc.edu/EcoNatRes/EFacs/NAPC/NAPC13/reference/econatres.napc13.sdhillion.pdf)
(5) http://plants.usda.gov/core/profile?symbol=SITE
(6) Hahn P.G. & Orock, J.L. 2014. Effects of Temperature on Seed Viabaility of Six Ozark Glade Herb Species and Eastern Red Cedar (Juniperus virginiana). American MIdland Naturalist 171: 147-152
(7) Schramm, no date; http://images.library.wisc.edu/EcoNatRes/EFacs/NAPC/NAPC12/reference/econatres.napc12.pschramm2.pdf

Two Rare Botanists on a Witch (grass) Hunt

  

Dichanthelium is "perhaps the most complex and confusing genus in our region" (1). 

Sometimes a mere one tenth of a millimeter difference in a critical measurement can separate two taxa!
For obvious reasons, most folks avoid these smallish and difficult to identify grasses (do you have a micrometer handy?).

But Johnny Townsend of VA Natural Heritage Program (below right) and Richard LeBlond  (right) (formerly of NC Natural Heritage Program) are hardcore enough not to be afraid of the Witchgrasses!

I had the unexpected pleasure to show them around to a few sites in Durham County recently. 

Johnny rarely travels to NC; the Commonwealth keeps him quite busy. 

Richard told me he had never really botanized in the Piedmont before.  

But they came & hopefully will both return!

On this day it was a quest for rarities; mostly taxa that Richard had either named or is working on, and that had been showing up in VA recently. We all hoped they would turn up on one or more sites nearby as well!

After a brief orientation, including review of some pressed specimens Johnny had brought along, Herb & Pat Amyx, Thomas Blaine, and the rest of us headed off in search of live material.  I found it difficult to train my eye to seperate the Dichantheliums from the other vegetation. More difficult was rapidly distinguishing the common species at a mere glance, like Richard and Johnny were able to do.

After traipsing by 7 or 8 other taxa in the genus, innumerable other native species, and just as the sun and humidity seemed to be peaking, Johnny dropped to one knee in front of Ringed Witchgrass (D. annulum). One of our targets was found! Was it the humidity or the excitement that made my legs buckle slightly?

Dichanthelium annulum displaying "autumnal" growth

Ringed Witchgrass was given its currently accepted name in a publication by Richard LeBlond in 2001 (2), elevating it from its former genus Panicum (along with a host of others).


Dichanthelium annulum is considered "significantly rare" in NC. Records have been documented from 15 locations around the state, but only 2 are considered extant in the Natural Heritage Program database (the other locations are historic, meaning they have not been observed for decades).




The bulk of the historic reports are from Piedmont counties including Person, Orange, Wake, and Durham (no apparent coastal plain records but Richard has just informed me of a collection from Roanoke Island!). The habitat has been listed in Weakley's flora as "dry sandy or rocky soil of open woods, dry grasslands, and barrens and glades..." Our site was in a frequently burned, open oak-hickory woodland, on rich clayey soils, with a diverse native ground cover.

Several stems of D. annulum rising above
Partridge Pea (Chamaecrista fasciculata), Earle's Blazing Star (Liatris squarrulosa),
Maryland Senna (Senna marilandica), and others

Most stems of Ringed Witchgrass were relatively tall (over 12") and showed the remains of spring culms and panicles. Roughly 1/3 of the way up the stem were tufts of new leaves slightly hiding newly developing branches or panicles. We found plants in several locations in the first site visited, usually in places where taller plants seemed to be less frequent. With this find, we can once again consider D. annulum "extant" in Durham County. 

After continued traipsing and hunting we visited another site. It wasn't long before Johnny made the second significant find of the day.....in a relatively bare patch of rich soil, exposed by recent spring prescribed fire.

Given the local conditions, this taxon was easier to see but harder to explain taxonomically. Currently treated as Northern Witchgrass (Dichanthelium boreale), but also indicated as Panicum bicknelli (1) Richard is working toward a nomenclature change that will treat this as Dichanthelium bicknelli. Regardless of the taxonomy, the plants found are also considered "significantly rare" in North Carolina.  If all the existing records are assigned to the same taxon, this will constitute the 13th or so record in the state, most of which seem to be considerably west of Durham, mostly in the mountains.

Very similar habitat (although not co-occurring) to Ringed Witchgrass, but overall, a much different appearance. These plants were much more clumpy than D. annulum with abundant, sturdier, basally disposed leaves.  An obvious rosette was present (below, left): perhaps these will be the overwintering leaves present in many species? Numerous flowering culms were present (below, right).

References:

(1) Weakley, A. S. 2012. Flora of the Southern and Mid-Atlantic States
(2) LeBlond, R.J. 2001. Sida 19: Taxonomy of the Dichotoma Group of Dichanthelium (Poaceae)


PARTING SHOT:

Richard LeBlond (right), "bowing down" before a rare specimen of (soon to be) Dichanthelium bicknelli. 

Prairie Flora in North Carolina: Eastern Gamagrass

Tall culms of Eastern Gamagrass in a "Piedmont Prairie" in central NC
with Daniel Overcash & Louis Suther

Eastern Gamagrass (Tripsacum dactyloides) is one of North Carolina's tallest and most robust native grasses.  A clump forming, warm season, perennial, with flowering culms that can reach 7-8' in height, the species responds well to fire and thrives in open sunny, yet somewhat moist sites.

Flowering Tripsacum dactyloides with pistillate (below)
and staminate flowers (above)

Tripsacum is monoceious, producing both male (staminate) and female (pistillate) flowers on an individual inflorescence.

Tripsacum is perhaps one of the most ecologically and agriculturally important native genera from North America. Widespread throughout the eastern US, Mexico, & parts of S. America, Tripsacum was a key ancestor of modern day corn (1) and could eventually contribute to agricultural sustainability efforts focused on perennial rather than annual crops.  At least one cultivar has been developed between Gamagrass and Zea mays that may be a step in that direction (2)

Tripsacum patch expanding in old field at Manassas Battlefield, VA

It produces significant live, leafy biomass with high live - dead ratio and is highly palatable for many grazers. Because of this excellent forage quality, Gamagrass is a classic "decreaser" in range management terminology; when present, grazers actively and preferentially seek it out and cause it to decline under sustained pressure.

Tripsacum dactyloides cupule with persistent pistillate flowers

In mid-summer, large seeds develop and ripen progressively from the top, eventually disarticulating when ripe (see image, right). Due to their size, they have little chance of dispersing far from the mother plant. Under intense grazing pressure or declines due to other factors, it is easy to understand why Gamagrass would be slow to recolonize. Heavy seed predation by rodents may also be a limiting factor in spread (3).

Individual seeds are enclosed in a hardened case sometimes called a "cupule". When intact, this structure can inhibit germination of the enclosed seeds (3)

Tripsacum dactyloides cupules on mineral soil 

Large clumps of Gama tend to develop a characteristic "hollow" in the middle of an almost circular ring of leaves.  As the clump develops upright stems, a tent of sorts forms over the nearly bare middle, providing nesting habitat for a number of ground nesting birds associated with prairies (4). Many such birds are among the most declining in the Piedmont region.

Tripsacum clump developing concentric ring,
 beneficial to some ground nesting wildlife

Herb Amyx, Joan Schnier, John Thomas, Jon Stucky
observing a riverside patch of Tripsacum

As suggested by its relatively wide natural range, Gamagrass is adaptable to a host of conditions. In part, this is due to extensive aerenchyma  root tissue (essentially air passages) that allow it to thrive in wet or even infrequently flooded situations (see image, left).

In addition, the roots are able to penetrate restrictive soils (including claypans) and survive droughts and other limitations that other species can not (5).






Consequently, Eastern Gamagrass can be an important member of a number of natural community types. These include certain blackland prairies in Texas (5), and coastal prairies in Louisiana and Texas (6). I have also observed Gama as locally abundant or dominant in longleaf pine woodlands in eastern Texas and other remnant, prairie-like communities in southeast Texas. In North Carolina, Tripsacum is an important member of what may be North Carolina's only remaining prairie, and is becoming locally abundant in several frequently burned areas elsewhere in the Piedmont providing clues to other habitats it may have occurred in.

Gamagrass clumps in an open woodland in which prescribed fire has been used twice
Durham Co, NC

Although Tripsacum dactyloides appears to be indicative of prairie-like habitats across North Carolina, and perhaps through its natural range, I hesitate to suggest "introducing" it to natural areas without first applying regular prescribed fire (and having the means to continue to do so), obtaining open habitat structure, removing invasive plants, and having a pretty good indication it may have been present historically.  Having said that, not every "restoration" of such habitats needs Gamagrass or likely ever had it. I prefer allowing even like sites to have their own unique floristic assemblages.

References:
(1) Eubanks, M. 2001.  The origin of maize: evidence of Tripsacum ancestory. Plant Breeders Reviews
(2) http://www.google.com/patents/US20140123357
(3) Anderson, R.C.  1985. Aspects of the germination ecology and biomass production of Eastern Gamagrass (Tripsacum dactyloides). Botanical Gazette 146.
(4) http://www.houstonaudubon.org/default.aspx?act=newsletter.aspx&category=Natives &newsletterid=1730)
(5) see http://link.springer.com/article/10.1023/A:1004256100631#page-1
(6) http://images.library.wisc.edu/EcoNatRes/EFacs/NAPC/NAPC04/reference/econatres.napc04.ocollins
(7) Diamond, D. D. & F. E. Smeins. 1984. Remnant Grassland Vegetation and Ecological Affinities of the Upper Coastal Prairie of Texas. Southwestern Naturalist 29.

Another Unexpected Discovery - Out of the Ashes

Michaux's Sumac (Rhus michauxii); Durham County (2014)

A series of unexpected and seemingly unrelated events (including encouragement from great volunteers, a last minute field trip venue change, perfect burn weather one fine spring day, a drenching downpour & flooded creek one late spring day, a new fire management partnership, etc...) conspired to produce spectacular results. 

In mid-May we held a field trip for members of the Friends of Plant Conservation (http://www.ncplantfriends.org). Guests and leaders alike were impressed with the results of a spring-time prescribed burn. Photo opportunities abounded (see image, left). There is nothing like seeing freshly sprouting plants invigorated after a burn!

While most people were snapping photos, some on their hands & knees, Lesley Starke called me over. She pointed to the small, hairy shrub (pictured above) and said, "is that what I think it is?"  But she already knew; we both instantly knew!  It's not every day one finds a new population of an endangered species, especially one of the rarest shrubs around.

Lesley Starke admiring her unexpected find

MICHAUX'S SUMAC IN DURHAM!!

What made this such an unexpected surprise? No previous survey work had associated Michaux's Sumac with these particular soils, and we did not believe the species native to the county.  Sure, there was a planted population elsewhere in the county but what did that mean? We had been frankly fixated on the other rare species present, namely Smooth Coneflower (Echinacea laevigata). Finally, the area had been literally "out of site and out of mind". Other than a single prescribed fire we conducted years ago, this area had received no management attention. The last time we burned nearby,  the area was avoided and had been languishing ever since. Fortuitously, early in the year I made a brief visit to the area with Herb & Pat Amyx.  We observed excellent restoration potential evidenced by numerous rosettes of Parthenium, and Helianthus atrorubens; we speculated on what might appear with appropriate restoration. Game on......and the hard work began.

We got an answer to our earlier speculation this May when over 40 stems of Michaux's Sumac were found!

Sumac Site shortly after prescribed fire & clearing

An abandoned railroad track runs through the middle of the site. In preparation for a controlled burn woody vegetation was cleared around the RR line (which also served as the fire line). The dense, dark woods toward the back right remained uncleared but were included in the initial fire; this tree density was typical across the entire length of the tract. 

Same view as above (approx.) several weeks later;
note flowering Sumac in foreground

Fire scars are evident on boles of shortleaf pines from the prescribed burn & orange-brown vegetation (back left) was top-killed by a more recent prescribed burn. The brush pile is one of many created from hand clearing.

During the prescribed fire, dense piles of pine needles and other leaves burned deeply exposing the RR ties underneath (we had stationed a pump unit there to wet the ties before they could ignite). All we really hoped for was flowering of the common species to benefit pollinators.

Michaux's Sumac (Rhus michauxii) flowering stem (foreground) with fire (background)

Michaux's Sumac (Rhus michauxii) was listed as federally endangered in 1989.  Although also endangered in North Carolina, the species is doing reasonably well in the sandhills region, where protected land and prescribed burning are relatively common. Populations in North Carolina's Piedmont have been all but wiped out. Loss of habitat to development and fire suppression are among the main culprits.

NOTE: Herb Amyx produced an excellent article on the Sumac which can be viewed here: (http://bwwellsassociation.wordpress.com/)

Restoring the Larkspur Savanna

Tall Larkspur (Delphinium exaltatum) approaches its southern range limit in North Carolina. Only a handful of sites have been documented and the species is considered endangered.  Of the 2 documented records in the Piedmont region, one is now extirpated (by the creation of a water line), and the second persists in a narrow slice of habitat between a paved road and a frequently disturbed water line.

Several years ago with the financial support of the NC Natural Heritage Trust Fund (now defunct), we were able to purchase a wooded tract adjoining the lone remaining Piedmont population.  The plan was to restore the densely forested tract hoping the Larkspur could re-occupy more natural habitat away from the constant threats associated with living on the roadside.

Dense patch of Eastern Red Cedar killed by
prescribed fire under large shortleaf pine

Since then, we have conducted 3 or 4 prescribed burns across the tract, combatted invasive species, and cleared some of the dense tree growth present.

The forest has scattered remnant trees with growth forms indicative of savanna growth. However, these were shrouded in dense growth of young Eastern Red Cedar (Juniperus virginiana) and little light reached the forest floor. Prescribed fires and selective tree removal have begun to produce desired results.

After several years, the upland edge of the site has begun to appear much more open.  In the following images a shortleaf pine and dogwood can be seen before and after preliminary restoration; more shortleaf pines become apparent deeper in the woods on the latter image.

   

Maintaining and expanding the developing "Larkspur Savanna" continues to demand resources. 

Restoration in progress at Larkspur Savanna, 2014 (above)
w/small pile of Eastern Red Cedar logs & brush piles
browned ground was dense Japanese Stilt Grass (Microstegium vimineum) 

Aerial views show the expanding opening.

Site in 2010, before hand-clearing

Site in 2013, after hand-clearing

Over the last several years we have been lucky to have several dedicated individuals carry the load of our restoration efforts at this site.

Earlier this year, Thomas Blaine has taken on thinning and brush-cutting to expand potential habitat. He shocked me, and perhaps himself, with discovery of the first Tall Larkspur plants outside of the original patch!

Not to be outdone, our local Preserve Stewards, Herb & Pat Amyx discovered a few more plants upslope of Thomas' just days later.  Taken together, these finds have expanded the extent of the Piedmont's lone Tall Larkspur population by more than 100 meters.