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:

Sessile Trillium - a rare myrmecochore in North Carolina

Trillium sessile: red petalled form in northeastern NC

Sessile Trillium occurs on the southern periphery of its natural range in northeastern North Carolina near the Roanoke River.  In Carolina this Trillium is known from two counties and is considered "Threatened" in the state.  Most individuals seem to have red petals as shown on the image above, but some individuals (as shown below) have greenish-yellow petals, apparently due to diminished or absent anthocyanins (for more information see Les etal. 1989; American Journal of Botany). 

Trillium sessile: light color form
Image date: 04/09/14

Sessile Trillium is widespread and common in the Missouri Ozarks and parts of the midwestern US. It is much less widespread east of the Appalachians although it does range across much of the Virginia Piedmont and into the coastal plain.  How does a species considered a "myrmecochore" (adapted for ant dispersal) develop a range like this?

For an excellent chance to see this rare plant in North Carolina, consider joining the Friends of Plant Conservation on April 07, 2015.  

More information can be found here:

http://www.ncplantfriends.org/Pages/FieldTrips.aspx

Spring Bartonia; Coastal Plain Endemic

Bartonia verna flowers (03/11/15)

Spring Bartonia (Bartonia verna) is an unexpected member of the Gentian family that appears in early spring. One of the many species first discovered by Andre Michaux, populations are restricted, or endemic, to the outer coastal plain of the southeastern US. The northernmost range consists of a single population located near VA Beach (Belden etal. 2004, reported in Castanea). Over half of the states where it has been documented consider it to be rare, including North Carolina.  A couple of the other states (MS, AL) have not explicitly considered its rarity, but like surrounding states it is almost certainly very restricted in those areas; Florida is the only state where the species is widespread (http://plants.usda.gov/core/profile?symbol=Bave2)

Spring Bartonia habitat at a site in South Carolina (03/11/15);
Pond Cypress depression pond with extensive standing water at flowering time

Sorrie & Weakley 1999 consider Bartonia's range generally synonymous with longleaf pine. The local habitat often includes wetland margins such as the example shown above on the Francis Marion National Forest.  The flowering Bartonia individuals located at this site occurred adjacent to pitcher plants, especially the Hooded Pitcher (Sarracenia minor), and Peanut-Grass (Amphicarpum muhlenbergianum). 

Bartonia verna multi-floral stem just opening

Bartonia verna in several inches of standing water; amidst brown stems of  Peanut-Grass

All Bartonia species (we have 3 in our area) are similar in having reduced leaves and root characteristics which may suggest a dependence on mychorrizal relationships to gain nutrients. Although B. verna has not been studied, Cameron & Bolin (2010) found that Bartonia virginica plants were enriched in carbon and nitrogen relative to surrounding vegetation and suggest that species is at least partially mycoheterotropic.

Cabbage Time in Carolina!

Skunk Cabbage (Symplocarpus foetidus) is one of our earliest, native bloomers. In mid-February, I observed dozens, possibly hundreds, of individuals pushing up through leaf litter, muck, and shallow water at a site near Warrenton, NC.

The stout emerging stalks are amazingly thick and leathery to the touch. They unfurl at various rates to form leafy "spathes".  I observed incredible variation in the appearance and coloration of these, ranging from light green to heavily striped, to mottled, to almost solid dark red.




Skunk Cabbage is a member of the Araceae family, which includes mostly tropical species. In our area its closest relatives include Golden Club & Jack-in-the-Pulpit.  Symplocarpus foetidus is the only species of the genus in North America; Western Skunk Cabbage belongs to a different genus. Symplocarpus also includes some disjunct members in eastern Asia. It has been suggested the Asian and North American species of Symplocarpus have been isolated from one another for over 6,000,000 years (1).

Symplocarpus foetidus spathe; few plants observed had
developed this perfect oval shape
Warren County, NC (Feb 2015)

Skunk Cabbage open spathe revealing enclosed spadix,
Note the amount of water inside the spathe

Skunk Cabbage is famous for the ability to produce heat during early season flowering, a process sometimes called "thermogenesis". Indeed, S. foetidus is one of the most precise thermoregulators known, and is apparently able to maintain temperatures within ~ 3.5 ° C range, while ambient temperatures range over 37.5 ° C (2). Exactly what value thermogenesis conveys to the plant, if any, is unclear. Some believe it is an evolutionary hold-over present in a few primitive plant families.

According to Seymour & Blaylock (3), "there is no doubt that warming advances development and permits early flowering, but the adaptive value of this is obscure".

I observed several plants with groups of what appeared to be fruit flies buzzing around. Some authors have suggested the plant's thermogenic qualities provide a more attractive site for early season insects like these. Grimaldi & Jaenike (4) found that Skunk Cabbage is "a major breeding site" for one species of fly that "looks enough like Drosophila so that the casual observer might be confused" (5); I certainly wouldn't have known the difference! Whether these insects pollinate the flowers on the spadix is unclear.

Symplocarpus foetidus "ripe" & flowering spadix

The condition and maturity of the spadix and presence or absence of flowers was quite variable during my visit.  The following series of images shows a bit of this, as does the image above (with the dark brown spadix). However, very few spathes were open enough to easily reveal the contents. Even fewer were flowering, like the examples shown to the left. Several appeared to be just past and others much more so, while at least one spadix (below) seemed to still bedeveloping.

S. foetidus immature spadix

This ripening spadix was
lying in an open spathe,
like an Easter Egg waiting to be gathered

Bright yellow stamens exposed, zooming into these seems to show pollen that has
fallen onto the spadix surface 

North Carolina has the southernmost ranging populations of Skunk Cabbage is eastern North America. The species creeps into a few northern mountain counties in eastern Tennessee and western NC. Further east, there are 3 or 4 reported counties in the NC piedmont.  The site for these images is in Warren County, close to the Fall Line.  Although often considered a piedmont county, it sure felt like I was in the coastal plain.  The habitat was a non-alluvial wetland ranging from moist to mucky soils. Tulip Poplar & Red Maple were probably the dominant trees, but Black Gum and an occasional Pond Pine were present, Cane & White Bay Magnolia were common as well. Most of the plants were found in and around the muckiest and wettest area near the streamhead.

Skunk Cabbage habitat (Warren County); Feb 2015
most plants occurred above the standing water where a faintly developed "Y"
can be seen, just downstream a dense understory of cane develops

Skunk Cabbage habitat, same site as previous (April 2014)

References:
(1) Jun Wen, R.K. Jansen, and K. Kilgore. 1996. Evolution of the Eastern Asian and Eastern North American disjunct genus Symplocarpus (Araceae): Insights from chloroplast DNA restriction site data. Biochemical Systematics & Ecology 24: 735-747.
(2) Seymour, R. S. 2004.  Dynamics and precision of thermoregulatory responses of eastern Skunk Cabbage. Plant, Cell,& Environment. 27: 1014-1022.
(3) R. S. Seymour & A.J. Blaylock. 1999. Switching off the heater: influence of ambient temperature on thermoregulation by eastern skunk cabbage (Symplocarpus foetidus). Journal of Experimental Botany 50: 1525-1532.
(4) D. Grimaldi & J. Jaenike. 1983. The Diptera Breeding on Skunk Cabbage, Symplocarpus foetidus (Araceae). Journal of the New York Entomological Society 91: 83-89.
(5) H. D. Stalker, 1945; On the Biology and Genetics of Scaptomyza graminum Fallen (Diptera: Drosophilidae).

Crater the bay to restore it?

Carolina Bay wetland (1998);
the egg shaped, dark mass near the center of the image

Carolina Bays are enigmatic, isolated wetlands scattered across parts of the Atlantic Coastal Plain; enigmatic due, in part, to their characteristic northwest-southeast orientation, and ovoid shape, not to mention speculation as to their origin.

Whatever their ontogeny, most have been destroyed by ditching, draining, and other land-uses.  Many appear only as faint impressions on aerial images.





One reasonably intact example of a Carolina Bay is the object of our conservation & restoration efforts in Sampson Co, NC (shown on the image above). This bay persisted amidst a maze of logging roads and uplands managed intensively for timber production, unlike an adjacent example which was repeatedly logged and shows few remnants of its original wetland character. I have no explanation why this particular bay was spared. However, remnant vegetation persists, displaying characteristics of "cypress savanna".

Cypress Savanna (Sampson Co, NC)
with open canopy, multi-aged, scattered Pond Cypress (Taxodium ascendens),
Loblolly pines are also evident, inc; browned & dying trees in the background

The dominant trees throughout the wetland would likely have been Pond Cypress (Taxodium ascendens). Like the image above, there would have been a relatively open canopy, with few Loblolly pines (Pinus taeda), above a dense, herbaceous dominated ground layer. However, most of the bay is now closed canopied and dominated by Loblolly which invaded the wetland due to a combination of periodic droughts and very infrequent fire. 

Pond Cypress (left), loblolly pine (right)

Pines grow alongside cypress (see left), sometimes capitalizing on what appear to be raised mounds created by the Cypress. Because Cypress is both slower growing and more shade intolerant than loblolly, the predictable result is that pines will eventually replace the cypress.  They also absorb and transpire more water, drawing down the water table and further increasing their competitive advantage. 




Therefore, a primary restoration issue is removal of the pines. 

Given the sensitivity of the site, conventional logging was not an option, and felling individual trees was deemed too labor intensive. After extensive consideration and experimentation, we decided to bring fire back to the bay and implemented a prescribed burn in the middle of November.  

Loblolly pine overtopping pond cypress

Fire weather forecasting called for northeast winds @ 9 mph, 55 degrees, 44% humidity. Keetch-Byram drought index (KBDI) was high (over 500), and fuel moisture across all size classes was less than 20%. The fire carried well across the entire site, as expected.  Flame lengths stayed generally low although there was significant variation as measured by scorch heights afterwards. Active fire burned out quickly and was easily contained.  Dry fuel conditions allowed fire to smolder pockets of surface organic buildup consisting mainly of intertwined pine roots.  

Post Fire Conditions in Carolina Bay after November fire

Top: small pocket burned several inches deeper than surrounding, 

Middle: Red Maple roots exposed, heavily injured & toppled

Bottom: consistent surface organic reduction, some root exposure 

As a result, a number of trees throughout the bay succumbed. A few, like the Red Maple (Acer rubrum) shown above fell over and died immediately, while most trees either survived or died more slowly. The following chart displays the survival of the three most common trees, Loblolly Pine ("Pinus"), Cypress ("Taxodium"), and Maple ("Acer") across 5 diameter size ranges.  For a given species the colored lines within each size class show the number of stems before fire ("Pre") and the number surviving after ("Post"). 

These data show relatively heavy stem losses of Pines (blue lines) across all size classes, while mortality of Cypress (red lines) was concentrated in the two smaller size classes. Taken together, this shows an overall shift away from the strongly pine-dominated vegetation of the Carolina Bay before fire to an equal mixture of pine & cypress after fire.  The lone fire was not sufficient to restore cypress savanna but it produced significant progress.

Growing season conditions following November fire;
Pond Cypress tree stands amidst several dead loblolly pines,
and above a living red maple

Maryland Senna - A Savanna Species in North Carolina

Maryland Senna (Senna marilandica) is a plant I don't often think about in the dead of winter, and especially in moist, riparian forests, but I recently walked by a patch laden with pods near the Eno River.

Senna marilandica full of fruit approximately 100' from the Eno River
(January, 2015)

Plants are stout, herbaceous perennials, to 6' or so tall in our area. In late summer they produce some of the brightest blossoms around, both at the top and axils of the main stem.

Maryland Senna, full bloom
(Durham County, 8/19/2014)

An interesting evolutionary aspect of Maryland Senna is the presence of extrafloral nectaries (EFN) near the base of the compound-leaved petioles.  In general, these nectaries are sugar producing glands that offer nectar to ants, who in turn provide protection to the plant from herbivores.

Extrafloral nectaries (EFN)  are the dark tick-shaped objects shown above;
the one to the upper left is being visited by a black ant
(Granville County, NC 8/01/12)

Maryland Senna EFN with ant visitor (Durham County, 08/20/14)  

Brigitte Marazzi and co-authors, writing in the American Journal of Botany (2006), documented that Senna species with EFN have colonized a wider range of habitats and climates than species lacking EFN. They believe the "ant–plant protective mutualism" has a positive effect on plant fitness and may help to explain the greater species richness of the EFN bearing Senna, as well as the greater diversity of habitats they occupy.

Maryland Senna EFN with a different visitor (upper left)
Note the developing seed pod (right)
(Durham County, 08/20/14)  

Other than the odd occurrence of Maryland Senna near the Eno River (powerline cut along with Heliopsis helianthoides), I find it most often in open canopied, uplands associated with diabase soils. I sometimes refer to these as savannas (never having seen the plant in closed canopied forests on the same soils and geology). One of the sites for some of these images has been referred to as a "cedar glade."  In their study of Piedmont Prairie remnants, Davis and colleagues (Castanea 2002) indicate Senna marilandica has a "strong association with Piedmont Prairies" although they did not document it at any of the sampled prairie sites, only a power-line right of way. There are numerous references in other parts of eastern North America to this species being found in prairie-like habitats. I was lucky to see it, or closely related species, in a Bur Oak Savanna in northeastern Indiana, late this November (see image below), which is managed by prescribed burning. 

Maryland Senna in an open, diabase glade, Granville Co, NC
The uppermost stem is full of buds, near a developing compound leaf  

Holy Moley!

Southern Star-nosed mole ((Condylura cristata parva)
Image location near Avery/Watauga Co line; Jan 02, 2015

While traipsing around in a high-elevation mountain bog over the recent holidays (certainly a great way to kick off the New Year) I encountered a true surprise!  Although I had never seen one before, I immediately recognized the critter shown above due to its distinctive fleshy appendage, sometimes referred to as a nasal star.  The unusual snout has been described as "a nose that looks like a hand and acts like an eye" and has been considered possibly the most sensitive touch organ among mammals (1). It turns out, the Star-Nosed Mole is characteristic of wetland habitats, such as the "mountain bog" where I encountered it, and unlike its relatives it remains active in the winter (both factors help to explain why I found the individual shown above). It also turns out that the star-nosed mole is a species of special concern in North Carolina (2), where they are often considered rare to uncommon, but sometimes locally abundant (3).  Star-nosed moles (Condylura cristata) range into Canada and the northeastern US. However, those restricted to the southern Appalachians have been considered a subspecies, Condylura cristata parva, the name I am applying here.

Habitat for the Southern Star-nosed mole in the northern mountains of North Carolina
Note: small stream channel on shallow, quartz gravel bordered by stunted & yellowing rhododendrons

Mountain bog habitats are an important conservation priority in NC and across the southern Appalachians. In North Carolina, a sizable number of imperiled plants occur in the small and isolated pockets of these wetlands that remain (although not all "mountain bogs" support rare or imperiled plants). Even though winter is not the best time for a plant survey, I did find a small clump of what I believe is Bog Clubmoss (Lycopodiella inundata). Here in NC this plant is considered significantly rare, being known from only a small handful (~ 3) wetlands in the mountains.

Compared to other NC mountain bogs I am much more familiar with, this site is higher elevation (> 4,600') and found in a less fragmented landscape. In addition, Sphagnum moss is more abundant than many other sites I have looked at. Hints of the high elevation come from the presence of Red Spruce (Picea rubens) and a couple of Ruffed Grouse I scared up. Cant't wait to visit this site again!

Red Spruce growing amidst Sphagnum Moss clumps in the wetland

References:
(1) Catania, K. C. 1999. A nose that looks like a hand and acts like an eye: The unusual mechanosensory system of the star-nosed mole. Journal of Comparative Physiology
185:367–372
(2) http://www.ncwildlife.org/portals/0/Conserving/documents/protected_species.pdf
(3) Webster, W. D. 1987. in M. K. Clark, editor. Endangered, threatened, and rare fauna of North Carolina. Part 1. A reevaluation of the mammals. Occasional Papers of the North Carolina Biological Survey 3.