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.

New(ish) to Carolina & Not Wanted: Spurred Anoda

Spurred Anoda in Catawba County, NC
Image Date: 9/12//2013

Spurred Anoda (Anoda cristata) is poorly documented in the Carolinas and was listed as "rare" and known only from Mecklenburg Co, NC in the Manual of the Vascular Flora of the Carolinas (Radford, Ahles, Bell, 1964).

The native range of Spurred Anoda is unclear but likely includes the southwestern US, and South America (where it is also considered an agricultural pest). In Mexico, there are numerous references documenting the uses of this species for food and medicine; the plant apparently contains significant amounts of ascorbic acid, retinol, iron, proteins and carbohydrates (see Bautista-Cruz et al., 2011; Journal of Medicinal Plants Research).



In Virginia, the species has been documented relatively widely in the coastal plain but only rarely in the Piedmont (http://www.vaplantatlas.org). An online search of the South Carolina atlas turned up only a single collection. In NC, the second documented report of the species comes from the northern Mountains,  "one of the three adventive species derived from bird seed waste" found growing under a bird feeder near Boone (see Poindexter et al., 2011; Phytoneuron).  I located what appears to be the 3rd known station for the species in NC in the Piedmont region (Catawba County) growing at the margin of a corn field along with a number of other agricultural weeds such as Cocklebur (Xanthium strumarium), Johnson grass (Sorghum halepense), Red Morning Glory (Ipomoea coccinea), and Pigweed (Amaranthus sp.).

Habitat location for Spurred Anoda in Catawba County along Carolina Thread Trail;
plants were growing at the very edge of the corn crop

Surprisingly, given the botanical status mentioned above, Spurred Anoda was listed as one of "Ten Most Troublesome Weeds In Cotton" in both NC and SC (see 2005 Proceedings, Southern Weed Science Society, 58).  In the Carolinas, it is unclear if the species is simply overlooked and under-collected by botanists or remains truly rare in NC & SC. The fact that Spurred Anoda appears to spread from commercial seed mixes is troubling and perhaps doesn't bode well for its future status in the state.



In the field, plants have light bluish/lavendar, 5 petaled flowers with radial symmetry, forming in the axils of leaves. Leaves are widest at the base, sometimes developing three lobes. Fruits, sometimes referred to as hemispheric schizocarps, are flattened, circular, segmented structures. Dense hairs are found on the stems, fruits, and less so on the leaves.  This is an annual which apparently spreads well from seed.

Large-flowered Milkweed (Asclepias connivens)

Large-flowered Milkweed is one of the more distinctive milkweeds of the southeastern states, due to the unusually large, deeply cupped, individual flowers, that may reach nearly an inch across.

Individual flower (corona) of Asclepias connivens, displaying the "connivent" hood

Phylogentically, A. connivens is intermixed with African Milkweed species in clades developed by Fishbein (1996), providing some suggestion that our North American species may be derived from Africa; perhaps this implies this is also one of our more ancient species?

Large-flowered milkweed is a relatively narrow southeastern coastal plain endemic, ranging from extreme southeastern SC through coastal GA, into extreme southern AL, and across most of Florida, In the northern Florida panhandle, Asclepias connivens can be found in poorly drained, silty soil habitats that have been called wet flatwoods or prairies (Carr 2007); these sites have sparse tree canopies and well developed herbaceous layers.  The images included here are from two regularly burned sites taken on the same date. Plants at the most recently burned site were somewhat delayed in flowering compared to the site burned earlier in the season.

A. connivens coming into bloom in
standing water, recently burned savanna
(July 04, 2014)

A. connivens flowering in dense sward of grasses and herbs
under sparse canopy of longleaf pine
(July 04, 2014)

One of the sites could also be called a "wet savanna".  It had a sparse tree canopy of longleaf pine and a few Pond Cypress (Taxodium ascendans), including the two tallest stems shown in the midground below.  Some naturally occurring slash pine (Pinus elliotii) were present (seeding in from the adjacent forested wetland), but most of the smaller stems were killed by the last prescribed fire. In addition to numerous stems of Large-flowered Milkweed other notable species included Toothache Grass (Ctenium aromaticum), Parrot Pitcher Plant (Sarracenia psittacina), Pale Grass Pink (Calopogon pallidus), and Tracy's Sundew (Drosera tracyi)

Awesome wet savanna on St. Marks National Wildlife Refuge
Thanks to Jeff Glitzenstein for getting me there!

References:

Carr, S.C. 2007. Floristic and Environmental Variation of Pyrogenic Pinelands in the Southeastern Coastal Plain: Description, Classification, and Restoration. PhD Dissertation.

Fishbein, M.  1996. Phylogenetic Relationships of North American Asclepias and the Role of Pollinators in the Evolution of the Milkweed Inflorescence.  PhD Dissertation.

A few Southeastern Coastal Plain endemics

Shiny Woodoats (Chasmanthium nitidum)
Wet hardwood hammock,
limestone close to surface
St. Marks NWR, July 2014 

Probably the rarest Woodoats grass or Chasmanthium species in North America, the natural range of Shiny Woodoats (Chasmanthium nitidum) is almost entirely found in Florida. The grass barely finds its way into NC where it is considered threatened, being known only from Pender County. 

Chasmanthium latifolium;
the most widespread member of the genus

Scareweed (Baptisia simplicifolia)
Pine Flatwoods, regularly burned
St. Marks NWR, July 2014

One of the Wild Indigos,  or sometimes called "Scareweed", Baptisia simplicifolia is a narrow endemic confined to a couple counties in north Florida's panhandle.

Limited to open pinelands, this is one of the many fire-adapted species found in longleaf pine flatwoods. At the end of the growing season, stems break off above ground and the plant blows around like tumbleweed, helping to distribute seeds still found in the capsules. The vast majority of the world's population is found on the Apalachicola National Forest.

   

Eurybia eryngiifolia 
Apalachicola National Forest
July 2014

Bristly heads and leaves of Eurybia eryngiifolia

                                                                                                                     












Thistle-leaved Aster (Eurybia eryngiifolia) is nearly endemic to the Florida panhandle, just barely extending into adjacent Georgia & Alabama. It is another pine flatwoods & fire-adapted species, closely associated with longleaf pine.  The scientific epithet (eryngiifolia) is a clear reference to the vegetative similarity to Rattlesnake Master (Eryngium yuccifolium)

Green Silky Scale

Green Silky Scale (Anthaenantia villosa) is a southeastern coastal plain endemic grass species, ranging from eastern Texas to Florida and northward into NC.

A. villosa upright habit and dense, flowering panicle
Note charred longleaf bole and open wiregrass dominated habitat
Image date: Nov 06, 2012

In our area I have observed it only in recently burned longleaf-wiregrass habitats in the inner coastal plain and sandhills regions. Within these generally dry, deep sandy soil sites, the grass occurs in gentle depressions (sometimes called "bean dips") or gentle, almost imperceptibly subtle slopes which are slightly moister than the surrounding uplands.

It occurs in dense swards of grasses where it can be easily overlooked unless flowering. Like a number of other species in these habitats, it may only flower (or at least most profusely) the growing season immediately after burning and may increase as a result. Kush et al. 2000 (in Alabama longleaf pine) documented much greater frequency for this species in biennially burned stands as compared to unburned stands with the greatest frequencies in summer and winter burn units.

Green Silky Scale (foreground), amidst dense wiregrass (Aristida stricta)
Sampson Co., NC (October 20,2011)

Silky Scale clumps turning color in Fall
Nov 06, 2014

                                                                       

Silky scale develops small rhizomatously spreading clumps which appear to expand slowly. Basal leaves are narrow, smooth, and tapering to a narrow tip. According to Grelen & Duvall (1966) leaves are nutritious and palatable forage.

Inflorescences form tight, narrow panicles on upright stems (maybe 3.5' tall) late in the growing season. Individual spikelets are densely pubescent and tightly packed along the upper 8 or so inches of the stem (See image right).

References:

Grelen and Duvall 1966, Common Plants of Longleaf Pine - Bluestem Range, Southern Forest Experiment Station Publication

Kush, J.S., R.S. Meldahl, and W.D. Boyer. 2000. Understory Plant Community Responseto Season of Burn in Natural Longleaf Pine Forests. Tall Timbers Fire Ecology Conference 21:33-39

Flooded Pitchers

                                                                                              

Top Image: Mountain Sweet Pitcher (Sarracenia jonesii), Small tubes completely underwater, larger tubes barely emergent

Bottom Image: Purple Mountain Pitcher (Sarracenia purpurea var. montana) , Large rosette completely submerged by flowing water.. 

Both images taken October, 14, 2014.

Previous posts have introduced these Pitcher Plants, which occur on frequently saturated "boggy" substrate. I imagine they are rarely submerged, however, these images document this can happen. This Fall (October 2014), the site experienced a heavy rainfall (approximately 6"), causing an adjacent stream to spill over its banks and directly impact some individuals of both species. Surface water levels receded quickly and the next day there was no standing water remaining.

Both are important conservation targets due to their localized distributions, restricted habitat, very limited numbers of known populations and inherent risk for extirpation. Gaining a better understanding of the hydrology of occupied and historic sites may help us determine ways to permanently protect, and ultimately increase the populations.