Saturday, October 3, 2015

A species that matters - Cuphea viscosissima

Blue Waxweed or Clammy Cuphea (Cuphea viscosissima) is infrequently encountered in North Carolina. It has been reported from the northern mountains, southern mountains, and northern Piedmont - perhaps it is overlooked and unreported at stations in between?  The species is widely distributed in neighboring states to the north and west, but is apparently most common in Missouri and southern Illinois.
Clammy Cuphea (Cuphea viscosissima): perimeter of Mt. Vernon Prairie, MO (08/21/15)

One of the most interesting traits of Blue Waxweed is the abundance of sticky hairs (shown above) which are thought to serve as defense against insect pests. Several years ago I noticed this adaptation in action. A grasshopper had landed on a Cuphea stem presumably to feed but ended up stuck by its front and hind legs (see below). At the time, the grasshopper was alive and well. Perhaps it would have eaten its way free, or perhaps eventually succumbed? Either way, evolution was thwarted when I felt a bout of compassion and flicked the grasshopper free.

Grasshopper stuck on Blue Waxweed (Durham Co, NC - 9/27/11)

Plant conservationists are often expected to justify saving native plants, with the implication that each species must stand on merits that we can measure.  To many, an otherwise obscure and insignificant species (like Blue Waxweed) only really "matters" if it holds the cure for cancer, or provides some other potential human benefit. When the utilitarian argument is needed it comes in handy to have a couple local, supporting examples.

Blue Waxweed serves admirably. Unexpectedly, Cuphea viscosissima produces some of the highest concentrations of capric acid among herbaceous plants (1).  Also known as a medium chain triglyceride, this type of "goat smelling" fatty acid has several commercial and industrial uses whose demand is growing exponentially worldwide. However, current supply comes almost exclusively from oil palms and coconut, creating a virtual "tropical oilseed monopoly" (2). Consequently, Blue Waxweed has been under consideration for massive production. One estimate suggests that 2.7 million hectares of Cuphea fields could supply North America and Europe's demand. I can only imagine!

Cuphea viscosissima in natural habitat, bordering sandstone glade in Missouri (8-18-2015)


Monday, September 28, 2015

The fatal flowers of Tall Thistle (Cirsium altissimum)

Tall Thistle (Cirsium altissimum); Durham Co, NC (9/14/15)

I find Tall Thistle (Cirsium altissimum) to be one of our most interesting natives.  Perhaps this is because I often root for the underdog, and so many gardeners, farmers, and even "conservationists" despise thistles. Hopefully their aversion may change if they come to understand the wildlife uses of native thistles and more particularly the benefits for native bees and butterflies. A fairly impressive, preliminary list of these has been documented using Tall Thistle, including over 20 native bees and nearly as many butterflies (1)

Hummingbird Clearwing Moth (Hemaris thysbe) visiting Tall Thistle; Durham Co, NC (9/14/15)

Tall Thistle occurs widely across the eastern US, from the prairie regions eastward, but is largely absent from the southeastern coastal plain. In North Carolina it has been reported mainly from western Piedmont and mountain counties; Durham County appears to be the easternmost location in the state.

Predominately white flowering Cirsium altissimum with a scattering of pink flowers  (Durham Co, NC - 9/14/15)

The majority of plants I have seen in North Carolina flower white, with a lesser intermixing of pink flowers (elsewhere in the range flowers seem to be more typically pink or purple and less commonly white). Tall Thistle is "monocarpic" meaning individual plants die shortly after flowering and setting seed (the classic case of monocarpism is the Century Plant). Cirsium altissimum is sometimes listed as biennial, but one group of authors (2) documented individual plants taking up to 4 years to emerge from young rosettes (such as the one shown below) into flowering stems.

Densely pubescent leaves of C. altissimum

In comparison to most thistle species, Cirsium altissimum has relatively soft and prickle-free leaves. Lower leaf surfaces are covered with dense white pubescence and stems are obviously hairy to the naked eye. Large leaves, a foot or more long, may develop on heavily shaded plants (see below). Some flowering stems exceed 10' in height and most produce multiple blooms.

Large shade leaves of C. altissimum, almost free of thorns

The large natural range of Tall Thistle and frequent occurrence in many regions suggest this is not, generally, a species whose survival we would need to be overly concerned about. HOWEVER, in a strange twist of fate, Tall Thistle may now be threatened by efforts in Midwestern prairie regions to eliminate truly problematic and invasive thistle species. A "bio-control" agent (weevil) deliberately introduced to control non-native thistles actually uses Tall Thistle "as frequently and intensively as it uses the targeted, exotic host plant" (3).

Cirsium altissimum seems to thrive only in relatively open habitats.  Ironically, the site where Tall Thistle occurs in Durham Co, NC also happens to be both nutrient rich and moist, creating growing conditions very conducive to dense woody plant growth. This apparent conundrum seems to suggest, at least in our area, that Tall Thistle requires regular disturbance and is likely another in the growing list of fire benefiting species. In fact, the currently large Durham population only appeared after burning. Thus far, we have been able to keep a portion of the site open with a combination of prescribed fire, selective chainsaw removal of trees, and invasive plant control.

Tall Thistle (Cirsium altissimum) flowering in open, "savanna"; Durham Co, NC (9/25/15)


Saturday, September 26, 2015

Mountain Bog Recovery & Expansion

Bog edge, before thinning (June 2015)
Bog edge, after thinning (July 2015)

The above images were taken near the perimeter of a so-called "mountain bog" in western North Carolina.  The first image shows the conditions before active restoration, the second image shows the same locale after clearing dense rhododendron invasion.  The only evident trees in the initial image are red maple and a lone pitch pine (Pinus rigida). After clearing the dense brush, a number of previously hidden stems of Pitch Pine in the heart of the wetland become apparent. The images also document (especially the second one) a small tributary creek feeding into the site from a black plastic culvert. Hugging the margin of this tributary (just past the lone pitch pine) is a grove of pitcher plants (see image below). 

Numerous pitcher plants (Sarracenia jonesii) hiding in this dense herbaceous foliage
At one time other rare plants were apparently present here when the creek was able to fan out gradually across the area, and the site was more open. However, years ago a road was constructed through the edge of the wetland. Several feet of fill material buried portions of the wetland, and altered the hydrology in some subtle and not so subtle ways (plans are in the works to remove the offending road section and culvert in hopes of restoring more natural water flows and reopening original wetland surface area for bog plants, stay tuned!). The dense thicket of shrubs that developed along the altered stream course excluded nearly all ground layer plant diversity directly underneath. In addition, the thick wall of green created both a sun and rain shadow across the nearby pitcher plants (these pitchers thrive in open sun, in saturated soils).   

Bog edge, before Rhododendron removal (June 2015)
Bog edge, after Rhododendron removal (July 2015) 

Numerous studies have shown that canopy vegetation can intercept and effectively remove up to 50% of seasonal or annual rainfall (Carlyle-Moses and Gash 2011, Forest Hydrology and Biochemistry). In contrast to deciduous plants, the evergreen rhododendrons continue to intercept rainfall all year long. At this site, the result could be losses of as much as 30" of water recharge per year! By removing the wall of rhododendrons we hope to create more open, sunlit conditions and add water back into the wetland system.  

Pile of Rhododendron previously removed from interior and margins of bog

We have been working on this restoration for several years, having been slowed mainly by lack of funding and resources to complete the task; the Friends of Plant Conservation ( has recently established a means by which people can support this effort. 

Mountain Bog interior conditions in 2011, before restoration, note forked pine tree

Mountain bog conditions in 2014 after interior brush removal, note forked pine
Elsewhere on this blog I have discussed a few of the rare plants whose populations have begun to rebound due, in part, to these restoration efforts.  Won't you help this progress continue?

Saturday, September 12, 2015


American Bluehearts (Buchnera americana) @ Taberville Prairie, Missouri (8-19-15)
I came across a few individuals of American Bluehearts (Buchnera americana) during recent explorations of the tallgrass prairie. According to Bruce Sorrie and Alan Weakley I was in the "heart of the range" for the species. Back home in North Carolina American Bluehearts is considered an endangered species and is believed to have been lost from nearly every location from which it has been documented. This made finding a few plants feel even more special even if they aren't so rare out in Missouri.  

Savanna Bluehearts (Buchnera floridana); Boiling Spring Lakes Plant Conservation Preserve, Brunswick Co, North Carolina (6-03-15)

Bluehearts was perhaps first documented in Carolina by Reverend Moses Ashley Curtis. In his "Catalogue of the Indigenous and Naturalized Plants of the State" (published in 1867 at the "N.C. Institution for the Deaf, and Dumb and the Blind"), Curtis provided no clues about the abundance of American Bluehearts but listed it only in the "Mid. and Up. Districts", regions most often referred to as the Piedmont and Mountains today. We now recognize an additional Buchnera species found in the coastal plain region as well, Savanna Bluehearts (Buchnera floridana) (see image above).  In contrast with American Bluehearts, Savanna Bluehearts characteristically has fewer and more compact flowers (although taxonomic treatments by Bruce Sorrie emphasize leaf characters to distinguish the two). There are some indications that Savanna Bluehearts may be pretty rare in North Carolina (although comprehensive data are lacking since it is not currently tracked by our Heritage Program). 

Buchnera sp. perhaps intermediate in some characters between B. americana and B. floridana?
St. Marks NWR, Northern Florida (7-05-14)

Savanna Bluehearts don't seem to occur further north than North Carolina, but rather extend southward across parts of the southeastern coastal plain, and may not extend beyond the coastal plain. American Bluehearts is primarily centered in Kansas, Oklahoma, and Missouri with spotty occurrences elsewhere, including into the northeast and to the edge of Lake Huron.  The ranges of the two species may overlap, but the extent to which this happens, especially the mid-south and parts of the southeast, remain unclear (at least to me) (see image above). Part of the reason the distribution and status of both species is uncertain is due to the fact that the two names are considered synonymous in many areas. For example, NatureServe lumps them together and therefore believes the combined entity is perhaps globally secure.  However, American Bluehearts have apparently been extirpated from several states and are considered quite rare or vulnerable in a significant number of others. If the populations consisting of Savanna Bluehearts were seperated from the tally, both species could turn out to be important elements of conservation concern.  

American Bluehearts amidst dense grass cover in tallgrass prairie remnant @ Taberville Prairie, Missouri

In the so-called heart of the American Bluehearts range, where I observed it, the species was found in "tallgrass prairie". Today, there are mere remnants of this once vast ecosystem that the US Fish & Wildlife Service ( believes has become "functionally non-existent over the last 150 years".   In my recent forays in Missouri prairies, I encountered American Bluehearts only in 2/20 + remnants visited and found < 5 individuals at each (although my observations were not systematic or comprehensive).  Savanna Bluehearts seems to have occupied longleaf pine savannas which could be considered ecologically analagous to tallgrass prairie, and has suffered a similar fate. Importantly both habitats were once subject to frequently recurring fires that likely benefit both Buchnera species.  A large part of the conservation challenge ahead will be to ensure that sufficient high-quality habitat remnants of both ecosystem are protected from ongoing threats and are adequately fire managed.   

Sunday, September 6, 2015

Tallgrass Vignettes

Standing amidst this sward of tallgrass prairie in Southern Kansas one evening (08-22-15) brought this line from Willa Cather to mind: ".......I felt the grass was the country, as the water was the sea."

Sweet Coneflowers (Rudbeckia subtomentosa) @ Osage Prairie, Missouri (8-19-15)
Profusion of Flowering Spurge @ Linden's Prairie, Missouri (8-20-15)

A few stalks of flowering Big Bluestem (Andropogon gerardii) stand above patches of Flowering Spurge (Euphorbia corollata) and a few other species @ Paintbrush Prairie, MO (8-16-15)

Stiff Sunflower (Helianthus pauciflorus) patch @ Tallgrass Preserve, Kansas (8-16-15)

Big Bluestem flowering above Flowering Spurge, Rosinweed stem on the left @ Tallgrass Preserve, Kansas (8-16-15)
Ashy Sunflowers (Helianthus mollis) @ Paintbrush Prairie, Missouri (8-17-15)

Flowering assemblage with Blue Sage (Salvia azurea), Ironweed, and Goldenrods @ Taberville Prairie, Missouri (8-18-15)

Getting on to evening at Golden Prairie, Missouri (8-22-15)

Tuesday, July 14, 2015

Golden Crest (Lophiola aurea) - Coastal Plain Endemic with strange "disjunct" distribution

Lophiola aurea, Brunswick Co, North Carolina
June 3, 2015

Golden-Crest (Lophiola aurea) is endangered in North Carolina where it is known from only a handful of sites in the extreme southeastern coastal plain. The species is entirely absent from adjacent states of South Carolina and Virginia but populations reappear both further north and south, The nearest populations to the south occur in south-central Georgia, a disjunction of approximately 440 miles!  From there, Lophiola's known distribution (based on USDA PLANTS database) skips over another approximately 140 miles before re-appearing in the panhandle of Florida (where it seems to be most widespread), and adjacent Alabama and southern Mississippi. Interestingly, another widely disjunct population has been reported in western Louisiana. To the north, the species re-appears in New Jersey and a few points beyond including Nova Scotia!  These northern populations may be the most unexpected.  To quote G.E. Nichols (Rhodora 1919), "Lophiola aurea in Nova Scotia. Surely there must be a mistake".  But no occurs there along with a number of other disjunct populations of typically southeastern US coastal plain species.

Lophiola aurea population in Brunswick Co, NC
(dark shadow on left is dense woods)

Back in North Carolina, the small population shown here (left) was holding on at the very edge of a power-line clearing. Maintenance activities and off-road vehicles had torn up much of the adjacent ground while the surrounding woods appeared to be too dense and overgrown (unburned) to support the plant.

Last summer I observed Lophiola in all its glory in an open pine savanna in north Florida. It's almost embarrassing how much time I spent watching small bees visit the tiny (~ 10mm wide) flowers. Since I did, I'll include a few images here:
Lophiola aurea pollinator, south of Tallahassee Florida
July 5, 2014

I'd be interested to know what species this little bee is, and whether or not it occurs throughout Lophiola's highly fragmented range.

Sunday, July 12, 2015

Oh Dread! Another Naturalized Exotic Plant?

Driving down the highway along the Northeast Cape Fear River near Wilmington recently, I caught a glimpse of the plants shown above.  The 5-6' tall plants with bright yellow flowers were unfamiliar so I risked life and limb and pulled a U-turn on the heavily traveled road to take a closer look.

Ludwigia bonariensis, near Eagle Island, NC
July 7, 2014

The plants were incredibly attractive and intriguing.  I concluded they were most likely Ludwigia bonariensis.  I was excited by the comment in the Manual of Vascular Flora of the Carolinas which listed it as "very local; Brunswick and New Hanover cos." --- this thing was rare!

But then I got confused!

A later check of Godfrey & Wooten (Aquatic & Wetland Plants of the Southeastern United States) listed it as  "Local, s.e. N.C.; Fla." but added, "native of Trop. Am." --- this thing was exotic!

Weakley's Flora stated it is "apparently native of tropical America" and suggested it may have been introduced on ship's ballast, while noting our plants appear to differ somewhat from specimens elsewhere.

NatureServe considers it exotic in NC, SC, and AL, but lists it as "critically imperiled" in Arkansas. Also of interest is the common name used by NatureServe; "Carolina Seedbox" - an odd name for something from the tropics.

USDA Plants lists it as native in NC, SC, AL, and FL and doesn't record it all from Arkansas.

Both USDA Plants and NatureServe omit the record that showed up in an artificially created wetland in VA around 10 years ago....

My head is humming and it won't go - in case you don't know.....

Ludwigia bonariensis sepals and capsules, just west of Wilmington, NC


Monday, May 25, 2015

Piedmont Savanna Restoration @ Hebron Road

STAR indicates Preserve location,
ARROWS point to surrounding "urban interface"
                                                        The Hebron Road Plant Conservation Preserve, in the Piedmont of North Carolina, is actively managed with the goal of restoring open, savanna-like habitats and a naturally-occurring suite of rare plants. At this site in particular this goal poses many management challenges.  The site is ringed by development including well traveled roads, an elementary school, and a massive subdivision. All these factors make prescribed burning difficult.  
Evening prescribed Burn conducted March 29, 2012
North Carolina has smoke management guidelines that must be followed when conducting prescribed burns.  Our site has a very narrow set of conditions under which it can be burned, meaning only a few days are available each year.  In order to capitalize on one of these infrequent events, in 2012 we burned at dusk, with direct input from the National Weather Service.

4/10/2015 after most recent prescribed fire.
Redbud (Cercis canadensis) and Dogwood (Cornus florida) flowering in background
Brown unburned patches are mostly Indiangrass (Sorghatrum nutans)

The site was burn again in Spring 2015 (regular fires are needed to control woody plant growth, encourage flowering of rare perennials, create seedbeds for germination, etc).  Like many other "growing season" burns, the fire did not consume the undergrowth entirely across the the site.  The most open, grassy areas burned less completely than those where hardwood leaf litter predominated.
Last year's growth of Smooth Coneflower (Echinacea laevigata) stands tall in one of the unburned patches (4/10/15)

4/19/2015 regrowth of Ironweed (Vernonia sp) after prescribed fire. 

The Preserve was established to protect a remnant population of the federally endangered Smooth Coneflower (Echinacea laevigata). When acquired, all the Coneflower stems were found along the roadside.  Slowly, but surely the population continues to expand at the site. Importantly many of the current plants are now found further away from the roadside and the threats that come with it.

 (left): Vigorous patch of Smooth Coneflowers (06/11/14) established from seed collected on-site. Boulders of diabase rock are present.

E. laevigata seedling sprouting after fire (04/07/15)
Narrow-leaf Aster (Symphyotrichum laeve var. concinnum)
seedling sprouting after fire (4/07/15)

Several other rare plants found on the Preserve also appear to benefit from the restoration and management activities. The Narrow-leaf Aster (Symphyotrichum laeve var. concinnum), listed as Threatened in North Carolina and known from only a handful of sites in the Piedmont, is expanding. 

Narrow-leaf Aster (Symphyotrichum laeve var. concinnum)
Fall flowering, Durham Co, NC (10/10/11) 
Erect Bindweed (Calystegia spithamea)
Spring flowering, Durham Co, NC (05/14/15)
Erect Bindweed (Calystegia spithamea), considered a "watch list" species in NC, occurs at the Preserve at what appears to be the easternmost location documented in North Carolina.  This low growing species doesn't appear to compete well as vegetation becomes taller and more robust in the absence of fire. Another rare plant found on the site, Prairie Dock (Silphium terebinthinaceum), also reaches its approximate eastern occurrence in North Carolina here and thrives with fire. I previously discussed this species

Prairie Dock sprouting after spring fire@ Hebron Road Preserve

Prairie Dock flowering @ Hebron Road Plant Conservation Preserve
Fall Flowering (8/23/14)