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)

References:
(1) http://illinoiswildflowers.info/flower_insects/plants/tall_thistle.htm
(2) http://www.esajournals.org/doi/pdf/10.1890/ES11-00096.1
(3) http://www.researchgate.net/publication/26278359

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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 mistake...it 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.

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Plum Thicket Part 1, American Plum

American Plum flowering amidst Eastern Red Cedar, and open grassland
Durham Co., NC April 15, 2015

American Plum (Prunus americana) occurs in scattered localities across the North Carolina Piedmont & Mountains but is generally absent or infrequent in the coastal plain.  Wide ranging across North America, it may have been cultivated by some Native Americans (see Havard 1895 in Bulletin of Torrey Botanical Club)

Showy, white, highly aromatic flowers develop before the leaves, and before most other deciduous species have leafed out in our area.

American Plum thicket of dense sprouts
invading a frequently burned "prairie-like" habitat

Small American Plum tree

American Plum tree with drooping branches
Note the sparse vegetation underneath vs.
dense grass growth outside

American Plum is infamous for forming dense thickets in certain open habitats. These thickets are due, in part, to its propensity to root sprout.  In the example shown here, sprouts are 3-5' tall and leafed out more fully than nearby mature trees, but no flowers were produced. Most have developed 10' or more from the main trunk and appear to be "invading" the open area, with the shortest sprouts along the leading edge.






The origin of these sprouts appear to be large Prunus americana individuals with well developed, widely spreading, and drooping branches, above twisted,multi-trunked stems. These small trees (see images following) produce significant masses of flowers. Interestingly, the space around the trunk(s) is clear of sprouts and other woody plants, possibly due to the density of the canopy or the species may be allelopathic.

The following sequence illustrates progressive stem development.   

Prunus americana sprout elongating above surrounding stems
Note resemblance to brambles or rose canes (to which they are related) 

Prunus stem undergoing height & diameter growth,
developing vertical dimension, showing well developed spur shoots

Small diameter tree with splitting bark, few shoots emerging directly from trunk

American Plum with massive (for the species) triple trunk

Progression of American Plum sprouts to trees,
with small sprouts (left), small tree flowering (middle), large flowering tree (right)

Well-formed & floriferous American Plum
Durham County, April 08, 2015

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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:

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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

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Florida Paspalum - Where o where has it gone?

Florida Paspalum with stigmas and anthers (9/07/14)

Florida Paspalum (Paspalum floridanum) is one of our premier native, warm season grasses. Tall & robust, reaching heights of ~ 5 ', it produces large mature spikelets and seeds. These seeds are (or were) important food sources for quail, doves, and turkeys (Grelen and Duvall 1966).

Ranging throughout most of the lower eastern US, Florida Paspalum occurs and occasionally becomes dominant in a range of high quality, remnant habitats. A few of these include:

• Florida dry prairies (Orzell & Bridges 2006) 
• Texas Blackland prairies (Collins et al. what date), 
• Arkansas & Missouri tallgrass prairies (Ruby 1953, Kelting 1982)
• Longleaf pine forests & savannas of Georgia (Drew etal. 198), se LA (Roth et al. 2008)) and east Texas (Phillips et al. 2007)
• Coastal or "cajun" prairies of south Louisiana  (Allen et al. 2001) 
• Calcareous prairies of Georgia (Echols & Zomlefer 2010), Mississippi (Campbell & Seymour 2011) and Louisiana (Allen et al. 2004)

In Illinois, Verts (1965) found that all (remaining) stands of P. floridanum occurred within 25 yards of railroad rights-of-way, suggesting the sorry state of prairie-like remnants in that state.

In the North Carolina Piedmont, I have observed this species in the only frequently burned longleaf pine forest remaining in the state (near Troy, NC) and in a few remnant burned woodlands near Durham, one of which has been burned biennially for 10 years. It is also found on open roadsides such as the one shown below.

Florida Paspalum (8-13-14) on floristically rich roadside remnant in Granville Co, NC

P. floridanum in biennially burned "savanna" (9/09/13)

                                       
At a distance, the young leaves often display a bluish cast, reminiscent of Rattlesnake Master (Eryngium yuccifolium).

This tall grass species occurs with the remnant & disjunct prairie flora under the power-lines known as Picture Creek Diabase Barrens where Stanley (2013) listed it as "infrequent".  Interestingly, P. floridanum is apparently absent from a number of sites where other major prairie grasses are found in the southern Piedmont (Tompkins et al. 2010a, Tompkins 2013), as well as the infamous Suther Prairie (Tompkins et al. 2010b). Perhaps most surprisingly, it was not identified in a recent floristic study of 31 "rural rights-of-way" across the Piedmont (Adams 2012), a study region which including the locations of the pictures included on this page.



As P. floridanum begins to bolt and flower, spikelets emerge seemingly from the midst of the main stem leaves. They eventually overtop the stems but remain tightly arranged around the main stem (left below), later developing much more spreading (3-7 or so) branches (right below).  

P. floridanum bolting (9-07-2014), some nearby inflorescences already spreading

Following images: (left): 8/13/14 Granville Co, NC, (right): 9/07/14 Durham Co, NC

                                                                                                                                                       

Paspalum floridanum spreading branches have begun to droop (8-23-14),
 note abundant bluish lower leaves in background

References:

Adams, N.S. 2012. A Synthesis of Rights-of-way Native Plant Communities: 
Identifying Their Relevance to Historical and Contemporary Piedmont Savannas. Unpublished MS thesis.
Allen C.M., S. Thames, and L. Chance, and C. Stagg. 2004. Proc. 19th North American Prairie Conference 19-22.
Allen C.M., M. Vidrine, B.Borsari, and L. Allain.  2001. Proc. 17th North American Prairie Conference 35-41.
Campbell, J.J.N., and W.R. Seymour. The Vegetation of Pulliam Prairie, Chickasaw County, Mississippi: a Significant Remnant of Pre-Columbian Landscape in the Black Belt. Journal of the Mississippi Academy of Sciences 56:248-263.
Collins, O.B., F.E. Smeins, D.H. Riskind. Plant Communities of the Blackland Prairie of Texas.
Drew, M.B. L. K. Kirkman, and A. K. Gholson.  The Vascular Flora of Ichauway, Baker County, Georgia: A Remnant Longleaf Pine/Wiregrass Ecosystem. Castanea 63: 1-24.
Echols, L, and W.B. Zomlefer. 2010. Vascular Plant Flora of the Remnant Blackland
Prairies in Oaky Woods Wildlife Management Area, Houston County, Georgia. Castanea 75:78-100
Grelen and Duvall 1966, Common Plants of Longleaf Pine - Bluestem Range, Southern Forest Experiment Station Publication
Kelting, R. W. 1982. The Wah-Sha-She Prairie near Asbury, Jasper County, Missouri. Proc. 8th North American Prairie Conference 80-83.
Orzell & Bridges 2006.  Floristic Composition of the South-Central Florida Dry Prairie Landscape.  Proceedings of the Florida Dry Prairie Conference.
Phillips, T.C., S. B. Walker, B.R. & M.H. MacRoberts. 2007. Vascular Flora of a Longleaf Pine Upland in Sabine County, Texas. Phytologia 89:317-338.
Roth, et al. 2008. How Important is Competition in a species rich savanna. Ecoscience; 94-100
Ruby, E.S. 1958. http://dante.ddns.uark.edu/aas/issues/1953v6/v6a8.pdf
Stanley, J. S. 2013. Guide to the Vascular Flora of Picture Creek Diabase Barrens (Granville County, North Carolina). Unpublished MS Thesis.
Tompkins, R.D., W.C. Stringer, K.H. Richardson, E.A. Mikhailova and W.C. Bridges, Jr. 2010a. Big Bluestem (Andropogon gerardii: Poaceae) communities in the Carolinas: Composition and ecological factors. Rhodora 112:378-395.

Tompkins, R.D., C.M. Luckenbaugh, W.C. Stringer,K.H. Richardson, E.A. Mikhailova and W.C. Bridges, Jr. 2010b. Suther Prairie: Vascular flora, species richness and edaphic factors. Castanea 75:232-244.

Tompkins, R.D. 2013. Prairie-relict communities of a Piedmont monadnock. Castanea 78:185-197.
Verts, B.J. 1965. Notes on the ecology of Paspalum floridanum in Illinois. American Midland Naturalist 73

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