Rhus michauxii - Sarg.
Michaux's Sumac
Other English Common Names: False Poison Sumac
Other Common Names: false poison sumac
Taxonomic Status: Accepted
Related ITIS Name(s): Rhus michauxii Sarg. (TSN 28787)
Unique Identifier: ELEMENT_GLOBAL.2.148771
Element Code: PDANA08070
Informal Taxonomy: Plants, Vascular - Flowering Plants - Sumac Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Sapindales Anacardiaceae Rhus
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Rhus michauxii
Taxonomic Comments: Distinct species.
Conservation Status
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NatureServe Status

Global Status: G2G3
Global Status Last Reviewed: 17Feb2006
Global Status Last Changed: 17Feb2006
Rounded Global Status: G2 - Imperiled
Reasons: Endemic to the inner Coastal Plain and lower Piedmont of Virginia, Georgia, and the Carolinas (a historic collection from Florida may have been a waif). Currently, the species is known from approximately 50 extant occurrences. In 1993 a large, prolifically fruiting population was discovered on U.S. Army lands in Virginia, and the Army is now actively protecting the plants. Most extant populations are now protected and managed for. Overall, however, the species has been in decline: in the 100 years following its discovery in 1895, half of all the historic occurrences were extirpated, largely due to habitat conversion to agriculture and other uses. These threats are ongoing as are threats from the nearly universal suppression of natural fires within this species' range, geographic fragmentation and isolation of small, single-sex populations, hybridization with other species, and the potential for accidental destruction of roadside and other vulnerably situated populations.
Nation: United States
National Status: N2

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Georgia (S1), North Carolina (S2), South Carolina (SX), Virginia (S1)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (28Sep1989)
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast

NatureServe Global Conservation Status Factors

Range Extent Comments: Rhus michauxii is a species which was historically endemic to the Inner Coastal Plain and lower Piedmont of North Carolina, South Carolina, and Georgia (USFWS 1989).

HISTORIC RANGE: From the time of its discovery in 1895 until 1989, half of the known occurrences of Rhus michauxii have been extirpated (USFWS 1989). Thirty-two occurrences were historically reported from 23 counties in NC, SC, and GA (USFWS 1989). Four occurrences historically known from Cobb, Columbia, Newton, and Rabun counties, GA, are believed extirpated (Murdock and Moore 1991, Patrick 1993). Historical collections are known from Florence, Kershaw, and Oconee counties, SC. Following extensive, unsuccessful searches of their last known locations, as well as other areas of suitable habitat, Michaux's sumac is believed extirpated from the state (USFWS 1989, Murdock and Moore 1991). Historical and/or extirpated NC records exist (year last seen in parentheses) for Durham (1949), Franklin (1914), Hoke (1981), Johnston (1833), Lincoln (prior to 1917), Mecklenburg (pre-1800s), Moore (1901), Orange (1964), Robeson (1982), Wake (1942), and Wilson (1958) counties (Murdock and Moore 1991, NCNHP 1993). Considered extirpated from Florida, where the the original collection was made in 1961 in Alachua County (Murdock and Moore 1991). Apparently by 1989 the collection site had been developed and was occupied by at least one residential home. Kathy Burkes of FNAI notes: "Whether the plants seen in 1961 were waifs carried far afield from the Piedmont by humans or other animals in "recent" times, or were true relicts of a former wide distribution reaching south into Florida is another question. We may never know for sure about that."

CURRENT RANGE: Extant occurrences are currently known to exist in North Carolina, Virginia, and Georgia. In NC, 44 occurrences (number of occurrences for each county follows in parentheses) are currently known from Cumberland (1), Davie (1), Franklin (1), Hoke (5), Moore (4), Richmond (18), Robeson (1), Scotland (8), and Wake (3) counties (NCNHP 2005). The range of this species in North Carolina, when calculated by minimum convex polygon, is approximately 290 km2.

In 1993, the Virginia Department of Conservation and Recreation's Division of Natural Heritage discovered a large population of Michaux's sumac on Fort Pickett Military Reservation in Dinwiddie and Nottoway counties, Virginia (Fleming 1993). By the end of inventory work in 1993, 32 subpopulations containing an estimated total of 20,000+ plants had been documented within approximately 10,000 acres (Fleming 1993). The largest of these more-or-less continuous subpopulations contained an estimated 10,000+ plants, and several others contained an estimated 1,000+ plants (Fleming 1993). It should be noted that at the time of the 1993 survey, plants were seen that were presumed to be a hybrid but by 1995, due to genetic research on Fort Pickett colonies (Burke and Hamrick 1995), it was decided that these plants with little to no stem pubescence but pubescent leaflets should be included under R. michauxii. Therefore the 1993 stem count total underestimates the true total. By 1995, an additional 65 subpopulations with at least 7500 stems were found within the occurrence area (Van Alstine and Smith 1995). Other populations recognized as separate occurrences were found on Fort Pickett by either DCR-DNH staff or Fort Pickett personnel adding 5 other occurrences totaling at least 250-300 stems and expanding the known occurrences south into Brunswick County. In 2003, consultants surveying an abandoned railroad track right-of-way for a proposed high speed rail line found the first occurrence in Virginia located outside of Fort Pickett. This population of 230 stems in Brunswick County occurs in a fairly ruderal habitat next to a railroad grade with trash and weeds. Three years of surveys (2003-2005) in areas surrounding Fort Pickett including public roadside utility line rights-of-way and roadsides and clearcuts on private lands have been unsuccessful in finding any more occurrences (Van Alstine and Belden 2005, N. Van Alstine 2006). The current range extent in Virginia occupies ca. 87 km2, determined using a minimum convex polygon.

In Georgia both extant and historical populations of R. michauxii occur on mafic/sub-mafic substrates and derivatives. This type of habitat in GA is extremely limited.

Area of Occupancy: 1-25 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 21 - 80
Number of Occurrences Comments: About 50 extant occurrences. Most are located in North Carolina; the largest single occurrence is in Virginia.

Population Size Comments: The number of stems rangewide is estimated at 89,000 - 96,000 but given the clonal nature of the species, the actual number of genetically distinct individuals is likely far lower than the number of stems present.

Number of Occurrences with Good Viability/Integrity: Some (13-40)
Viability/Integrity Comments: About 13 occurrences with excellent/good viability. North Carolina has 12 occurrences with excellent/good viability. Virginia has 1 extremely large occurrence containing in the neighborhood of 27,500 ramets mostly within good quality habitat largely maintained by fires created by military training exercises; 2 others are considered only "fair." Georgia has only 2 extant occurrences , one where the species was reintroduced in 1990 at a former site where it had been extirpated by residential development (with about 40 ramets, all female), and another population suffering from fire suppression and woody competition (5-10 ramets, all male).

Overall Threat Impact: High - medium
Overall Threat Impact Comments: Two major threats to Rhus michauxii are degradation of habitat due to lack of disturbance, and low reproductive capacity resulting from the geographic isolation of small single-sex populations (USFWS 1990).

Michaux's sumac is a shade-intolerant species which declines when its habitat becomes fire suppressed and a dense overstory develops. Since the early part of the 20th century, natural fire regimes have been virtually eliminated within its range as a result of landscape fragmentation and active fire suppression. This has led to an obvious decline in Rhus michauxii habitat. Many of the remaining Rhus michauxii populations are in sites that are cleared artificially (Center for Plant Conservation 2002).

From a reproductive standpoint Rhus michauxii is threatened in several ways. Many populations do not contain plants of both sexes (USFWS 1990). Partly because of its clonal nature and the geographic isolation of populations, Rhus michauxii also has low genetic variability compared to more widespread congeners (R. glabra and R. copallina) (Center for Plant Conservation 2002; Sherman-Broyles et al. 1992), which was determined through starch-gel electrophoresis. Yet when compared to other species with similar life history characteristics R. michauxii has similar genetic diversity values. Sherman-Broyles et al. (1992) also noted that the reduced amount of genetic variation may also be due to small population sizes, restricted distribution, and lower clonal diversity. However, the effect of low levels of genetic diversity on the survival of this species on an evolutionary time-scale has not been determined. Another characteristic impacting the genetic integrity of Rhus michauxii is that it may hybridize. Rhus michauxii hybridizes with Rhus glabra forming Rhus x ashei (Patrick et al. 1995). Hybrids have been discovered at two sites which were known to previously support Rhus michauxii (Hardin and Phillips 1985 in USFWS 1990).

There are plans by the Georgia Plant Conservation Alliance to introduce plants of the opposite sex into the two single sex Georgia populations. There are also plans to introduce fire and reduce woody competition at one of the sites. A third "safeguarding" site on protected Georgia Dept. of Natural Resources property may also be established.

Rhus michauxii is also threatened by conversion of habitat for agriculture, silviculture, commercial and residential development, road construction and improvements. The majority of historic sites were lost due to land development, and many of the current populations are facing the same threat. In North Carolina, these threats are of primary concern as areas near Rhus michauxii populations are urbanized; several occurrences have the potential to be impacted by North Carolina Department of Transportation road widening projects.

Other threats include trampling due to timber harvesting or mechanized military training activities, herbicide drift due to the proximity of populations to managed rights-of-way, and fungal disease and stem borers which attack plants (Bucher 1993). Rust fungi appear worse during wet summers, and low genetic diversity within populations may make them very susceptible to extirpation by disease (Bucher 1993).

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: Declines may be continuing (since 1895, half of the known populations have been extirpated). In North Carolina, reports from several occurrences located in rural settings note the presence of woody vegetation encroaching into Rhus michauxii sites. Without active management, the viability of such occurrences will undoubtedly continue to decline. Though many occurrences are protected on military reservations, impact from mechanized military training activities may be occurring. The resilience of the species to these impacts has not been documented. In Virginia the short term trend is unknown due to lack or recent monitoring and lack of knowledge about the history of the distribution of the species outside of Fort Pickett. It is possible that once-small colonies that predated the military training activities that promote fire at Fort Pickett have expanded with the increase in ordnance-caused fires. It is known that the area of one colony at Fort Pickett was destroyed during expansion of a range and the plants were removed and transplanted into the area of a known colony elsewhere on Base (Emrick 2003).

Long-term Trend: Decline of 30-50%
Long-term Trend Comments: Has disappeared (or is disappearing) from the southern half of its range. However, the long term trend in Virginia is unknown; it may well be that in Virginia Rhus michauxii has increased there over the past 200 years.

Environmental Specificity: Very narrow. Specialist or community with key requirements scarce.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Rhus michauxii is a species which was historically endemic to the Inner Coastal Plain and lower Piedmont of North Carolina, South Carolina, and Georgia (USFWS 1989).

HISTORIC RANGE: From the time of its discovery in 1895 until 1989, half of the known occurrences of Rhus michauxii have been extirpated (USFWS 1989). Thirty-two occurrences were historically reported from 23 counties in NC, SC, and GA (USFWS 1989). Four occurrences historically known from Cobb, Columbia, Newton, and Rabun counties, GA, are believed extirpated (Murdock and Moore 1991, Patrick 1993). Historical collections are known from Florence, Kershaw, and Oconee counties, SC. Following extensive, unsuccessful searches of their last known locations, as well as other areas of suitable habitat, Michaux's sumac is believed extirpated from the state (USFWS 1989, Murdock and Moore 1991). Historical and/or extirpated NC records exist (year last seen in parentheses) for Durham (1949), Franklin (1914), Hoke (1981), Johnston (1833), Lincoln (prior to 1917), Mecklenburg (pre-1800s), Moore (1901), Orange (1964), Robeson (1982), Wake (1942), and Wilson (1958) counties (Murdock and Moore 1991, NCNHP 1993). Considered extirpated from Florida, where the the original collection was made in 1961 in Alachua County (Murdock and Moore 1991). Apparently by 1989 the collection site had been developed and was occupied by at least one residential home. Kathy Burkes of FNAI notes: "Whether the plants seen in 1961 were waifs carried far afield from the Piedmont by humans or other animals in "recent" times, or were true relicts of a former wide distribution reaching south into Florida is another question. We may never know for sure about that."

CURRENT RANGE: Extant occurrences are currently known to exist in North Carolina, Virginia, and Georgia. In NC, 44 occurrences (number of occurrences for each county follows in parentheses) are currently known from Cumberland (1), Davie (1), Franklin (1), Hoke (5), Moore (4), Richmond (18), Robeson (1), Scotland (8), and Wake (3) counties (NCNHP 2005). The range of this species in North Carolina, when calculated by minimum convex polygon, is approximately 290 km2.

In 1993, the Virginia Department of Conservation and Recreation's Division of Natural Heritage discovered a large population of Michaux's sumac on Fort Pickett Military Reservation in Dinwiddie and Nottoway counties, Virginia (Fleming 1993). By the end of inventory work in 1993, 32 subpopulations containing an estimated total of 20,000+ plants had been documented within approximately 10,000 acres (Fleming 1993). The largest of these more-or-less continuous subpopulations contained an estimated 10,000+ plants, and several others contained an estimated 1,000+ plants (Fleming 1993). It should be noted that at the time of the 1993 survey, plants were seen that were presumed to be a hybrid but by 1995, due to genetic research on Fort Pickett colonies (Burke and Hamrick 1995), it was decided that these plants with little to no stem pubescence but pubescent leaflets should be included under R. michauxii. Therefore the 1993 stem count total underestimates the true total. By 1995, an additional 65 subpopulations with at least 7500 stems were found within the occurrence area (Van Alstine and Smith 1995). Other populations recognized as separate occurrences were found on Fort Pickett by either DCR-DNH staff or Fort Pickett personnel adding 5 other occurrences totaling at least 250-300 stems and expanding the known occurrences south into Brunswick County. In 2003, consultants surveying an abandoned railroad track right-of-way for a proposed high speed rail line found the first occurrence in Virginia located outside of Fort Pickett. This population of 230 stems in Brunswick County occurs in a fairly ruderal habitat next to a railroad grade with trash and weeds. Three years of surveys (2003-2005) in areas surrounding Fort Pickett including public roadside utility line rights-of-way and roadsides and clearcuts on private lands have been unsuccessful in finding any more occurrences (Van Alstine and Belden 2005, N. Van Alstine 2006). The current range extent in Virginia occupies ca. 87 km2, determined using a minimum convex polygon.

In Georgia both extant and historical populations of R. michauxii occur on mafic/sub-mafic substrates and derivatives. This type of habitat in GA is extremely limited.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States GA, NC, SCextirpated, VA

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
GA Chattahoochee (13053)*, Cobb (13067), Elbert (13105), Fulton (13121), Muscogee (13215)*, Newton (13217), Rockdale (13247)
NC Cumberland (37051), Davie (37059), Durham (37063), Franklin (37069), Hoke (37093), Mecklenburg (37119), Moore (37125), Nash (37127), Richmond (37153), Robeson (37155), Scotland (37165), Union (37179)*, Wake (37183), Wilson (37195)*
SC Kershaw (45055)*, Richland (45079)*
VA Brunswick (51025), Dinwiddie (51053), Nottoway (51135)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Nottoway (03010201)+, Upper Tar (03020101)+, Upper Neuse (03020201)+, Contentnea (03020203)+, Upper Cape Fear (03030004)+, Upper Yadkin (03040101)+, Lower Pee Dee (03040201)+, Lumber (03040203)+, Little Pee Dee (03040204)+, Upper Catawba (03050101)+, Lower Catawba (03050103)+*, Wateree (03050104)+*, Congaree (03050110)+*, Broad (03060104)+, Upper Ocmulgee (03070103)+, Upper Chattahoochee (03130001)+, Middle Chattahoochee-Walter F. George Reservoir (03130003)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A low-growing, densely hairy, dioecious shrub, mostly 0.3 to 0.6 m tall. Leaves are pinnately compound with 7-13 leaflets that are coarsely toothed. Female plants produce erect clusters of greenish-yellow to white 4-5 parted flowers and conspicuous red drupes. Flowers from April to June. Fruits persist from August through September or October.
Diagnostic Characteristics: Rhus michauxii is distinguished from other Rhus species by its small stature (mostly 0.3 to 0.6 m tall), 7-13 leaflets, and its overall pubescence (both the leaves and the stems are densely pubescent). In addition, the leaf rachis is often winged at the terminal portion of the leaf (Patrick et al. 1995; Weakley 2004). For a technical description see Radford et al. (1968).
Duration: PERENNIAL, DECIDUOUS
Reproduction Comments: Many populations do not contain plants of both sexes (USFWS 1990).
Ecology Comments: Fire or some other suitable form of disturbance, such as mowing or careful clearing, appears to be essential for maintaining the open habitat preferred by Rhus michauxii. Without such periodic disturbance, this type of habitat is gradually overtaken and eliminated by the shrubs and trees of the adjacent woodlands. As the woody species increase in height and density, they overtop the Rhus michauxii, which is shade-intolerant.
Terrestrial Habitat(s): Forest/Woodland, Woodland - Mixed
Habitat Comments: Michaux's sumac occurs in sandy or rocky open woods, sometimes in association with circumneutral soils (USFWS 1990). In the fall line sandhills region it occurs in submesic loamy swales. In the eastern Piedmont, it occurs on sand soils derived from granite. In the central Piedmont, it occurs on clayey soils derived from mafic rocks (Weakley 2004). In all of its habitats, Rhus michauxii is dependent upon some form of disturbance to maintain the open quality of its habitat (USFWS 1989). Periodic, naturally occurring fires provided such disturbance historically. Today, however, many of the Michaux's sumac occurrences are in areas that are artificially disturbed, such as highway and railroad rights-of-way, pine plantations, edges of cultivated fields, and other cleared lands (USFWS 1989, TNC 1991-93, NCNHP 1993, Center for Plant Conservation 2002).

Although roadside occurrences appear to be thriving in the presence of some level of disturbance (i.e., mowing), they are always under the constant threat of catastrophic disturbance. Roadbed widening or heavy equipment activity on cleared lands, for example, may dramatically reduce the number of individuals. These reductions, if they come at a crucial stage in the species' reproductive cycle (i.e., during flower or fruit production), could have severe long-term effects on the population. Although it appears that Michaux's sumac can rebound from large disturbances, it is not clear how much genetic diversity is lost with each disturbance.

In the North Carolina Sandhills region, naturally occurring Rhus michauxii appears to be restricted to slightly loamy, but still well- drained, sites which are scattered through longleaf pine/scrub oak/wiregrass woodlands. Loamy soil sites are usually found in slight depressions, swales, or along lower slopes and are quickly recognized by their high diversity of herbs, especially with regard to their high number of legume, composite and grass species. Associated species consistently found in these loamy sites are considered good "Rhus michauxii indicators" by Sandhills botanists and include Ceanothus americanus, Paspalum bifidum, Tridens carolinianus, Aristida lanosa, Onosmodium virginianum, and Helianthus divaricatus. These sites are also characterized by a higher frequency of mesophytic hardwoods, such as Cornus florida, Carya alba, and Quercus stellata, than surrounding, drier woodland areas.

Like all upland longleaf pine communities, this loamy swale community (classified as Pine/Scrub Oak Sandhill, loamy soil variant by Schafale and Weakley 1990) is fire-maintained. Natural fires, resulting from lightning strikes mainly in early summer, were believed to have occurred every three to seven years in upland areas of the North Carolina Sandhills (Schafale 1993). These episodic fires were important for reducing hardwood encroachment, recycling nutrients, and creating conditions necessary for the regeneration of longleaf pine, wiregrass, and associated herb species. Since the early part of the 20th century, natural fire regimes and processes have been virtually eliminated as a result of landscape fragmentation and active fire suppression. This has led to an obvious decline in Rhus michauxii habitat, and more than likely a dramatic decline in the number of occurrences.

Of notable exception to this trend are the lands on Fort Bragg, Camp MacKall, and Sandhills Game Land. These properties, which all support large occurrences of Michaux's sumac, have been managed (for various reasons) with prescribed burns since the 1960s. Prior to that time, these areas were periodically impacted by wildfires. Large sections of these properties have, therefore, never been fire-suppressed for extended periods of time (over 30 years), and it is likely for this reason that Michaux's sumac has survived there. A greater number of loamy sites and more and larger occurrences of Rhus michauxii are found on Sandhills Game Land than on Fort Bragg or Camp MacKall, all within close proximity to each other. This disparity may be explained by topographic differences. Loamy swales and depressions, while relatively uncommon on the more highly dissected and hilly terrain of Fort Bragg in Hoke and Cumberland counties, are common on the more gently rolling landscape of Sandhills Game Land in Richmond and Scotland counties. These depressions and swales can often be identified on topographic maps.

According to Weakley (1993b), in the Piedmont, Rhus michauxii historically occurred in both sandy, acidic soils and clayey, circumneutral soils on dry upland sites. Piedmont occurrences are in communities which formerly experienced frequent to occasional lightning-set fires. Fire, in combination with soil droughtiness, maintained open woodlands or oak savannas which provided suitable habitat for R. michauxii. Fire suppression in the Piedmont has been nearly universal and led to vegetative succession, eliminating R. michauxii to an even greater degree than in the Fall-line Sandhills and Inner Coastal Plain (Weakley 1993b).

The following discussion is from Fleming (1993): The recently discovered Fort Pickett occurrence is located well into the Virginia Piedmont on rolling, gently dissected uplands underlain by a granitic formation. The thriving population is confined to a 10,000-acre "impact area" which has been subjected to frequent wildfires from incendiary ammunition during the past 50 years. The great majority of the population occurs in subacid, clay loam or sandy clay loam soils over granite, although a small portion occurs on a 50-acre sill of basic rock with circumneutral soils. Subpopulations occupy all topographic positions except bottomlands, often (but not always) preferring slopes and ridge crests with shallow or rocky soils. Habitats, which typically burn at one- to five-year intervals, are predominantly thinly canopied oak-hickory woodlands, grassy oak-hickory "savannas," and openings in hardwood coppice. Within these habitats, the species also colonizes previously disturbed areas, such as old clearings and military jeep trails. The most common and typical associates include Quercus spp., Carya spp., Liquidambar styraciflua, Cornus florida, Rhus glabra, R. copallinum, Schizachyrium scoparium, Desmodium spp., Lespedeza spp., and various composites. A list of associated "indicators" might include Sorghastrum elliottii, Brickellia eupatorioides, Eupatorium godfreyanum, E. sessilifolium, Silphium compositum, and Helianthus divaricatus. In the floristically distinctive basic rock area, "indicator" associates include Viburnum rafinesquianum, Scleria oligantha, Clematis ochroleuca, Sanicula smallii, Salvia urticifolia, Parthenium auriculatum, and Helianthus strumosus.

Additional surveys at Fort Pickett in 1994-1995 resulted in Rhus michauxii being found not only in the above described habitat but also in habitats associated with disturbances from old homesites, fencerows, and agricultural fields (Van Alstine and Smith 1995). The habitat of the first known occurrence in Virginia found outside of Fort Pickett is described as ruderal next to a railroad grade with aggressive Lonicera japonica and other species including Pinus taeda, Liquidambar styraciflua, Juniperus virginiana, Campsis radicans, Lespedeza cuneata, Solidago altissima, Toxicodendron radicans, Rhus copallinum, etc.

Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Management efforts should focus on maintaining open habitat and increasing the number of sexually reproductive individuals (Center for Plant Conservation 2002). Rhus michauxii is shade intolerant, thus some form of disturbance, such as prescribed burning or mowing, is necessary to control the growth of other woody plants in its habitat (USFWS 1990). Hand-thinning of shading trees in the vicinity, if done carefully, may be beneficial (Patrick et al. 1995). Timber harvesting and roadside management should be done very carefully to protect this species' habitat (USFWS 1990). Of great concern is Rhus michauxii's low reproductive capacity due to the small number of populations containing both male and female plants (USFWS 1990). Reintroducing male or female plants into single sex populations should continue. Additional genetic resesearch to determine the success of efforts to conserve genetic diversity should also be conducted over time (Center for Plant Conservation 2002).
Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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Excellent Viability: An A-ranked occurrence of Rhus michauxii should have more than 250 stems or more than 100 stems if both sexes are present. The population should occur in open woods in excellent condition kept open by periodic fire or edaphic conditions.
Good Viability: A B-ranked occurrence of Rhus michauxii should have between 100 and 250 stems or between 25 and 100 stems if both sexes are present. The population should occur in a good quality open woods kept open by periodic fire, mechanical clearing, or edaphic conditions.
Fair Viability: A C-ranked occurrence of Rhus michauxii should have between 25 and 100 stems or fewer than 25 stems if both sexes are present. The population should occur in fair quality open to partially closed woods kept open by fire, mechanical clearing or edaphic conditions. The condition of the woods should be readily restorable with appropriate management.
Poor Viability: A D-ranked occurrence of Rhus michauxii should have fewer than 25 stems. The population may occur on a roadside or powerline right-of-way and be impacted by overgrowth of adjacent invasive vegetation not readily restorable with approprate management.
Justification: These specifications are based on current populations and expert opinion. Rhus michauxii is a dioecious shrub: fewer stems but evidence of both sexes indicates a diversity of genets which appears to be important in maintaining the population.
Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
Date: 23Dec2004
Author: Amoroso
Notes: based on SFO 1993 rank specifications
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 17Dec1993
NatureServe Conservation Status Factors Author: A. Tomaino (2004), rev. S. Mason, N. Van Alstine, and J. M. Moffett (2006)
Management Information Edition Date: 01Jul2004
Management Information Edition Author: Tomaino, A.
Element Ecology & Life History Edition Date: 02Jul2004

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Center for Plant Conservation. 2002. National Collection Plant Profile: Rhus michauxii. Online. Available: http://ridgwaydb.mobot.org/cpcweb/CPC_ViewProfile.asp?CPCNum=3743 (accessed 1 July 2004).

  • Hardin, J., and L. Phillips. 1985. Hybridization in eastern North American Rhus (Anacardiaceae). Association of Southeastern Biologists Bulletin 32(3): 99-108.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Murdock, N.A., and J. Moore. 1993. Recovery plan for Michaux's sumac (Rhus michauxii) Sargent. Prepared for the U.S. Fish and Wildlife Service, Southeast Region, Atlanta, GA.

  • Patrick, T.S., J.R. Allison, and G.A. Krakow. 1995. Protected plants of Georgia: an information manual on plants designated by the State of Georgia as endangered, threatened, rare, or unusual. Georgia Dept. Natural Resources, Wildlife Resources Division, Georgia Natural Heritage Program, Social Circle, Georgia. 218 pp + appendices.

  • Radford, A.E., H.E. Ahles, and C.R. Bell. 1968. Manual of the vascular flora of the Carolinas. Univ. North Carolina Press, Chapel Hill, NC. 1183 pp.

  • The Nature Conservancy. 1993. Rare and endangered plant survey and natural area inventory of Fort Bragg and Camp MacKall military reservations, North Carolina. Final report by The Nature Conservancy, Sandhills Field Office, December 1993.

  • U.S. Fish and Wildlife Service. 1989. Determination of endangered status for Rhus michauxii (Michaux's sumac). Federal Register 54(187): 39853-39857.

  • U.S. Fish and Wildlife Service. 1989. Proposed endangered status for Rhus michauxii (Michaux's sumac). Federal Register 54(4): 441-445.

  • U.S. Fish and Wildlife Service. 1990. August last update. Michaux's sumac (Rhus michauxii) Species Account. Endangered and threatened species of the southeastern United States (The Red Book), FWS Region 4. Online. Available: http://endangered.fws.gov/i/q/saq5t.html (accessed 1 July 2004).

  • Weakley, A. S. 2004. Flora of the Carolinas, Virginia, and Georgia. Draft as of March 2004. UNC Herbarium, North Carolina Botanical Garden, Chapel Hill. Available online: http://www.herbarium.unc.edu/flora.htm. Accessed 2004.

  • Weakley, A. S., compiler. 1993. Natural Heritage Program list of the rare plant species of North Carolina. North Carolina Department of Environment, Health, and Natural Resources, Division of Parks and Recreation, Natural Heritage Program. Raleigh. 79 pp.

  • Weakley, A.S. 1993. North Carolina Natural Heritage Program list of the rare plant species of North Carolina. Draft North Carolina Natural Heritage Program list of the watch list plant species. Natural Heritage Program, North Carolina Dept. Environment, Health and Natural Resources, Raleigh.

  • Weakley, A.S. 1996. Flora of the Carolinas and Virginia: working draft of 23 May 1996. The Nature Conservancy, Southeast Regional Office, Southern Conservation Science Dept., Chapel Hill, North Carolina. Unpaginated.

  • Wunderlin, R.P. and B.F. Hansen. 2003. Guide to the Vascular Plants of Florida. 2nd edition. University Press of Florida, Tampa. 788 pp.

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