Common Greenbrier

Normally, the peduncle of Smilax rotundifolia is about the same length as the petiole of the subtending leaf. In exceptional cases, the peduncle may be considerably longer, thereby making this widely distributed species difficult to distinguish from S. bona-nox and S. tamnoides. It lacks the marginal cartilaginous band found on the leaves of the former species and the hispid prickles of the stem of the latter. Specimens of S. tamnoides lacking prickles may be distinguished by their more strongly ridged stems.

Vines; rhizomes linear. Stems perennial, climbing, branching, terete to quadrangular, 5–6+ m × 6 mm, woody, glabrous; prickles green with dark tips, stout, to 12 mm. Leaves deciduous to evergreen, ± evenly disposed; petiole 0.5–1.5 cm; tendrils numerous; blade variable, bright green, drying to pale to brownish green, usually ovate to broadly ovate, with 3 (or 5) ± prominent veins, 4–17 × 4–16 cm, lustrous, not glaucous, glabrous abaxially, base cordate to rounded with acute insertion at petiole, margins entire, apex abruptly pointed. Umbels numerous, axillary to leaves, 5–12(–20)-flowered, open to dense, hemispherical to spherical; peduncle to 1.5 cm, longer or shorter than petiole of subtending leaf. Flowers: perianth pale yellowish green to bronze; tepals 3–4 mm; anthers shorter than to ± equaling filaments; ovule 1 per locule; pedicel 0.2–1.5 cm. Berries blue-black to black, globose, 5–8 mm, glaucous. 2n = 32.

N.S., Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Kans., Ky., La., Maine, Md., Mass., Mich., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Va., W.Va.

Flowering Apr--Jun.

Dry to moist, sometimes riparian woods, borders, hedgerows, thickets; 0--200m.

Smilax caduca Linnaeus; S. quadrangularis Muhlenberg ex Willdenow; S. rotundifolia var. crenulata Small & A. Heller; S. rotundifolia var. quadrangularis (Muhlenberg ex Willdenow) Alph. Wood

More info for the terms: chamaephyte, cover, fern, fire management, fire regime, fire use, forest, frequency, fruit, fuel, hardwood, headfire, heath, high-severity fire, ladder fuels, liana, litter, low-severity fire, mesic, natural, phanerophyte, prescribed fire, secondary colonizer, seed, shrubs, swamp, vine, vines, xeric

roundleaf greenbrier
common greenbrier


TAXONOMY:
The scientific name of roundleaf greenbrier is Smilax rotundifolia L. (Smilacaceae) [13,31].


LIFE FORM:
Vine

FEDERAL LEGAL STATUS:
None

OTHER STATUS:
Roundleaf greenbrier is listed as rare in Canada [1]. It is the only
woody monocot in southern Canada [22].





DISTRIBUTION AND OCCURRENCE
SPECIES: Smilax rotundifolia
GENERAL DISTRIBUTION:
Roundleaf greenbrier occurs throughout the eastern United States.  Its
range extends as far north as southern Nova Scotia and southern Ontario
and continues west to southern Michigan, Indiana, and southern Illinois;
south through southeastern Missouri to eastern Texas; and east to
northern Florida [13,14,31,34].







Distribution of roundleaf greenbrier. Map courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [2018, April 9] [48].





ECOSYSTEMS:
   FRES10  White - red - jack pine
   FRES11  Spruce - fir
   FRES12  Longleaf - slash pine
   FRES13  Loblolly - shortleaf pine
   FRES14  Oak - pine
   FRES15  Oak - hickory
   FRES16  Oak - gum - cypress
   FRES17  Elm - ash - cottonwood
   FRES18  Maple - beech - birch


STATES:
     AL  AR  CT  DE  FL  GA  IL  IN  KY  LA
     ME  MD  MA  MI  MS  MO  NH  NJ  NY  NC
     OH  OK  PA  RI  SC  TN  TX  VT  VA  WV
     NS  ON



BLM PHYSIOGRAPHIC REGIONS:
NO-ENTRY


KUCHLER PLANT ASSOCIATIONS:
   K089  Black Belt
   K095  Great Lakes pine forest
   K097  Southeastern spruce-fir forest
   K098  Northern floodplain forest
   K100  Oak - hickory forest
   K103  Mixed mesophytic forest
   K104  Appalachian oak forest
   K106  Northern hardwoods
   K110  Northeastern oak - pine forest
   K111  Oak - hickory - pine forest
   K112  Southern mixed forest
   K113  Southern floodplain forest


SAF COVER TYPES:
    20  White pine - northern red oak - red maple
    21  Eastern white pine
    23  Eastern hemlock
    30  Red spruce - yellow birch
    32  Red spruce
    44  Chestnut oak
    45  Pitch pine
    46  Eastern redcedar
    53  White oak
    70  Longleaf pine
    79  Virginia pine
    81  Loblolly pine
    82  Loblolly pine - hardwood
    83  Longleaf pine - slash pine
    95  Black willow
    97  Atlantic white-cedar
    98  Pond pine
   108  Red maple
   110  Black oak


HABITAT TYPES AND PLANT COMMUNITIES:
Roundleaf greenbrier occurs in a wide variety of plant communities.
Understory associates of roundleaf greenbrier in moist woods include
mapleleaf viburnum (Viburnum acerifolium), grape (Vitis spp.), flowering
dogwood (Cornus florida), New York fern (Thelypteris noveboracensis),
cat greenbrier (Smilax glauca), cane (Arundinaria gigantea), eastern
poison-ivy (Toxicodendron radicans), and Virginia creeper
(Parthenocissus quinquefolia). [2,12,18,17].

In Atlantic white-cedar (Chamaecyparis thyoides) communities in North
Carolina, roundleaf greenbrier occurs with sweetbay (Magnolia virginiana),
redbay (Persea borbonia), large gallberry (Ilex coriacea), hurrahbush
(Lyonia lucida), blueberry (Vaccinium spp.), and cinnamon fern (Osmunda
cinnamomea) [25].

In drier woods, heath balds, heath-shrub communities, and rhododendron
(Rhododendron spp.) thickets, roundleaf greenbrier occurs with black
huckleberry (Gaylussacia baccata), hillside blueberry (Vaccinium
pallidum), and low sweet blueberry (V. angustifolia).  Other associates
of dry sites include mountain-laurel (Kalmia latifolia), swamp
dog-laurel (Leucothoe axillaris), Carolina holly (Ilex ambigua), and
mountain white-alder (Clethra acuminata) [6,42,44].

Roundleaf greenbrier occurs in old fields with black locust (Robinia
pseudoacacia), sassafras (Sassafras albidum), blackberry (Rubus spp.),
blueberry, and bracken fern (Pteridium aquilinum) [12].


MANAGEMENT CONSIDERATIONS
SPECIES: Smilax rotundifolia
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Numerous birds and animals eat roundleaf greenbrier fruits.  The persistent
fruits are an important late winter and early spring food for wintering
birds including northern cardinals and white-throated sparrows [2].
White-tailed deer and lagomorphs browse the foliage [4,12,15,16].

Roundleaf greenbrier forms impenetrable thickets of prickly branches which
probably create good cover for small mammals and birds.


PALATABILITY:
The green canes, tender shoots, and leaves are palatable to white-tailed
deer [15,16].


NUTRITIONAL VALUE:
Ehrenfeld [9] determined nitrogen concentrations of roundleaf greenbrier
leaves and new twigs from four wetland communities in the New Jersey
pine barrens.  Nitrogen concentrations were 1.28 percent dry weight in
the floodplain community, 1.52 in the pine lowlands, 1.89 in the wet
hardwoods, and 2.09 in the dry hardwoods.  Nitrogen concentrations of
roundleaf greenbrier stems on all sites averaged 0.61 percent dry weight
[9].


COVER VALUE:
NO-ENTRY


VALUE FOR REHABILITATION OF DISTURBED SITES:
NO-ENTRY


OTHER USES AND VALUES:
NO-ENTRY


OTHER MANAGEMENT CONSIDERATIONS:
Niering and Goodwin [29] recommend roundleaf greenbrier and other clonal
shrubs for right-of-way clearings where trees interfere with powerlines.
Dense roundleaf greenbrier, hillside blueberry, and black huckleberry
thickets resisted invasion of trees for at least 15 years in a
right-of-way from which trees were originally removed by herbicide
application.

In Shenandoah National Park, Virginia, roundleaf greenbrier was more
important close to trails than in inaccessible areas, suggesting that it
is resistant to disturbance [19].

Medium and heavy thinning of a Louisiana loblolly pine (Pinus taeda)
plantation increased greenbrier (Smilax spp.) productivity [4].

Greenbriers (Smilax spp.) are resistant to most herbicides [47].  Two
years after a late summer application of glyphosate, roundleaf greenbrier
foliage appeared normal and healthy [41].

Propagation and eradication techniques are described for roundleaf greenbrier [12].


BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Smilax rotundifolia
GENERAL BOTANICAL CHARACTERISTICS:
Roundleaf greenbrier is a native liana that uses tendrils to climb
10 to 20 feet (3-6 m).  The leathery leaves are deciduous, although
sometimes tardily so in the southeastern states.  The stems are usually
quadrangular and diffusely branched with flattened prickles up to 0.3
inches (0.8 cm) long.  The fruit is a berry [13,14,31,40].  Roundleaf
greenbrier has long, slender, nontuberous rhizomes near the soil surface
[14,15,24].  Roundleaf greenbrier canes live 2 to 4 years [15].


RAUNKIAER LIFE FORM:
Phanerophyte
Chamaephyte


REGENERATION PROCESSES:
Roundleaf greenbrier regenerates by rhizomes and seed.  Rhizomes persist
for years after the plant has been top-killed by fire or other
disturbance [15].

On mesic sites in Connecticut dominated by shrubs, roundleaf greenbrier
clones averaged 10 inches (25 cm) of radial expansion a year.  On xeric
sites where drought and browsing by lagomorphs restricted growth, roundleaf
greenbrier clones decreased an average of 2 inches (5 cm) a year [29].
On sites in Ontario, roundleaf greenbrier did not spread vegetatively [22].

Roundleaf greenbrier produces some fruit every year [30].  Seeds are
dispersed by animals and water [26].  Seeds often germinate when
disturbance increases the amount of light on the soil and brings buried
seeds to the surface [30].  Pogge and Bearce [30] tested roundleaf greenbrier
seeds for total and potential germination.  Exposure to light
substantially increased germination.  Seeds stored for 5 years at 36 to
45 degrees Fahrenheit (2-7 deg C) and about 2 percent moisture content
had high viability.


SITE CHARACTERISTICS:
Roundleaf greenbrier is generally a submesic species, but extends onto
subxeric and xeric sites [42].  It occurs on a wide variety of sites;
these include south slopes and ridgetops in the southern Appalachian
Mountains [6,42], low damp flatwoods on the lower Atlantic Coastal Plain
[14], the inland coastal plain of Nova Scotia [33], and banks of
freshwater swamps in Massachusetts [7].  Optimum soil pH is 5.0 to 6.0
[12].


SUCCESSIONAL STATUS:
Roundleaf greenbrier is a pioneering species as well as a component of
forest understories.  Although it grows in low light conditions, roundleaf
greenbrier is also capable of relatively high photosynthetic rates in
full sunlight [5].  Shading of 10 to 20 percent of full sunlight may be
optimal, but good fruit production occurred in 70 to 80 percent shade in
West Virginia [12].

Roundleaf greenbrier is often found on recently logged sites, roadsides,
and old fields [12,13,20].  Once vines such as roundleaf greenbrier become
established on disturbed sites, they may dominate the early successional
stages [26].

Hemond and others [20] use roundleaf greenbrier cover greater than 5
percent as an indicator of 40- to 50-year-old forests of old-field
origin in southern Connecticut.  Roundleaf greenbrier declined more than 50
percent over 20 years of observation in this forest [20].


SEASONAL DEVELOPMENT:
Roundleaf greenbrier flowers from April to May in the southeastern states
[21,31,43], from May to June in the northeastern states [12,13], and in
June in southern Canada [34,35].  Fruits ripen in the fall.  All annual
growth is completed in a short time in the spring [12].


FIRE ECOLOGY
SPECIES: Smilax rotundifolia
FIRE ECOLOGY OR ADAPTATIONS:
Roundleaf greenbrier resists fire by sprouting from rhizomes [15,27,28].
Canopy openings caused by fire may favor roundleaf greenbrier. 

FIRE REGIMES:
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page
under "Find FIRE REGIMES".

POSTFIRE REGENERATION STRATEGY:
   Secondary colonizer - off-site seed


FIRE EFFECTS
SPECIES: Smilax rotundifolia
IMMEDIATE FIRE EFFECT ON PLANT:
Roundleaf greenbrier is top-killed by fire [46].


PLANT RESPONSE TO FIRE:
Roundleaf greenbrier sprouts from rhizomes after fire.  Roundleaf greenbrier
responded with vigorous vegetative reproduction to spring and fall
prescribed fires in eastern white pine (Pinus strobus) and eastern white
pine-hardwood forests in New Hampshire.  The fires were of low intensity,
with flames greater than 20 inches (50 cm) high, and burned only the
surface litter layer [46].

Roundleaf greenbrier sprouted after an early March headfire in a young
eastern Texas loblolly pine-shortleaf pine (P. echinata)-hardwood
forest.  The fire consumed 80 to 90 percent of the previous year's
needle and leaf fall and about 50 percent of the older accumulated
litter.  The average roundleaf greenbrier height 2 years after the fire was
46 inches (118 cm) with an average of 1.60 stems per plant.  Average
height on the unburned control was 187 inches (476 cm) with an average
of 1.73 stems per plant [37].

Annual and biennial early April fires were conducted in little bluestem
(Schizachyrium scoparium) grasslands in Connecticut [27,28].  The study
sites were on agricultural lands abandoned 40 to 60 years previously and
had up to 40 percent woody cover of clonal shrubs.  After 15 years of
burning, roundleaf greenbrier frequency increased over prefire levels on
one plot but decreased slightly on another due to heavy lagomorph use of
succulent postfire shoots.  Cover of roundleaf greenbrier changed very
little during the 18-year study, so the authors classified roundleaf
greenbrier as a persistent species rather than an increaser.  On unburned
plots adjacent to the burns, roundleaf greenbrier increased in cover and
frequency over the duration of the study.



DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

The Research Project Summary Early postfire response of southern
Appalachian
Table Mountain-pitch pine stands to prescribed fires in North Carolina and
Virginia
provides information on prescribed
fire use and postfire response

of plant community species, including roundleaf greenbrier, that was not

available when this species review was originally written.


FIRE MANAGEMENT CONSIDERATIONS:
Roundleaf greenbrier foliage was sampled 1 and 2 years after low-severity
and high-severity fires and compared to roundleaf greenbrier foliage in
unburned areas.  The first growing season after the low-severity fire,
roundleaf greenbrier protein content was 7.8 percent higher than on
unburned areas, but no difference was detected the second postfire
growing season.  One and two years after the high-severity fire, the
protein contents were 6 percent and 19 percent higher, respectively,
than foliage from unburned areas.  Neither fire produced substantial
changes in total solids, ash, ether content, crude fiber, or
nitrogen-free extract [8].

Greenbrier spp. (Smilax rotundifolia and S. laurifolia) are a component
of several fuel models for the coastal plain of North Carolina.  They
contribute to ladder fuels in the high pocosin type.  Greenbrier
intertwines with grass species in some types, impeding foot travel [45].



REFERENCES
SPECIES: Smilax rotundifolia




 1.  White, D. J.; Maher, R. V.; Argus, G. W. 1982. Smilax rotundifolia L.
In: Argus, George W.; White, David J., eds. Atlas of the rare vascular
plants of Ontario. Part 1. Ottawa, ON: National Museums of Canada,
National Museum of Natural Sciences. 1 p.  [23478]

Roundleaf greenbrier is listed as rare in Canada [1]. It is the only woody monocot in southern Canada [22].

Roundleaf greenbrier occurs throughout the eastern United States.  Its range extends as far north as southern Nova Scotia and southern Ontario and continues west to southern Michigan, Indiana, and southern Illinois; south through southeastern Missouri to eastern Texas; and east to northern Florida [13,14,31,34]. Distribution of roundleaf greenbrier. Map courtesy of USDA, NRCS. 2018. The PLANTS Database. National Plant Data Team, Greensboro, NC [2018, April 9] [48].

More info for the terms: fuel, high-severity fire, ladder fuels, low-severity fire

Roundleaf greenbrier foliage was sampled 1 and 2 years after low-severity and high-severity fires and compared to roundleaf greenbrier foliage in unburned areas.  The first growing season after the low-severity fire, roundleaf greenbrier protein content was 7.8 percent higher than on unburned areas, but no difference was detected the second postfire growing season.  One and two years after the high-severity fire, the protein contents were 6 percent and 19 percent higher, respectively, than foliage from unburned areas.  Neither fire produced substantial changes in total solids, ash, ether content, crude fiber, or nitrogen-free extract [8]. Greenbrier spp. (Smilax rotundifolia and S. laurifolia) are a component of several fuel models for the coastal plain of North Carolina.  They contribute to ladder fuels in the high pocosin type.  Greenbrier intertwines with grass species in some types, impeding foot travel [45].

More info for the terms: fern, heath, swamp

Roundleaf greenbrier occurs in a wide variety of plant communities.
Understory associates of roundleaf greenbrier in moist woods include
mapleleaf viburnum (Viburnum acerifolium), grape (Vitis spp.), flowering
dogwood (Cornus florida), New York fern (Thelypteris noveboracensis),
cat greenbrier (Smilax glauca), cane (Arundinaria gigantea), eastern
poison-ivy (Toxicodendron radicans), and Virginia creeper
(Parthenocissus quinquefolia). [2,12,18,17].

In Atlantic white-cedar (Chamaecyparis thyoides) communities in North
Carolina, roundleaf greenbrier occurs with sweetbay (Magnolia virginiana),
redbay (Persea borbonia), large gallberry (Ilex coriacea), hurrahbush
(Lyonia lucida), blueberry (Vaccinium spp.), and cinnamon fern (Osmunda
cinnamomea) [25].

In drier woods, heath balds, heath-shrub communities, and rhododendron
(Rhododendron spp.) thickets, roundleaf greenbrier occurs with black
huckleberry (Gaylussacia baccata), hillside blueberry (Vaccinium
pallidum), and low sweet blueberry (V. angustifolia).  Other associates
of dry sites include mountain-laurel (Kalmia latifolia), swamp
dog-laurel (Leucothoe axillaris), Carolina holly (Ilex ambigua), and
mountain white-alder (Clethra acuminata) [6,42,44].

Roundleaf greenbrier occurs in old fields with black locust (Robinia
pseudoacacia), sassafras (Sassafras albidum), blackberry (Rubus spp.),
blueberry, and bracken fern (Pteridium aquilinum) [12].

More info for the term: vine

Vine

More info for the term: shrubs

Niering and Goodwin [29] recommend roundleaf greenbrier and other clonal
shrubs for right-of-way clearings where trees interfere with powerlines.
Dense roundleaf greenbrier, hillside blueberry, and black huckleberry
thickets resisted invasion of trees for at least 15 years in a
right-of-way from which trees were originally removed by herbicide
application.

In Shenandoah National Park, Virginia, roundleaf greenbrier was more
important close to trails than in inaccessible areas, suggesting that it
is resistant to disturbance [19].

Medium and heavy thinning of a Louisiana loblolly pine (Pinus taeda)
plantation increased greenbrier (Smilax spp.) productivity [4].

Greenbriers (Smilax spp.) are resistant to most herbicides [47].  Two
years after a late summer application of glyphosate, roundleaf greenbrier
foliage appeared normal and healthy [41].

Propagation and eradication techniques are described for roundleaf greenbrier [12].

More info on this topic.

Roundleaf greenbrier flowers from April to May in the southeastern states [21,31,43], from May to June in the northeastern states [12,13], and in June in southern Canada [34,35].  Fruits ripen in the fall.  All annual growth is completed in a short time in the spring [12].

More info for the term: secondary colonizer

   Secondary colonizer - off-site seed

More info for the terms: chamaephyte, cover, fern, fire management, fire regime, fire use, forest, frequency, fruit, fuel, hardwood, headfire, heath, high-severity fire, ladder fuels, liana, litter, low-severity fire, mesic, natural, phanerophyte, prescribed fire, secondary colonizer, seed, shrubs, swamp, vine, vines, xeric

Smilax rotundifolia L. var. crenulata Small & A. Heller
Smilax rotundifolia L. var. quadrangularis (Muhl. ex Willd.) Alph. Wood [34,40,43]


NRCS PLANT CODE [48]:
SMRO


COMMON NAMES:
roundleaf greenbrier
common greenbrier


TAXONOMY:
The scientific name of roundleaf greenbrier is Smilax rotundifolia L. (Smilacaceae) [13,31].


LIFE FORM:
Vine

FEDERAL LEGAL STATUS:
None

OTHER STATUS:
Roundleaf greenbrier is listed as rare in Canada [1]. It is the only
woody monocot in southern Canada [22].





DISTRIBUTION AND OCCURRENCE
SPECIES: Smilax rotundifolia
GENERAL DISTRIBUTION:
Roundleaf greenbrier occurs throughout the eastern United States.  Its
range extends as far north as southern Nova Scotia and southern Ontario
and continues west to southern Michigan, Indiana, and southern Illinois;
south through southeastern Missouri to eastern Texas; and east to
northern Florida [13,14,31,34].







Distribution of roundleaf greenbrier. Map courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [2018, April 9] [48].





ECOSYSTEMS:
   FRES10  White - red - jack pine
   FRES11  Spruce - fir
   FRES12  Longleaf - slash pine
   FRES13  Loblolly - shortleaf pine
   FRES14  Oak - pine
   FRES15  Oak - hickory
   FRES16  Oak - gum - cypress
   FRES17  Elm - ash - cottonwood
   FRES18  Maple - beech - birch


STATES:
     AL  AR  CT  DE  FL  GA  IL  IN  KY  LA
     ME  MD  MA  MI  MS  MO  NH  NJ  NY  NC
     OH  OK  PA  RI  SC  TN  TX  VT  VA  WV
     NS  ON



BLM PHYSIOGRAPHIC REGIONS:
NO-ENTRY


KUCHLER PLANT ASSOCIATIONS:
   K089  Black Belt
   K095  Great Lakes pine forest
   K097  Southeastern spruce-fir forest
   K098  Northern floodplain forest
   K100  Oak - hickory forest
   K103  Mixed mesophytic forest
   K104  Appalachian oak forest
   K106  Northern hardwoods
   K110  Northeastern oak - pine forest
   K111  Oak - hickory - pine forest
   K112  Southern mixed forest
   K113  Southern floodplain forest


SAF COVER TYPES:
    20  White pine - northern red oak - red maple
    21  Eastern white pine
    23  Eastern hemlock
    30  Red spruce - yellow birch
    32  Red spruce
    44  Chestnut oak
    45  Pitch pine
    46  Eastern redcedar
    53  White oak
    70  Longleaf pine
    79  Virginia pine
    81  Loblolly pine
    82  Loblolly pine - hardwood
    83  Longleaf pine - slash pine
    95  Black willow
    97  Atlantic white-cedar
    98  Pond pine
   108  Red maple
   110  Black oak


HABITAT TYPES AND PLANT COMMUNITIES:
Roundleaf greenbrier occurs in a wide variety of plant communities.
Understory associates of roundleaf greenbrier in moist woods include
mapleleaf viburnum (Viburnum acerifolium), grape (Vitis spp.), flowering
dogwood (Cornus florida), New York fern (Thelypteris noveboracensis),
cat greenbrier (Smilax glauca), cane (Arundinaria gigantea), eastern
poison-ivy (Toxicodendron radicans), and Virginia creeper
(Parthenocissus quinquefolia). [2,12,18,17].

In Atlantic white-cedar (Chamaecyparis thyoides) communities in North
Carolina, roundleaf greenbrier occurs with sweetbay (Magnolia virginiana),
redbay (Persea borbonia), large gallberry (Ilex coriacea), hurrahbush
(Lyonia lucida), blueberry (Vaccinium spp.), and cinnamon fern (Osmunda
cinnamomea) [25].

In drier woods, heath balds, heath-shrub communities, and rhododendron
(Rhododendron spp.) thickets, roundleaf greenbrier occurs with black
huckleberry (Gaylussacia baccata), hillside blueberry (Vaccinium
pallidum), and low sweet blueberry (V. angustifolia).  Other associates
of dry sites include mountain-laurel (Kalmia latifolia), swamp
dog-laurel (Leucothoe axillaris), Carolina holly (Ilex ambigua), and
mountain white-alder (Clethra acuminata) [6,42,44].

Roundleaf greenbrier occurs in old fields with black locust (Robinia
pseudoacacia), sassafras (Sassafras albidum), blackberry (Rubus spp.),
blueberry, and bracken fern (Pteridium aquilinum) [12].


MANAGEMENT CONSIDERATIONS
SPECIES: Smilax rotundifolia
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Numerous birds and animals eat roundleaf greenbrier fruits.  The persistent
fruits are an important late winter and early spring food for wintering
birds including northern cardinals and white-throated sparrows [2].
White-tailed deer and lagomorphs browse the foliage [4,12,15,16].

Roundleaf greenbrier forms impenetrable thickets of prickly branches which
probably create good cover for small mammals and birds.


PALATABILITY:
The green canes, tender shoots, and leaves are palatable to white-tailed
deer [15,16].


NUTRITIONAL VALUE:
Ehrenfeld [9] determined nitrogen concentrations of roundleaf greenbrier
leaves and new twigs from four wetland communities in the New Jersey
pine barrens.  Nitrogen concentrations were 1.28 percent dry weight in
the floodplain community, 1.52 in the pine lowlands, 1.89 in the wet
hardwoods, and 2.09 in the dry hardwoods.  Nitrogen concentrations of
roundleaf greenbrier stems on all sites averaged 0.61 percent dry weight
[9].


COVER VALUE:
NO-ENTRY


VALUE FOR REHABILITATION OF DISTURBED SITES:
NO-ENTRY


OTHER USES AND VALUES:
NO-ENTRY


OTHER MANAGEMENT CONSIDERATIONS:
Niering and Goodwin [29] recommend roundleaf greenbrier and other clonal
shrubs for right-of-way clearings where trees interfere with powerlines.
Dense roundleaf greenbrier, hillside blueberry, and black huckleberry
thickets resisted invasion of trees for at least 15 years in a
right-of-way from which trees were originally removed by herbicide
application.

In Shenandoah National Park, Virginia, roundleaf greenbrier was more
important close to trails than in inaccessible areas, suggesting that it
is resistant to disturbance [19].

Medium and heavy thinning of a Louisiana loblolly pine (Pinus taeda)
plantation increased greenbrier (Smilax spp.) productivity [4].

Greenbriers (Smilax spp.) are resistant to most herbicides [47].  Two
years after a late summer application of glyphosate, roundleaf greenbrier
foliage appeared normal and healthy [41].

Propagation and eradication techniques are described for roundleaf greenbrier [12].


BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Smilax rotundifolia
GENERAL BOTANICAL CHARACTERISTICS:
Roundleaf greenbrier is a native liana that uses tendrils to climb
10 to 20 feet (3-6 m).  The leathery leaves are deciduous, although
sometimes tardily so in the southeastern states.  The stems are usually
quadrangular and diffusely branched with flattened prickles up to 0.3
inches (0.8 cm) long.  The fruit is a berry [13,14,31,40].  Roundleaf
greenbrier has long, slender, nontuberous rhizomes near the soil surface
[14,15,24].  Roundleaf greenbrier canes live 2 to 4 years [15].


RAUNKIAER LIFE FORM:
Phanerophyte
Chamaephyte


REGENERATION PROCESSES:
Roundleaf greenbrier regenerates by rhizomes and seed.  Rhizomes persist
for years after the plant has been top-killed by fire or other
disturbance [15].

On mesic sites in Connecticut dominated by shrubs, roundleaf greenbrier
clones averaged 10 inches (25 cm) of radial expansion a year.  On xeric
sites where drought and browsing by lagomorphs restricted growth, roundleaf
greenbrier clones decreased an average of 2 inches (5 cm) a year [29].
On sites in Ontario, roundleaf greenbrier did not spread vegetatively [22].

Roundleaf greenbrier produces some fruit every year [30].  Seeds are
dispersed by animals and water [26].  Seeds often germinate when
disturbance increases the amount of light on the soil and brings buried
seeds to the surface [30].  Pogge and Bearce [30] tested roundleaf greenbrier
seeds for total and potential germination.  Exposure to light
substantially increased germination.  Seeds stored for 5 years at 36 to
45 degrees Fahrenheit (2-7 deg C) and about 2 percent moisture content
had high viability.


SITE CHARACTERISTICS:
Roundleaf greenbrier is generally a submesic species, but extends onto
subxeric and xeric sites [42].  It occurs on a wide variety of sites;
these include south slopes and ridgetops in the southern Appalachian
Mountains [6,42], low damp flatwoods on the lower Atlantic Coastal Plain
[14], the inland coastal plain of Nova Scotia [33], and banks of
freshwater swamps in Massachusetts [7].  Optimum soil pH is 5.0 to 6.0
[12].


SUCCESSIONAL STATUS:
Roundleaf greenbrier is a pioneering species as well as a component of
forest understories.  Although it grows in low light conditions, roundleaf
greenbrier is also capable of relatively high photosynthetic rates in
full sunlight [5].  Shading of 10 to 20 percent of full sunlight may be
optimal, but good fruit production occurred in 70 to 80 percent shade in
West Virginia [12].

Roundleaf greenbrier is often found on recently logged sites, roadsides,
and old fields [12,13,20].  Once vines such as roundleaf greenbrier become
established on disturbed sites, they may dominate the early successional
stages [26].

Hemond and others [20] use roundleaf greenbrier cover greater than 5
percent as an indicator of 40- to 50-year-old forests of old-field
origin in southern Connecticut.  Roundleaf greenbrier declined more than 50
percent over 20 years of observation in this forest [20].


SEASONAL DEVELOPMENT:
Roundleaf greenbrier flowers from April to May in the southeastern states
[21,31,43], from May to June in the northeastern states [12,13], and in
June in southern Canada [34,35].  Fruits ripen in the fall.  All annual
growth is completed in a short time in the spring [12].


FIRE ECOLOGY
SPECIES: Smilax rotundifolia
FIRE ECOLOGY OR ADAPTATIONS:
Roundleaf greenbrier resists fire by sprouting from rhizomes [15,27,28].
Canopy openings caused by fire may favor roundleaf greenbrier. 

FIRE REGIMES:
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page
under "Find FIRE REGIMES".

POSTFIRE REGENERATION STRATEGY:
   Secondary colonizer - off-site seed


FIRE EFFECTS
SPECIES: Smilax rotundifolia
IMMEDIATE FIRE EFFECT ON PLANT:
Roundleaf greenbrier is top-killed by fire [46].


PLANT RESPONSE TO FIRE:
Roundleaf greenbrier sprouts from rhizomes after fire.  Roundleaf greenbrier
responded with vigorous vegetative reproduction to spring and fall
prescribed fires in eastern white pine (Pinus strobus) and eastern white
pine-hardwood forests in New Hampshire.  The fires were of low intensity,
with flames greater than 20 inches (50 cm) high, and burned only the
surface litter layer [46].

Roundleaf greenbrier sprouted after an early March headfire in a young
eastern Texas loblolly pine-shortleaf pine (P. echinata)-hardwood
forest.  The fire consumed 80 to 90 percent of the previous year's
needle and leaf fall and about 50 percent of the older accumulated
litter.  The average roundleaf greenbrier height 2 years after the fire was
46 inches (118 cm) with an average of 1.60 stems per plant.  Average
height on the unburned control was 187 inches (476 cm) with an average
of 1.73 stems per plant [37].

Annual and biennial early April fires were conducted in little bluestem
(Schizachyrium scoparium) grasslands in Connecticut [27,28].  The study
sites were on agricultural lands abandoned 40 to 60 years previously and
had up to 40 percent woody cover of clonal shrubs.  After 15 years of
burning, roundleaf greenbrier frequency increased over prefire levels on
one plot but decreased slightly on another due to heavy lagomorph use of
succulent postfire shoots.  Cover of roundleaf greenbrier changed very
little during the 18-year study, so the authors classified roundleaf
greenbrier as a persistent species rather than an increaser.  On unburned
plots adjacent to the burns, roundleaf greenbrier increased in cover and
frequency over the duration of the study.



DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

The Research Project Summary Early postfire response of southern
Appalachian
Table Mountain-pitch pine stands to prescribed fires in North Carolina and
Virginia
provides information on prescribed
fire use and postfire response

of plant community species, including roundleaf greenbrier, that was not

available when this species review was originally written.


FIRE MANAGEMENT CONSIDERATIONS:
Roundleaf greenbrier foliage was sampled 1 and 2 years after low-severity
and high-severity fires and compared to roundleaf greenbrier foliage in
unburned areas.  The first growing season after the low-severity fire,
roundleaf greenbrier protein content was 7.8 percent higher than on
unburned areas, but no difference was detected the second postfire
growing season.  One and two years after the high-severity fire, the
protein contents were 6 percent and 19 percent higher, respectively,
than foliage from unburned areas.  Neither fire produced substantial
changes in total solids, ash, ether content, crude fiber, or
nitrogen-free extract [8].

Greenbrier spp. (Smilax rotundifolia and S. laurifolia) are a component
of several fuel models for the coastal plain of North Carolina.  They
contribute to ladder fuels in the high pocosin type.  Greenbrier
intertwines with grass species in some types, impeding foot travel [45].



REFERENCES
SPECIES: Smilax rotundifolia




 1.  White, D. J.; Maher, R. V.; Argus, G. W. 1982. Smilax rotundifolia L.
In: Argus, George W.; White, David J., eds. Atlas of the rare vascular
plants of Ontario. Part 1. Ottawa, ON: National Museums of Canada,
National Museum of Natural Sciences. 1 p.  [23478]

More info for the terms: chamaephyte, cover, fern, fire management, fire regime, fire use, forest, frequency, fruit, fuel, hardwood, headfire, heath, high-severity fire, ladder fuels, liana, litter, low-severity fire, mesic, natural, phanerophyte, prescribed fire, secondary colonizer, seed, shrubs, swamp, vine, vines, xeric

The scientific name of roundleaf greenbrier is Smilax rotundifolia L. (Smilacaceae) [13,31].

LIFE FORM:
Vine

FEDERAL LEGAL STATUS:
None

OTHER STATUS:
Roundleaf greenbrier is listed as rare in Canada [1]. It is the only
woody monocot in southern Canada [22].


DISTRIBUTION AND OCCURRENCE
SPECIES: Smilax rotundifolia
GENERAL DISTRIBUTION:
Roundleaf greenbrier occurs throughout the eastern United States.  Its
range extends as far north as southern Nova Scotia and southern Ontario
and continues west to southern Michigan, Indiana, and southern Illinois;
south through southeastern Missouri to eastern Texas; and east to
northern Florida [13,14,31,34].

Distribution of roundleaf greenbrier. Map courtesy of USDA, NRCS. 2018. The PLANTS Database.
National Plant Data Team, Greensboro, NC [2018, April 9] [48].



ECOSYSTEMS:
   FRES10  White - red - jack pine
   FRES11  Spruce - fir
   FRES12  Longleaf - slash pine
   FRES13  Loblolly - shortleaf pine
   FRES14  Oak - pine
   FRES15  Oak - hickory
   FRES16  Oak - gum - cypress
   FRES17  Elm - ash - cottonwood
   FRES18  Maple - beech - birch

STATES:
     AL  AR  CT  DE  FL  GA  IL  IN  KY  LA
     ME  MD  MA  MI  MS  MO  NH  NJ  NY  NC
     OH  OK  PA  RI  SC  TN  TX  VT  VA  WV
     NS  ON

BLM PHYSIOGRAPHIC REGIONS:
NO-ENTRY

KUCHLER PLANT ASSOCIATIONS:
   K089  Black Belt
   K095  Great Lakes pine forest
   K097  Southeastern spruce-fir forest
   K098  Northern floodplain forest
   K100  Oak - hickory forest
   K103  Mixed mesophytic forest
   K104  Appalachian oak forest
   K106  Northern hardwoods
   K110  Northeastern oak - pine forest
   K111  Oak - hickory - pine forest
   K112  Southern mixed forest
   K113  Southern floodplain forest

SAF COVER TYPES:
    20  White pine - northern red oak - red maple
    21  Eastern white pine
    23  Eastern hemlock
    30  Red spruce - yellow birch
    32  Red spruce
    44  Chestnut oak
    45  Pitch pine
    46  Eastern redcedar
    53  White oak
    70  Longleaf pine
    79  Virginia pine
    81  Loblolly pine
    82  Loblolly pine - hardwood
    83  Longleaf pine - slash pine
    95  Black willow
    97  Atlantic white-cedar
    98  Pond pine
   108  Red maple
   110  Black oak

HABITAT TYPES AND PLANT COMMUNITIES:
Roundleaf greenbrier occurs in a wide variety of plant communities.
Understory associates of roundleaf greenbrier in moist woods include
mapleleaf viburnum (Viburnum acerifolium), grape (Vitis spp.), flowering
dogwood (Cornus florida), New York fern (Thelypteris noveboracensis),
cat greenbrier (Smilax glauca), cane (Arundinaria gigantea), eastern
poison-ivy (Toxicodendron radicans), and Virginia creeper
(Parthenocissus quinquefolia). [2,12,18,17].

In Atlantic white-cedar (Chamaecyparis thyoides) communities in North
Carolina, roundleaf greenbrier occurs with sweetbay (Magnolia virginiana),
redbay (Persea borbonia), large gallberry (Ilex coriacea), hurrahbush
(Lyonia lucida), blueberry (Vaccinium spp.), and cinnamon fern (Osmunda
cinnamomea) [25].

In drier woods, heath balds, heath-shrub communities, and rhododendron
(Rhododendron spp.) thickets, roundleaf greenbrier occurs with black
huckleberry (Gaylussacia baccata), hillside blueberry (Vaccinium
pallidum), and low sweet blueberry (V. angustifolia).  Other associates
of dry sites include mountain-laurel (Kalmia latifolia), swamp
dog-laurel (Leucothoe axillaris), Carolina holly (Ilex ambigua), and
mountain white-alder (Clethra acuminata) [6,42,44].

Roundleaf greenbrier occurs in old fields with black locust (Robinia
pseudoacacia), sassafras (Sassafras albidum), blackberry (Rubus spp.),
blueberry, and bracken fern (Pteridium aquilinum) [12].


MANAGEMENT CONSIDERATIONS
SPECIES: Smilax rotundifolia
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Numerous birds and animals eat roundleaf greenbrier fruits.  The persistent
fruits are an important late winter and early spring food for wintering
birds including northern cardinals and white-throated sparrows [2].
White-tailed deer and lagomorphs browse the foliage [4,12,15,16].

Roundleaf greenbrier forms impenetrable thickets of prickly branches which
probably create good cover for small mammals and birds.

PALATABILITY:
The green canes, tender shoots, and leaves are palatable to white-tailed
deer [15,16].

NUTRITIONAL VALUE:
Ehrenfeld [9] determined nitrogen concentrations of roundleaf greenbrier
leaves and new twigs from four wetland communities in the New Jersey
pine barrens.  Nitrogen concentrations were 1.28 percent dry weight in
the floodplain community, 1.52 in the pine lowlands, 1.89 in the wet
hardwoods, and 2.09 in the dry hardwoods.  Nitrogen concentrations of
roundleaf greenbrier stems on all sites averaged 0.61 percent dry weight
[9].

COVER VALUE:
NO-ENTRY

VALUE FOR REHABILITATION OF DISTURBED SITES:
NO-ENTRY

OTHER USES AND VALUES:
NO-ENTRY

OTHER MANAGEMENT CONSIDERATIONS:
Niering and Goodwin [29] recommend roundleaf greenbrier and other clonal
shrubs for right-of-way clearings where trees interfere with powerlines.
Dense roundleaf greenbrier, hillside blueberry, and black huckleberry
thickets resisted invasion of trees for at least 15 years in a
right-of-way from which trees were originally removed by herbicide
application.

In Shenandoah National Park, Virginia, roundleaf greenbrier was more
important close to trails than in inaccessible areas, suggesting that it
is resistant to disturbance [19].

Medium and heavy thinning of a Louisiana loblolly pine (Pinus taeda)
plantation increased greenbrier (Smilax spp.) productivity [4].

Greenbriers (Smilax spp.) are resistant to most herbicides [47].  Two
years after a late summer application of glyphosate, roundleaf greenbrier
foliage appeared normal and healthy [41].

Propagation and eradication techniques are described for roundleaf greenbrier [12].


BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Smilax rotundifolia
GENERAL BOTANICAL CHARACTERISTICS:
Roundleaf greenbrier is a native liana that uses tendrils to climb
10 to 20 feet (3-6 m).  The leathery leaves are deciduous, although
sometimes tardily so in the southeastern states.  The stems are usually
quadrangular and diffusely branched with flattened prickles up to 0.3
inches (0.8 cm) long.  The fruit is a berry [13,14,31,40].  Roundleaf
greenbrier has long, slender, nontuberous rhizomes near the soil surface
[14,15,24].  Roundleaf greenbrier canes live 2 to 4 years [15].

RAUNKIAER LIFE FORM:
Phanerophyte
Chamaephyte

REGENERATION PROCESSES:
Roundleaf greenbrier regenerates by rhizomes and seed.  Rhizomes persist
for years after the plant has been top-killed by fire or other
disturbance [15].

On mesic sites in Connecticut dominated by shrubs, roundleaf greenbrier
clones averaged 10 inches (25 cm) of radial expansion a year.  On xeric
sites where drought and browsing by lagomorphs restricted growth, roundleaf
greenbrier clones decreased an average of 2 inches (5 cm) a year [29].
On sites in Ontario, roundleaf greenbrier did not spread vegetatively [22].

Roundleaf greenbrier produces some fruit every year [30].  Seeds are
dispersed by animals and water [26].  Seeds often germinate when
disturbance increases the amount of light on the soil and brings buried
seeds to the surface [30].  Pogge and Bearce [30] tested roundleaf greenbrier
seeds for total and potential germination.  Exposure to light
substantially increased germination.  Seeds stored for 5 years at 36 to
45 degrees Fahrenheit (2-7 deg C) and about 2 percent moisture content
had high viability.

SITE CHARACTERISTICS:
Roundleaf greenbrier is generally a submesic species, but extends onto
subxeric and xeric sites [42].  It occurs on a wide variety of sites;
these include south slopes and ridgetops in the southern Appalachian
Mountains [6,42], low damp flatwoods on the lower Atlantic Coastal Plain
[14], the inland coastal plain of Nova Scotia [33], and banks of
freshwater swamps in Massachusetts [7].  Optimum soil pH is 5.0 to 6.0
[12].

SUCCESSIONAL STATUS:
Roundleaf greenbrier is a pioneering species as well as a component of
forest understories.  Although it grows in low light conditions, roundleaf
greenbrier is also capable of relatively high photosynthetic rates in
full sunlight [5].  Shading of 10 to 20 percent of full sunlight may be
optimal, but good fruit production occurred in 70 to 80 percent shade in
West Virginia [12].

Roundleaf greenbrier is often found on recently logged sites, roadsides,
and old fields [12,13,20].  Once vines such as roundleaf greenbrier become
established on disturbed sites, they may dominate the early successional
stages [26].

Hemond and others [20] use roundleaf greenbrier cover greater than 5
percent as an indicator of 40- to 50-year-old forests of old-field
origin in southern Connecticut.  Roundleaf greenbrier declined more than 50
percent over 20 years of observation in this forest [20].

SEASONAL DEVELOPMENT:
Roundleaf greenbrier flowers from April to May in the southeastern states
[21,31,43], from May to June in the northeastern states [12,13], and in
June in southern Canada [34,35].  Fruits ripen in the fall.  All annual
growth is completed in a short time in the spring [12].


FIRE ECOLOGY
SPECIES: Smilax rotundifolia
FIRE ECOLOGY OR ADAPTATIONS:
Roundleaf greenbrier resists fire by sprouting from rhizomes [15,27,28].
Canopy openings caused by fire may favor roundleaf greenbrier. 

FIRE REGIMES:
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page
under "Find FIRE REGIMES".

POSTFIRE REGENERATION STRATEGY:
   Secondary colonizer - off-site seed


FIRE EFFECTS
SPECIES: Smilax rotundifolia
IMMEDIATE FIRE EFFECT ON PLANT:
Roundleaf greenbrier is top-killed by fire [46].


PLANT RESPONSE TO FIRE:
Roundleaf greenbrier sprouts from rhizomes after fire.  Roundleaf greenbrier
responded with vigorous vegetative reproduction to spring and fall
prescribed fires in eastern white pine (Pinus strobus) and eastern white
pine-hardwood forests in New Hampshire.  The fires were of low intensity,
with flames greater than 20 inches (50 cm) high, and burned only the
surface litter layer [46].

Roundleaf greenbrier sprouted after an early March headfire in a young
eastern Texas loblolly pine-shortleaf pine (P. echinata)-hardwood
forest.  The fire consumed 80 to 90 percent of the previous year's
needle and leaf fall and about 50 percent of the older accumulated
litter.  The average roundleaf greenbrier height 2 years after the fire was
46 inches (118 cm) with an average of 1.60 stems per plant.  Average
height on the unburned control was 187 inches (476 cm) with an average
of 1.73 stems per plant [37].

Annual and biennial early April fires were conducted in little bluestem
(Schizachyrium scoparium) grasslands in Connecticut [27,28].  The study
sites were on agricultural lands abandoned 40 to 60 years previously and
had up to 40 percent woody cover of clonal shrubs.  After 15 years of
burning, roundleaf greenbrier frequency increased over prefire levels on
one plot but decreased slightly on another due to heavy lagomorph use of
succulent postfire shoots.  Cover of roundleaf greenbrier changed very
little during the 18-year study, so the authors classified roundleaf
greenbrier as a persistent species rather than an increaser.  On unburned
plots adjacent to the burns, roundleaf greenbrier increased in cover and
frequency over the duration of the study.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

The Research Project Summary Early postfire response of southern
Appalachian
Table Mountain-pitch pine stands to prescribed fires in North Carolina and
Virginia
provides information on prescribed
fire use and postfire response

of plant community species, including roundleaf greenbrier, that was not

available when this species review was originally written.
FIRE MANAGEMENT CONSIDERATIONS:
Roundleaf greenbrier foliage was sampled 1 and 2 years after low-severity
and high-severity fires and compared to roundleaf greenbrier foliage in
unburned areas.  The first growing season after the low-severity fire,
roundleaf greenbrier protein content was 7.8 percent higher than on
unburned areas, but no difference was detected the second postfire
growing season.  One and two years after the high-severity fire, the
protein contents were 6 percent and 19 percent higher, respectively,
than foliage from unburned areas.  Neither fire produced substantial
changes in total solids, ash, ether content, crude fiber, or
nitrogen-free extract [8].

Greenbrier spp. (Smilax rotundifolia and S. laurifolia) are a component
of several fuel models for the coastal plain of North Carolina.  They
contribute to ladder fuels in the high pocosin type.  Greenbrier
intertwines with grass species in some types, impeding foot travel [45].



REFERENCES
SPECIES: Smilax rotundifolia

 1.  White, D. J.; Maher, R. V.; Argus, G. W. 1982. Smilax rotundifolia L.
In: Argus, George W.; White, David J., eds. Atlas of the rare vascular
plants of Ontario. Part 1. Ottawa, ON: National Museums of Canada,
National Museum of Natural Sciences. 1 p.  [23478]

Smilax rotundifolia, also known as roundleaf greenbrier or common greenbrier, is a woody vine native to the southeastern and eastern United States and eastern Canada. It is a common and conspicuous part of the natural forest ecosystems in much of its native range. The leaves are glossy green, petioled, alternate, and circular to heart-shaped. They are generally 5–13 cm long. Common greenbrier climbs other plants using green tendrils growing out of the petioles.

The stems are rounded and green and are armed with sharp thorns. The flowers are greenish white, and are produced from April to August. The fruit is a bluish black berry that ripens in September.