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Trillium pusillum

Michx.

Least Trillium

G4Apparently Secure Found in 2 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
Least concernIUCN
MediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.131904
Element CodePMLIL200Q0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
IUCNLeast concern
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderLiliales
FamilyMelanthiaceae
GenusTrillium
Other Common Names
dwarf wakerobin (EN) Dwarf Wakerobin (EN)
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.
Taxonomic Comments
A distinctive, widespread but rare trillium, and as treated here includes several varieties. An additional variety (var. monticulum = var. monticola) has been named, but is now generally considered to be within the range of variation of var. virginianum. The Trillium pusillum complex has presented taxonomic confusion in the past with varying numbers of varieties described by authors. There is, however, merging evidence from DNA sequence variability that indicates there are clear boundaries within T. pusillum that align with both morphological and habitat differences revealing several distinct species, some of which have been described as varieties in the past (Schilling et al. 2017). Some of these varieties will be elevated to species rank, and T. georgianum is the first in the series to be recognized (Schilling et al. 2017).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2021-01-27
Change Date2021-01-27
Edition Date2021-01-27
Edition AuthorsA. Weakley (1992), rev. L. Morse (1994), rev. L. Oliver (2020)
Threat ImpactMedium
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of OccurrencesUnknown
Rank Reasons
The taxonomy of Trillium pusillum has evolved to include at least four varities, however, future publications are likely describing additional taxa. Trillium pusillum as used here has four varieties: Trillium pusillum var. monticulum, Trillium pusillum var. ozarkanum, Trillium pusillum var. pusillum, and Trillium pusillum var. virginianum. All of the varieties are rare; see each one for more information. The former var. texanum is excluded and treated as a distinct species (Trillium texanum).
Range Extent Comments
Trillium pusillum occurs from Maryland, West Virginia, Virginia south to North Carolina, South Carolina, Alabama, and Mississippi, and west to Kentucky, Missouri, Tennessee, Arkansas. Texas and Louisiana plants are considered to belong to a different species, Trillium texanum, formerly treated as a variety of Trillium pusillum.
Threat Impact Comments
The primary and continual threat to this species non-native plant and animal species (feral hogs). Deer predation is also a primary threat (pers. comm. Trillium working group 2019). Threats include clear-cutting of mixed bottomland hardwoods, opening up of habitat for grazing, and habitat loss due to housing and industrial development (Southern Appalachian Species Viability Project 2002).
Ecology & Habitat

Diagnostic Characteristics

Similar to another dwarf trillium, Trillium nivale, a species mainly of the midwest. T. pusillum differs from T. nivale by its sessile, or nearly so, bracteal leaves, its wider flattened filaments, and its fruit wing-angled along the carpel sutures rather than obtuse-angled (Kral in Robinson, 1980). T. nivale grows on limestone-derieved and base-rich substrates, while T. pusillum grows on acid soils.

Habitat

Alluvial woods, savannah/nonriverine swamp forest ecotones, savannahs (NC, SC); upland woods, mixed mesophytic hardwood forest (AR, MO, TN); rocky soil of open fields (KY); low moist woods, bogs, and streambanks (TX); dampwoods, wooded swamps (MD, VA); thicket in well-drained soil and open areas at approx. 4,000 ft (VA/WV line). Information needed for other states (AL, LA, MS, OK).

Reproduction

Trillium seeds have an elaiosome, an oily, lipid-rich attachment that is highly attractive to ants. The ants carry the seeds to their nest, eat the attachment, and leave the seeds in tunnels in their nests (FNA 2002a, Leege et al. 2010). The seeds later germinate en masse (Case and Case 1997). Wait et al. (2005) found that seeds are also dispersed by harvestmen spiders. Yellow jackets (Vespula spp.) and other wasps are similarly attracted to the elaiosome. Yellow jackets are documented seed dispersers for three species (T. catesbaei, T. cuneatum, T. undulatum) (Zettler et al. 2001). Ants carry the seeds an average of about 1m whereas yellow jackets disperse seeds an average of 1.4m (Chafin 2010, Zettler et al. 2001). Long distance dispersers include mammals, such as white-tailed deer (Odocoileus virginianus) and woodchucks (Marmota monax) (Chafin 2010, Vellend et al. 2006). Similarly, it is suspected that elk (Cervus canadensis) and mule deer (Odocoileus hemionus) of the western U.S.A. are capable of dispersing seeds over long distances (Bartuszevige and Endress 2008).

All Trillium have rhizomes but the frequency of asexually reproduction varies (Chauhan et al. 2019, FNA 2002a, Ohara 1989).

Trillium seeds exhibit a somewhat unique kind of dormancy called deep simple double morphophysiological dormancy, meaning they require two winters and one summer to complete dormancy break. After dispersal, roots (radicles) emerge in the first spring and leaves (epicotyls) begin growing in the second spring. The result is that Trillium seeds are generally about 1.5-2 years before they are non-dormant. If root emergence does not occur during the first spring, the next opportunity for root emergence would be the third spring and epicotyl emergence would occur during the fourth spring after dispersal (Walck et al. 2005). Age to maturity, or flowering, is variable and has been recorded from 4 to 20 years depending on growing conditions (Case and Case 1997).
Terrestrial Habitats
Forest/WoodlandForest - HardwoodWoodland - HardwoodWoodland - MixedSavanna
Palustrine Habitats
FORESTED WETLAND
Other Nations (1)
United StatesN4
ProvinceRankNative
MissouriS2Yes
TennesseeS2Yes
OklahomaS1Yes
KentuckySNRYes
AlabamaS2Yes
South CarolinaSNRYes
MississippiS1Yes
VirginiaS2Yes
North CarolinaS1Yes
ArkansasS3Yes
MarylandS2Yes
West VirginiaS1Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentLarge (31-70%)Slight or 1-10% pop. declineHigh (continuing)
4 - Transportation & service corridorsRestricted (11-30%)Moderate - slightHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesPervasive (71-100%)Moderate or 11-30% pop. declineHigh (continuing)

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Plant Characteristics
DurationPERENNIAL, Long-lived
Economic Value (Genus)Yes
Roadless Areas (2)
Arkansas (1)
AreaForestAcres
Brush HeapOuachita National Forest4,205
West Virginia (1)
AreaForestAcres
Dry River (WV)George Washington National Forest7,331
References (25)
  1. Andre, C.S., A.D. Wait, W.B. Anderson. 2005. Ecology of three populations of the rare woodland perennial, <i>Trillium pusillum</i> Michaux (Liliaceae) in southwestern Missouri. Missouriensis 26:7-21.
  2. Bartuszevige, A.M., and B.A. Endress. 2008. Do ungulates facilitate native and exotic plant spread? Seed dispersal by cattle, elk and deer in northeastern Oregon. Journal of Arid Environments 72: 904-913.
  3. Case, F.W. and R.B. Case. 1997. Trilliums. Timber Press, Portland Oregon.
  4. Chafin, L. G. 2010d. Species account for <i>Trillium persistens </i>for Georgia Department of Natural Resources. Online. Available: georgiawildlife.com/sites/default/files/uploads/wildlife/nongame/pdf/accounts/plants/trillium_persistens.pdf.
  5. Chauhan, H., A. Bisht, I. Bhatt, A. Bhatt, and D. Gallacher. 2019. <i>Trillium </i>- toward sustainable utilization of a biologically distinct genus valued for traditional medicine. The Botanical Review 85(3): 252-272.
  6. Fernald, M.L., and A.C. Kinsey. 1943. Edible Wild Plants of Eastern North America. Idlewild Press, Cornwall-on-Hudson, NY. xiv+452 pp.
  7. Flora of North America Editorial Committee (FNA). 2002a. Flora of North America north of Mexico. Vol. 26. Magnoliophyta: Liliidae: Liliales and Orchidales. Oxford Univ. Press, New York. xxvi + 723 pp.
  8. Gleason, H.A. 1952. The new Britton and Brown illustrated flora of the northeastern United States and adjacent Canada. 3 volumes. Hafner Press, New York. 1732 pp.
  9. Gleason, H.A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. New York Botanical Garden, Bronx, New York. 910 pp.
  10. 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.
  11. Klest, S.M. 2002. Propagation Protocol for Western Trilliums. Native Plants Journal 3(1):22-23.
  12. Leege, L. M., J. S. Thompson, D.J. Parris. 2010. The Responses of Rare and Common Trilliums (<i>Trillium reliquum</i>, <i>T. cuneatum</i>, and <i>T. maculatum</i>) to Deer Herbivory and Invasive Honeysuckle Removal. Castanea 75(4): 433-443.
  13. Lewis, Walter H., and Memory P.F. Elvin-Lewis. 1977. Medical Botany: Plants Affecting Man's Health. John Wiley and Sons, New York, New York. 515 p.
  14. Ohara, M. 1989. Life history evolution in the genus Trillium. Plant Species Biology 4:1-28.
  15. 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.
  16. Rahman, S., M. Ismail, M. Khurram, I. Ullah, F. Rabbi, and M. Iriti. 2017. Bioactive steroids and saponins of the genus <i>Trillium. </i> Molecules 22(12): 2156.
  17. Robinson, A.F., Jr., ed. 1980b. Endangered and threatened species of the southeastern United States including Puerto Rico and the Virgin Islands. U.S. Forest Service General Rept. SA-GA 7.
  18. Schilling, E.E., A. Floden, J. Lampley, T. S. Patrick, and S. B. Farmer. 2017. A New Species in <i>Trillium</i> subgen. <i>Delostylium</i> (Melanthiaceae, Parideae). Phytotaxa 296(3):287–291.
  19. Southern Appalachian Species Viability Project. 2002. A partnership between the U.S. Forest Service-Region 8, Natural Heritage Programs in the Southeast, NatureServe, and independent scientists to develop and review data on 1300+ regionally and locally rare species in the Southern Appalachian and Alabama region. Database (Access 97) provided to the U.S. Forest Service by NatureServe, Durham, North Carolina.
  20. Steyermark, J.A. 1963. Flora of Missouri. Iowa State Univ. Press, Ames. 1728 pp.
  21. Timmerman-Erskine, M., J. Ballenger, R. Dute and R. Boyd. 2003. Allozyme investigation of the <i>Trillium pusillum</i> Michaux complex (Trilliaceae): taxonomic and conservation implications. Journal of the Torrey Botanical Society 130(1): 1-10.
  22. Trillium workshop group. 2019. , L. L. Gaddy, A. Floden, A. Frances, A. Highland, D. Leaman, T. Littlefield, C. Meredith, S. O'Bryan, L. Oliver, E. Schilling, A. Schotz, A. Walker, K. Wayman. Status assessment workshop at Mt. Cuba Center, Oct. 21-23, 2019.
  23. Vellend, M., J. Myers, S. Gardescu, and P. Marks. 2003. Dispersal of <i>Trillium</i> seeds by deer: Implications for long-distance migration of forest herbs. Ecology 84(4):1067-1072.
  24. Walck, J.L., J.M. Baskin, C.C. Baskin, and S.N. Hidayati. Defining transient and persistent seed banks in species with pronounced seasonal dormancy and germination patterns. Seed Science Research 15: 189-196. DOI: 10.1079/SSR2005209
  25. Zettler, J. A., T. P. Spira, and A. A. Craig. 2001. Yellow Jackets (<i>Vespula</i> spp.) Disperse <i>Trillium</i> (spp.) Seeds in Eastern North America. American Midland Naturalist 146(2):444-446.