Round-leaved Greenbrier Great Lakes Plains population
Scientific Name: Smilax rotundifolia
Taxonomy Group: Vascular Plants
Last COSEWIC Assessment: November 2007
Last COSEWIC Designation: Threatened
SARA Status: Schedule 1, Threatened
Image of Round-leaved Greenbrier
Round-leaved Greenbrier is a woody climbing vine that can reach a length of over 4 m. Main stems bear stout, flattened prickles that enable the plant to climb over shrubs and into trees. The branches are rounded and the branchlets are sometimes squared. The leaves are 5 to 10 cm long, alternate, with an oval blade and a heart-shaped base. The leaves have no teeth or lobes. Plants are dioecious (male and female flowers are on separate plants). The small green flowers are clustered in rounded umbels; these umbrella-shaped inflorescences arise from the leaf axils. Only the female flowers, which are slightly smaller than the male flowers, produce fruit. Each female umbel produces a few blue-black berries, mostly with two seeds. In southern Ontario, this species can be confused with bristly greenbrier. Large, robust specimens of bristly greenbrier in particular can closely resemble Round-leaved Greenbrier; however, bristly greenbrier has dense thin prickles at the base of the stem and Round-leaved Greenbrier has no spines.
Distribution and Population
Round-leaved Greenbrier is found across much of eastern North America, from southwestern Nova Scotia to northern Florida and westward from Michigan and southwestern Ontario to eastern Texas. In Canada, it occurs near the north shore of Lake Erie in southern Ontario and in southwestern Nova Scotia. The plants in Ontario form the Great Lakes Plains population and those of Nova Scotia make up the Atlantic population. The Great Lakes Plains population is currently represented by 13 confirmed occurrences (sites) of the species. In all, the Ontario population consists of about 1000 to 5000 crowns, or individual plants. Each crown represents a multi-stemmed “individual” that may or may not be physically separated from other crowns. Population size and trends are poorly known because of the clonal nature of the species, which reproduces primarily by vegetative means, with new plants sprouting from horizontal underground stems called rhizomes. Many Ontario populations appear to have plants of only one sex and therefore cannot produce seed. It is conceivable that rescue, or immigration, can occur through seed dispersal from the United States. Although the potential frequency and distance of seed dispersal by birds have not been determined, long-distance dispersal appears to be possible, especially since large populations of Round-leaved Greenbrier occur in the United States south of Ontario very close to the Canadian border.
Round-leaved Greenbrier grows in a wide variety of habitats, from moist woods and rhododendron thickets to old fields. In Ontario, this species typically occurs in moist to wet wooded habitats, often on sandy soil. Temperatures in the Carolinian region where it occurs are generally moderate and precipitation is fairly uniform throughout the year. Seedling establishment may depend upon forest openings and surface disturbance.
The species is dioecious, meaning that male and female organs are contained on separate plants. In southern Ontario, the plant flowers from late May to mid-June. The female flowers depend on insect pollinators, mainly mosquitoes, to carry pollen to them from nearby flowers. Small flies, small bees and bumblebees appear to be potential pollinators as well. Only populations with both male and female plants produce fruit. The fruit matures in the fall, but some is typically retained over the winter to the next spring. Seeds are dispersed primarily by birds and mammals that eat the fruit. Seeds seem to require a cold period before germination can occur. Open areas in the woodland canopy may be required for seedlings to become established. However, clonal spread appears to be the primary means of reproduction, with new plants sprouting from rhizomes (horizontal underground stems that produce shoots above and roots below). Round-leaved Greenbrier therefore produces identical clones that can cover a large area over time. Individual clones may have a long life span.
In Ontario, the main threats to this species are destruction and alteration of the habitat and the small number of known populations. The species is under considerable threat from housing development, particularly in Essex County, where it is confined to small isolated woodlots surrounded by inhospitable agricultural land. Although the species reproduces vegetatively and is relatively long-lived, it is limited in Ontario because few sites have plants of both sexes. This limited capacity for seed production potentially reduces the amount of natural variability and therefore the adaptability of the Ontario populations. Urban expansion and the reduction of available habitat also threaten the sites in the Niagara region.
Federal ProtectionThe Round-leaved Greenbrier, Great Lakes Plains population, is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
Round-leaved Greenbrier and its habitat are protected under the Ontario Endangered Species Act, 2007. In Ontario, one population is in a city park and portions of another population are on property that belongs to Long Point Region Conservation Authority.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Round-leaved Greenbrier (Smilax rotundifolia), Great Lakes Plains population, in Canada
Status First posting on SAR registry
Carolinian Woodland Plants Recovery Team
Jarmo Jalava - Chair/Contact - Other
Phone: 705-760-2823 Send Email
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
6 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
Recovery Document Posting Plans
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