Victorin's water-hemlock (Cicuta maculata) COSEWIC assessment and status report: chapter 2

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Species information

Victorin’s water-hemlock (Cicuta maculata var. victorinii) is a perennial plant of the parsnip family (Apiaceae). The taxon has undergone few taxonomic changes since it was described by Fernald.  Boivin (1966) considers it to be a variety of Cicutamaculata, a view that has been accepted by all subsequent authors, except Gleason and Cronquist (1991), who do not accept the validity of the taxon.  Variety victorinii is distinguished from var. maculata by its reniform to ovoid-cordate fruit with prominent lateral ribs and obscure dorsal ribsand its linear-lanceolate leaflets.  Although the writer has noted that gradation occurs in the form of fruits between Victorin’s water hemlock and the typical variety (var. maculata), the distinctness of Victorin’s water-hemlock as a unique endemic of the intertidal zone of the St. Lawrence R. estuary is here recognized on the basis of the study by Mulligan (1980). The study by Mulligan (1980), based in part on plants grown from seed, stressed the importance of ripe fruits in identifying the varieties of Cicuta maculata.

Distribution

Victorin’s water-hemlock is confined to Canada and is considered endemic to the upper St. Lawrence estuary.  It occurs only in the freshwater and slightly brackish intertidal zones.  To date, the plant is known from 39 localities.  The southwest limit of its range is at Sainte-Anne-de-la-Pérade and the northeast limit is at Saint-Jean-Port-Joli.  A disjunct population at Chandler (in the Gaspé) was inventoried by the author during the revision of water hemlock specimens, but the locality remains to be confirmed.

Habitat

Victorin’s water-hemlock occurs in tall, dense, prairie cordgrass beds in the mid- and upper intertidal zones.  It prefers thick surface deposits (over 15 cm) of fine or mixed texture (never coarse), with highly variable stoniness, ranging from no stones to very stony.  Plant densities are much lower in sectors covered by gravel and pebbles. In several localities, the water pH ranges from 8.0 to 8.5, and the surface deposits consist of fragmented schist and watery silt, with a pH of 7.5.  In the mid-littoral zone or on thin substrate, Victorin’s water-hemlock sometimes grows in open, short grass beds.

Biology

Victorin’s water-hemlock is a herbaceous perennial that flowers from June to early September.  Fruiting begins in August and continues until September.  The seeds are surrounded by a spongy fruit coat that keeps the fruits buoyant until they are thoroughly saturated with water.  This aids in the dissemination of fruits by water.  The umbels and fruit are sometimes covered with hundreds of aphids, the impact of which is unknown.

Population sizes and trends

Since Legault’s report (1986), 30 new populations have been discovered and the species is currently known from 33 extant localities. The localities are classified as follows:  four localities with a site quality index A (>100 plants and little disturbance), 10 localities with a site quality index B (51-100 plants and slight habitat disturbance or >100 and significant disturbance), six localities with a site quality index C (10-50 plants and little disturbance or 51-100 with significant disturbance), 13 localities with a site quality index D (<10 plants with little disturbance or 10-50 plants with significant disturbance), two extirpated populations and four historic localities.

Limiting factors and threats

There are several actual or potential threats to Victorin’s water-hemlock: its limited habitat prevents it from colonizing other sites outside the freshwater and slightly brackish intertidal zone; fruit predation can adversely affect recruitment; the mowing of the grass beds and flower picking prevents reproduction; ice scouring and the spring ice break-up tear up plants and parts of the river bank, fluctuating water levels can cause river bank erosion; poor water quality can result in plant mortality; the Agricultural Abuses Act requires property owners to tear up all water hemlocks growing on their property, regardless of variety status; and filling of the river banks results in habitat loss and could destroy populations.  However, the most serious threats to the species are human trampling and recreational vehicle traffic (ATVs). 

Special significance of the species

Victorin’s water-hemlock is of interest to scientists because of what they can learn from it about the origin of the endemic flora of the estuarine beaches of the St. Lawrence River.  In addition, some water-hemlocks have recognized medicinal properties (cicutoxin), but no studies have yet been conducted on Victorin’s water-hemlock.

Existing protection or other status designations

Victorin’s water-hemlock was designated a species of special concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 1987.  The organization NatureServe has assigned it a global rank of G5T2 (species globally widespread and secure with the subspecies being imperiled), a Canadian rank of N2 (imperiled nationally) and imperiled (S2) in Quebec (NatureServe 2001).

The populations of Saint-Michel-de-Bellechasse (Anse Saint-Vallier), L’Islet, and Saint-Jean-Port-Joli (Anse de Trois-Saumons) are protected because they are located in the Saint-Vallier, L’Islet and Trois-Saumons migratory bird sanctuaries.  The Grosse Île population is also protected because it is located in the Grosse Île and the Irish Memorial National Historic Site.  In addition, the organization Conservation de la nature Québec owns part of the site on which the Saint-Vallier populaton occurs.

In Quebec, Victorin’s water-hemlock was designated “threatened” in February 2001 and is now protected under the Act Respecting Threatened or Vulnerable Species.  However, water-hemlock (Cicuta maculata) is considered a weed under the Agricultural Abuses Act (R.S.Q. A-2).  Its habitat is protected against the most serious threat to its survival by the Regulation Respecting Motor Vehicle Traffic in Certain Fragile Environments (R.S.Q., c. Q-2, r. 2.2).  Further, the Quebec policy respecting the protection of lakeshores, riverbanks, littoral zones and floodplains seeks to maintain and improve water quality by ensuring a minimum adequate level of riverbank protection.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Species

Any indigenous species, subspecies, variety, or geographically or genetically distinct population of wild fauna and flora.

Extinct (X)

A species that no longer exists.

Extirpated (XT)

A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A species facing imminent extirpation or extinction.

Threatened (T)

A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)*

A species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)**

A species that has been evaluated and found to be not at risk.

Data Deficient (DD)***

A species for which there is insufficient scientific information to support status designation.

 

 

*

Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.

**

Formerly described as “Not In Any Category”, or “No Designation Required.”

***

Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994.