Rorippa calycina (Engelm. ex Hayden) Rydb.:
China (Asia)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Rorippa calycina is a regional endemic only known to be extant from Wyoming, plus historic records on the Yellowstone River in Montana and downstream in North Dakota. There is also a collection record of it on the Arctic coast of Canada's Northwest Territories that is apt to represent accidental waterfowl dispersal.

The combination of having a perennial rhizomatous habit, yellow flowers, and egg-shaped siliques separate this species from all other members of the genus. The persistent sepals are also diagnostic.

Comments: Disturbed (but not recently) sandy shores of lakes and streams.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: More than 20 sites known in Wyoming, most located since 1980; the species has been colonizing banks of artificial reservoirs. Also known from 1 historic record in North Dakota, 3 historic records in Montana and 2 recent records that may be extirpated, plus one accidental introduction in NWT.

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Known originally from only a few sites in Montana and Wyoming, and adjacent western Nebraska and North Dakota; only known to be extant and persisting in Wyoming where in recent decades (especially since 1980) this species may have become more abundant, due to its ability to colonize banks of artificial reservoirs in this region. Altogether, a few dozen occurrences are now known (1997). Reports under this name from California, Oregon, and Washington are instead a different species, Rorippa columbiae.

Global Short Term Trend: Increase of 10 to >25%

Comments: Possibly increasing due to ability to colonize shores of artificial reservoirs; Rollins (1993) suggests that "it appears that the provision of suitable habitats by the construction of reservoirs has provided for an unusual increase in the number of populations of this species."

Comments: A key question is the interchangeability of reservoir habitat for free-flowing riparian habitat. The accompanying change in water levels may threaten the taxon if there is not a seedbank or unaffected seed source; or may open up additional habitat. Tamarisk competition and shoreline developments are potential threats.

Biological Research Needs: Determine habitat requirements, particularly responses to wa ter level changes.

Comments: Distinct; as treated here, following Kartesz (1994), excludes Rorippa columbiae, by some included here as var. columbiae).