Regularity: Regularly occurring
Regularity: Regularly occurring
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: Seasonally flooded sandy shores and mudflats of lakes, streams, and riverbanks and margins of reservoirs, ponds, and lakes (FNA 2010).
Number of Occurrences
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.
Life History and Behavior
Produces large numbers of seeds and spreads by rhizomes (Fertig and Welp 1998).
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
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.
Names and Taxonomy
Comments: Distinct; as treated here, following Kartesz (1994), excludes Rorippa columbiae, by some included here as var. columbiae).
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