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North Dakota's

Federally Listed Endangered, Threatened, and Candidate Species – 1995

Hayden's Yellow-cress (Rorippa calycina)

GIF -- species photo gif--species map

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Status: Former Candidate (Note: As of February 28, 1996, this species is no longer listed as a Candidate species. However, it remains a species of management concern.)

Historical Status:
In North Dakota, Hayden's yellow-cress is known only from the Yellowstone River in northwestern McKenzie County. It was collected by Dr. Ferdinand Hayden in 1854. Hayden described the species as growing in the "sandy bottoms of the Yellowstone River, between Fort Sarpy and Fort Union." Since Hayden, only one other collection has been made in the Yellowstone River Valley. This collection was from Custer, Montana in the late 1800's.

Present Status:
Hayden's yellow-cress is known from less than a dozen isolated locations in western North America. To date, it has been documented from the 3 western states of Wyoming, Montana, and North Dakota. An isolated population of this species has also been reported in the Northwest Territories of Canada. The specimens that were recorded in Montana and North Dakota have not been relocated by botanists while the Wyoming populations are increasing.

Hayden's yellow-cress is a riparian species found along sandy shores of lakes and streams near the high water line.

Life History:
Hayden's yellow-cress is a perennial which means that a single plant may live for several years. It flowers from May to July along riverbanks.

Aid to identification:
Hayden's yellow-cress is a low perennial herb with weak erect branched stems (4-16 inches long). The leaves are coarsely toothed to shallowly lobed. The lower leaves have petioles (leaf stalks), the upper ones lack petioles and tend to clasp the stem. Flowers are borne in a branched inflorescence that becomes more open as the fruit matures. Each flower has 4 opposite sepals and 4 opposite yellow petals. Like all members of its family, Hayden's yellow-cress has 6 stamens of which the outer 2 are shorter than the inner 4. Its soft-hairy fruits are 1-2 times long as wide.

Reasons for decline:
If Hayden's yellow-cress is still present in North Dakota, this species may be threatened by increased recreational river use. Changing water levels may also threaten existing populations; however, it may also open up additional habitat.

Notify a natural resources agency on any suspected Hayden's yellow-cress.

Very little is known about the life history and ecology of Hayden's yellow-cress. Hayden's yellow-cress is a member of the mustard family from which originate several food products, including the common mustard. Hayden's yellow-cress was named after Dr. Ferdinand Hayden, a geologist with the U.S. Geological Survey. Dr Hayden's survey party explored the Yellowstone River in 1871. His work in the Yellowstone country helped in the movement to establish Yellowstone Park. Dr Hayden's explorations also found many of the vast mineral resources of western North Dakota.

Flora of the Great Plains, by the Great Plains Associstion, 1986. Published by the University Press of Kansas. North Dakota Sensitive Plant Guide, by the U.S.Forest Service, 1991.

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