Barbarea orthoceras (American Yellow Rocket)
|Also known as:||American Winter Cress, Northern Winter-cress|
|Life cycle:||biennial, short-lived perennial|
|Habitat:||part shade, sun; moist sandy or rocky soil; meadows, shores, open woods, rocky slopes, cliffs, gravel pits, sandbars|
|Bloom season:||May - July|
|Plant height:||8 to 24 inches|
|Wetland Indicator Status:||GP: OBL MW: OBL NCNE: OBL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
Pick an image for a larger view. See the glossary for icon descriptions.
Stalked flowers in rounded to cylindrical clusters 1 to 1½ inches across at the tips of branching stems and arising from leaf axils. Flowers are ¼ to 1/3 inch across with 4 yellow petals, 6 yellow stamens and a stout style.
4 yellow to yellow-green sepals, about 1/8 inch long, surround the base of the flower. Clusters elongate as the plant matures, with flowers blooming at the tip and fruit forming along the stem below.
Leaves and stems:
Leaves are basal and alternate. Near the base of the plant they are deeply lobed with a large rounded lobe at the tip and 1 to 4 pairs of small oblong-elliptic lobes widely spaced on the stalk. Basal leaves are up to 2½ inches long and up to 1 inch wide, the stalk ½ to 3 inches long or sometimes longer. Lobe edges can be somewhat wavy and shallowly lobed or with a few coarse teeth.
Leaves become smaller as they ascend the stem and typically have a pair of largish lobes (auricles) at the base of the stalk that clasp the stem and have scattered hairs around the edge. Uppermost leaves may be less finely divided with little or no stalk. Stems are single or multiple from the base, branched in the upper plant, ridged or angled, purplish or green with purple streaks or stripes, and hairless.
Fruits are slender, erect to ascending, green pods up to 1½ inches long that are straight to slightly curved. The pods hold numerous tiny, brown, oval to oblong seeds.
American Yellow Rocket is a circumpolar species native to North America and Asia, and is more common in the western states and into Canada. In Minnesota it is primarily found in the Arrowhead region near the rocky shore of Lake Superior. It is far less common here than the look-alike, non-native Garden Yellow Rocket (Barbarea vulgaris). While there are small differences in flower size, leaf shape and fruit arrangement, the most obvious difference is the fringe of sparse hairs on at least some leaf auricles, where Garden Yellow Rocket is completely hairless.
Please visit our sponsors
Native Plant Nurseries, Restoration and Landscaping Services ↓
- American Yellow Rocket plant
- American Yellow Rocket plant
- fruiting American Yellow Rocket plant
- mid-stem leaf
- more flowers
Photos by K. Chayka taken in Cook County. Photos courtesy Peter M. Dziuk taken in Lake County.
Have you seen this plant in Minnesota, or have any other comments about it?
on: 2018-05-22 11:48:09
Growing in the lawn a few feet from the road near the Mississippi River (area hasn't been mowed yet this year). It takes a magnifying glass to see the fringe of sparse hairs along the auricles. Flowers opening 5/21/18.
on: 2020-05-06 10:47:00
Spotted at Trout Brook Nature Reserve (Saint Paul) and Oheyawahi (Mendota Heights). Blooming 1st week of May 2020.
on: 2020-05-06 10:53:39
Michelle, more likely what you saw was B. vulgaris, garden yellow rocket
on: 2021-05-18 18:45:27
Surely this plant is becoming invasive? I see it everywhere this year! Tom
on: 2021-05-18 21:18:14
Thomas, all that yellow you see on the roadsides this time of year is the non-native weed Barbarea vulgaris, garden yellow rocket.
on: 2022-05-19 20:12:42
I'm pretty sure there is a patch of this blooming in our alley in south Minneapolis - Auricles have visible hairs. It appeared out of the blue - I don't remember it there last year.