[Tansymustards: The Genus Descurainia East of the
Cascade Mountains of Oregon and Washington]
Cut-leaved Tansymustard, Mountain Tansymustard
Descurainia incisa
ssp. viscosa
Synonyms: Descurainia incana ssp. incisa, Descurainia incana ssp. viscosa, Descurainia incisa ssp. viscosa, Descurainia richardsonii ssp. incisa, Descurainia richardsonii ssp. viscosa, Descurainia richardsonii var. sonnei, Descurainia richardsonii var. viscosa
The photo above shows a close-up of the leaf of tansy mustard
as seen near the head of Kiger Gorge on the Steens Mt, southeastern Oregon.........June
25, 2000.
The
photo at right shows tansy mustard (var. viscosa) as seen near the head
of Kiger Gorge on the Steens Mt, southeastern Oregon.........June 25, 2000.
Characteristics:
Tansy mustard is an annual wildflower with some branching of
the erect stems which may rise from 20-100 cm high. The herbage is variable,
ranging from green and glabrous to woolly and covered with star-like hairs or
with gland-tiped hairs above. The lower leaves are pinnate-pinnatifid while
those above are pinnatifid with toothed or lobed margins. The lower leaves measure
2-10 cm long with segments from 1-3 mm wide while those above are reduced in
size.
The inflorescence is a dense raceme of pale to deep yellow flowers,
the sepals being 1-2.5mm long and the petals from 1.5-3.5 mm long. The slender
pedicels are spreading to strongly ascending and measure from 4-8 mm long. The
seed capsules are thin, linear siliques from 5-17 mm long and 1 mm wide, which
ascend or are erect. The mature pods may often be constricted between
seeds.
Habitat:
Tansy mustard is found on open ground from the lowlands to middle
elevations in the mountains.
Range:
Tansy mustard is found over much of western North America.
Mountain tansymustard in bloom along the Hanan Trail #142, Fremont-Winema National Forest........June 17, 2020.
The photo above shows a close-up of tansy
mustard (var. viscosa) as seen at Monument Rock in the Monument Rock
Wilderness of central Oregon..........July 6, 2002. Note the numerous
whitish gland-tipped hairs on the stem and the ascending seed pods which are
slightly constricted between seeds.
The photo above shows a close-up of a stem leaf of tansy mustard
(var. viscosa) as seen at Monument Rock in the Monument Rock Wilderness
of central Oregon..........July 6, 2002.
What appears to be cutleaf tansymustard blooming on steep talus slopes north of the day use area at Cottonwood Canyon State Park, Sherman County, Oregon........March 18, 2016. Note the siliques which are linear and curved inwards at the tip, rather than club-shaped.
Lower leaves of cutleaf tansymustard as seen along Forest Road 2901 near the junction with Oregon Highway 31, BLM lands about 1 mile east of Picture Rock Pass, Lake County, OR.........April 30, 2017.
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The photo above shows tansy mustard as seen
at Horsethief Butte State Park along the Columbia River in Washington..........March,
2000.
Paul Slichter
