- 1 per plant, variously spreading to erect, 7-50 cm, usually unbranched below the inflorescence, pubescent with appressed 2- and 3-branched hairs.
Stem and nodes.
- Basal and alternate, simple, sessile. Blades 2-8 cm long, linear to narrowly oblanceolate, the margins usually entire or the lower leaves commonly shallowly and broadly toothed, rarely pinnately lobed, pubescent with appressed 2- and 3-branched hairs.
- Panicles or racemes at branch tips.
- Sepals 4, 4-6 mm long, narrowly oblong, erect, green, hairy. Petals 4, 6-8 mm long, unlobed, light yellow to yellow, often grading to whitish at the base. Styles 0.5-2.0 mm long.
- Siliques, loosely ascending or spreading, 3-8 cm long, usually noticeably 4-angled in cross-section, pubescent with 2-branched hairs, the stalks 2-4 mm long, stout and about as wide as the fruits. Seeds 0.9-1.1 mm long, oblong-elliptic in outline, somewhat flattened, not winged.
- March - June.
- Roadsides, fields, pond margins, open disturbed areas.
- Native to Europe.
- This is an extremely variable plant. Established late-season specimens can be branched and bushy, as in the habit photo at the top of this page, but young plants early in the season can flower when only a few inches high with a single erect stem. The species is found in scattered locations in Missouri, most commonly in counties bordering the Missouri and Mississippi Rivers. It is also found across most of the continental U.S. It is easily identified by its generally weedy habit and small yellow flowers in the Brassicaceae pattern. It can be distinguished from its lookalikes by its stout fruit stalks, which are similar in diameter to the fruits (see image above).
Photographs taken at the Kansas City Zoo, 4-20-00, and at Eagle Bluffs Conservation Area, Boone County, MO., 4-11-04 (DETenaglia); also at Marais Temps Clair Conservation Area, St. Charles County, MO, 5-4-2015 and 4-9-2019 (SRTurner).
This plant can be weedy or invasive according to the authoritative sources noted below.This plant may be known by one or more common names in different places, and some are listed above. Click on an acronym to view each weed list, or click here for a composite list of
Weeds of the U.S.
Linnaeus, Demonstr. Pl. 17. 1753.
of leaves 2-rayed, mixed with fewer 3-rayed ones.
erect, unbranched or branched basally, (0.4-)1.5-4.5(-7) dm.
(often withered by fruiting), similar to cauline.
(proximal and median) petiolate and (distal) sessile, (petiole (0.3-) 0.5-2(-3) cm); blade [linear, narrowly oblanceolate, elliptic, or oblong, (1-)2-8(-11) cm × (2-)5-12(-17) mm, base attenuate], margins sinuate or coarsely dentate to denticulate or repand, (distal) entire or denticulate, (apex acute).
considerably elongated in fruit.
divaricate, stout, as wide as fruit, 2-4(-6) mm.
: sepals linear-oblong, 4-6 mm, lateral pair not saccate basally; petals yellow, narrowly oblanceolate to spatulate, 6-8 × 1.5-2 mm, claw 3-6 mm, apex rounded; median filaments 4-6 mm; anthers narrowly oblong, 0.8-1.3 mm.
widely spreading to divaricate-ascending, narrowly linear, straight or curved upward, somewhat torulose, (2-)3-8(-10) cm × 1.5-2 mm, 4-angled, not striped; valves with prominent midvein, pubescent outside, trichomes 2-rayed and, fewer, 3-rayed, often glabrous, sometimes pubescent inside; ovules (40-)50-80(-90) per ovary; style cylindrical or subclavate, stout, 1-4 mm, sparsely pubescent; stigma slightly 2-lobed, lobes as long as wide.
oblong, 1.1-1.5 × 0.6-0.7 mm; not winged or, rarely, winged distally.
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