Annual herb 10 cm - 0.5 m tall Stem: single or multiple, upright, branched above, purplish near base, ribbed. Flowers: in compact, branched clusters (racemes), which are borne terminally on the stems. Flower stalks to 1 cm long (longer in fruit). Sepals four, not touching (free), spreading to upright, whitish yellow along the margins, 2 mm long, 1 mm wide, egg-shaped. Petals four, white, 3 mm long, twice as long as sepals. Stamens six. Fruit: a pod (silicle), upright, 1 - 1.7 cm long and wide, roundish, tips deeply notched (deeper than wide), winged all around. Fruit stalks ascending, to about 2 cm long. Seeds numerous. Basal leaves: in a rosette, stalked, to 8 cm long, to 2 cm wide, spatula-shaped or oblong or narrowly reverse egg-shaped with a narrowly lobed base and rounded tip, shallowly toothed or lobed, soon wilting. Leaf stalks winged. Stem leaves: alternate, stalkless, clasping, about 6 cm long, about 2 cm wide, oblong to lance-shaped with pointed lobes at base, sometimes coarsely toothed.
Similar species: No information at this time.
Flowering: late March to late July
Habitat and ecology: Introduced from Europe. A weed found in cultivated fields, waste ground, disturbed areas, and along roads and railroads. It is also found as a weed in nursery plots.
Occurence in the Chicago region: non-native
Etymology: Thlaspi is the Greek word for cress. Arvense means "of farmed or cultivated land."
Glabrous annual or winter-annual 1-5 dm; cauline lvs sessile, oblong to lanceolate, entire or few-toothed, bearing at base 2 narrow, divergent, acute auricles 1-5 mm; fls 3 mm wide, the pet twice as long as the sep; mature pedicels ascending; frs orbicular to broadly elliptic, 10-17 mm, winged all around, deeply (2-3 mm) notched; seeds concentrically ridged-striate, numerous in each locule; 2n=14. Native of Europe, commonly established in waste places throughout much of N. Amer. Apr.-June.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Duration: Annual Nativity: Non-Native Lifeform: Forb/Herb General: Herbaceous annuals, to 80 cm tall, stems erect, unbranched or branched distally, herbage glaucous to glabrous throughout, plants with pungent, watery sap, often fetid when crushed. Leaves: Alternate, basal and cauline; basal leaves not in a rosette, blades oblanceolate, spatulate, or obovate, 1-5 cm long and 4-23 mm wide, margins entire, repand, or coarsely dentate, bases attenuate or cuneate, apices rounded, borne on petioles 0.5-3 cm long, cauline leaves oblong, 0.5-8 cm long and 2-25 mm wide, apices rounded, obtuse, or subacute. Flowers: White, with 4 petals forming a cross, petals 2-5 mm long and to 2 mm wide, narrowing to a clawlike base about 1 mm long, apices obtuse or with a notch at the apex (emarginate), sepals 4, free, 1.5-3 mm long and 1-1.5 mm wide, stamens 6 with 4 long and 2 short, filaments to 2 mm long, anthers to 0.5 mm long, ovary solitary and superior, ovules 6-16 per ovary, generally 2-chambered with a septum connecting 2 parietal placentas, styles solitary, persistent, style 0.1-0.3 mm long, flowers borne in elongated racemes at branch tips. Fruits: Obovate or suborbicular siliques dehiscent into 2 valves and a septum, flattened, 0.5-2 cm long and 5-20 mm wide, wings broad throughout, 1-1.5 mm wide basally, 3.5-5 mm wide apically, silique apices deeply emarginate with the notch about 5 mm deep, with Ecology: Introduced, found on roadsides, in fields, waste places, lawns, gardens, railroad tracks, stream banks, bluffs, thickets, slopes, floodplains, and woods, to 6,500 ft (1981 m); flowering March-August. Distribution: Widespread across almost all of the United States, including the southwest, not present in Alabama only. Notes: The relatively small and inconspicuous white flowers of this species turn into rather large, winged siliques. The keys to this species are the glabrous herbage, broadly winged fruits with the wing 3.5-5 mm wide apically, and the concentrically striate seeds. Look for this species in Arizona in Navajo and Coconino counties in Arizona. Ethnobotany: Infusion of plant taken for sore throats, leaves used for food, and seeds used in a variety of ways. Synonyms: Numerous, see Tropicos Editor: LCrumbacher2012