Hoary Yellowcress

Herbs annual or biennial, (20-)30-95(-110) cm tall, densely villous or hirsute at least near base, sparsely so or subglabrous above. Stems erect, simple at base, branched above. Basal leaves rosulate, soon withered; petiole 1-7 cm; leaf blade lyrate-pinnatifid or subruncinate. Lower and middle cauline leaves sessile, lanceolate, oblanceolate, or oblong, 2.5-10(-15) × 0.4-2.5(-4.5) cm, villous or hirsute, lyrate-pinnatifid, with 2-7 lateral lobes on each side of midvein, base auriculate or amplexicaul, margin laciniate, irregularly serrate, repand, or entire, apex acute; uppermost leaves undivided, entire or obscurely denticulate. Racemes ebracteate. Fruiting pedicels ascending, (2-)4-12(-14) mm, straight, slender, glabrous or hirsute. Sepals oblong, spreading, 1.6-2.8 × 0.6-1.2 mm. Petals yellow, obovate or spatulate, (1.5-)1.8-3(-3.5) × 0.7-1.8(-2) mm, apex obtuse. Filaments 1.5-2.5 mm; anthers narrowly oblong, 0.5-0.6 mm. Ovules 60-85 per ovary. Fruit globose or subglobose, (2.5-)3.5-6(-6.5) × (2.3-)2.8-4(-4.3) mm; valves (3 or)4(-6), leathery, glabrous, not veined; gynophore 0.3-0.8(-1) mm; style stout, 0.5-1(-1.4) mm. Seeds dark reddish brown, oblong-ovate, 0.5-0.7 × 0.3-0.4 mm, reticulate. Fl. & fr. Mar-Aug. 2n = 16.

Heilongjiang, Jilin, Nei Mongol [Mongolia, Russia; North America (Alaska, N Canada)].

Forest borders, roadsides, moist areas, river banks; 100-2100 m.

Camelina barbareifolia de Candolle, Syst. Nat. 2: 517. 1821; Nasturtium barbareifolium (de Candolle) B. Fedtschenko (1912), not Baker (1877), nor Franchet (1888); Rorippa hispida (Desvaux) Britton var. barbareifolia (de Candolle) Hultén; Tetrapoma barbareifolium (de Candolle) Turczaninow ex Fischer & C. A. Meyer; T. kruhsianum Fischer & C. A. Meyer; T. pyriforme Seemann.

Rorippa barbareifolia, the hoary yellowcress, is a plant species reported from Manchuria, Inner Mongolia, Mongolia, Siberia, Alaska, Yukon and Saskatchewan. It grows in wet habitats (though not completely submerged). It can be found along forest borders, in ditches, on stream banks, etc.

Rorippa barbareifolia can easily be distinguished from other species in the genus by its multi-valved fruits. Rorippa barbareifolia fruits have 3-6 valves, usually 4, while other species generally have 2, rarely 3. The plants are annual herbs with yellow, 4-parted flowers.