Lepidium ruderale L., Brassicaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 16 (Go to the risk assessment)

Common name(s): [more details]

Chinese: zhu mao du xing cai

English: narrow-leaved pepperwort, peppercress, peppergrass, roadside peppergrass

French: cresson puant, passerage des décombres

Spanish: lepidio de hoja estrecha

Habit:  herb

Description:  "Herbs annual or biennial, (5-) 10-35 (-55) cm tall, fetid, puberulent with terete papillate trichomes. Stems erect or ascending, branched above. Basal leaves with petioles 1-2 (-3) cm; leaf blade (1 or) 2- or 3-pinnatisect, (1.5-) 3-5 (-6) x  (0.5-) 0.7-2 (-2.5) cm, glabrous except for ciliate margin; ultimate lobes oblong, entire or rarely toothed, acute. Upper cauline leaves sessile; leaf blade linear, (0.4-) 1-2 (-3) cm x  (0.3-) 0.5-2.5 (-3.5) mm, sparsely pubescent, base cuneate, not auriculate, margin usually entire, ciliate, apex obtuse to subacute. Fruiting pedicels slender, divaricate, straight or slightly curved, (1.5-) 2-4 (-5) mm, puberulent all around. Sepals oblong, 0.5-0.9 (-1) x  0.2-0.4 mm, puberulent with papillate trichomes, margin and apex white. Petals absent, sometimes rudimentary and to 0.4 mm. Stamens 2; filaments 0.7-0.8 mm; anthers ovate, 0.1-0.2 mm. Fruit broadly elliptic, (1.5-) 1.8-2.5 (-3) x  1.5-2 (-2.3) mm, narrowly winged apically; apical notch 0.1-0.2 mm; style to 0.1 mm, included in apical notch. Seeds brown, oblong or ovate-oblong, 1-1.5 x  0.6-0.7 mm, wingless, finely papillate; cotyledons incumbent"  (Flora of China online).

"Annual or biennial, more or less foetid, 20-30 cm, single-stemmed, much branched above, glabrous or sparsely covered with short spreading hairs. Basal leaves 2-3 x pinnate, long-petiolate, forming a loose rosette or withering early. Caulline leaves pinnate with narrow entire segments; upper segments narrow, oblong, sessile. Fruiting pedicels slender, ascending, 2-4 mm. Siliculae ovate or broadly elliptical, narrowly winged above, 2-2.5 x 1.5-2 mm; septum 1.5-2 x 0.5 mm" (Davis, 1965; p. 281).

Habitat/ecology:  Roadside, waste places, from sea level to 1500 m (Davis, 1965; p. 281).

Propagation:  Seed

Native range:  Throughout Europe and southwest Asia (Davis, 1965; p. 281).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	Tassin, Jacques (2005)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced	MacKee, H. S. (1994) (p. 44) Vouchers cited: Baumann 6146, MacKee 2451, MacKee 9942
New Zealand (offshore islands) Kermadec Islands	Raoul Island	introduced invasive	Sykes, W. R. (1977) (pp. 102-103)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Sandy soil, pastures; 300-1100 m. Xinjiang.
Japan Japan	Japan	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Honshu Naturalized
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 183)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (Washington)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 212)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (continental except west coast) United States (other states)	United States (other states)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (continental except west coast) United States (other states)	USA (Florida)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Control:  If you know of control methods for Lepidium ruderale, please let us know.