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field mustard, turnip

black mustard

Habit Plants annual or biennial, glabrous or sparsely pubescent basally, rarely glaucous. Plants annual, hirsute at least basally.
Stems

3–12(19) dm.

3–20(31) dm.

Basal leaves

and lowermost cauline (5)10–40(60) × 3–10 (20) cm;

margins entire, dentate, or pinnatisect, with terminal lobes larger than 1–6 lateral lobes on each side, petiolate.

and lowermost cauline 6–30 × 1–10 cm;

margins lyrate-pinnatifid to pinnatisect; terminal lobes larger than 1–3 lateral lobes on each side, petiolate.

Inflorescences

fruiting pedicels ascending to divaricate; (5)10–25(30) mm.

fruiting pedicels straight; slender; erect to ascending, subappressed to rachis; (2)3–5(6) mm.

Flowers

sepals oblong; (3)4–6.5(8) mm, ascending;

petals obovate; (5)7–10(13) × (2.5)3–6(7) mm, bright yellow, rarely pale or whitish yellow;

claws 3–7 mm;

anthers oblong, 1.5–2 mm;

filaments 4–6(7) mm;

lateral curved at base;

styles obsolete.

sepals oblong, 4–6(7) mm, spreading to ascending;

petals ovate; (6)7.5–11(13) × (2.5)3–4.5(5.5) mm, yellow;

claws 3–6 mm;

filaments 3.5–5 mm;

lateral curved at base.

Fruits

divaricate to ascending; terete; (2)3–8(11) cm × 2–4(5) mm, valvular segments (1.3)2–5(7.5) cm, 8–15-seeded per locule;

valves with prominent midveins; terminal segments conical; (0.3)1–2.5(3.5) cm; seedless or rarely 1-seeded, sessile.

4-angled, subappressed to rachis; (0.5)1–2.5(2.7) cm × (1.5)2–3(4) mm, valvular segments (0.4)0.8–2(2.5) cm, 2–5(8)-seeded per locule;

valves with prominent midveins, slightly torulose; terminal segments style-like; (1)2–5(6) mm; seedless, sessile.

Seeds

1–1.8 mm in diameter.

globose, 1.2–2 mm in diameter.

Upper cauline leaves

ovate to lanceolate, 2–8(12) × 0.8–3 cm, bases amplexicaul or auriculate, sessile.

lanceolate to linear-oblong; to 5 × 1.5 cm, bases not auriculate, petiolate.

2n

=20.

=16.

Brassica rapa

Brassica nigra

Distribution
[WildflowerSearch map]
[BONAP county map]
[WildflowerSearch map]
[BONAP county map]
Discussion

Abandoned fields, roadsides, disturbed areas, gardens. Flowering Apr–Oct. 0–1500 m. BW, Casc, Col, CR, Est, Lava, Sisk, WV. CA, ID, NV, WA; worldwide. Exotic.

Brassica rapa includes many cultivars. These are recognized as varieties or subspecies, including turnip (ssp. rapa), Chinese mustard or bok choy (ssp. chinensis), and Chinese cabbage or petsai (ssp. pekinensis).

Roadsides, disturbed areas, fields, orchards. Flowering Apr–Oct. 0–1000 m. Col, CR, Lava, Owy, Sisk, WV. CA, ID, NV, WA; worldwide. Exotic.

Source Flora of Oregon, volume 2, page 459
Ihsan Al-Shehbaz
Flora of Oregon, volume 2, page 459
Ihsan Al-Shehbaz
Sibling taxa
B. elongata, B. juncea, B. napus, B. nigra, B. oleracea
B. elongata, B. juncea, B. napus, B. oleracea, B. rapa
Synonyms Brassica campestris
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