Plants of South Eastern New South Wales
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Brassica nigra
Black Mustard
Brassicaceae
Grassy areas, crops, roadsides, and waste areas. Mainly Sydney and within about 30 km of Bathurst. Occasionally elsewhere.
Introduced annual herb. Stems to 1 m high. Bristly at the base of the plant and becoming hairless above. Basal and lower leaves to 16 cm long, bristly on both sides, with 1–3 pairs of irregularly-toothed lobes. Stem leaves alternating up the stems, higher leaves entire, hairless, and often glaucous. Flowers bright yellow, with 4 petals each 7–9 mm long. Flowers in crowded clusters. Flowers Nov.-Jan. Seed cases erect and close to the stems, 1–2 cm long, (including the beak), 1–2 mm wide, 4-angled; slightly constricted between the seeds, midvein prominent. Beak 1–3 mm long, seedless. Stalk 3–8 mm long. Seeds dark red-brown.
PlantNET description: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Brassica~nigra (accessed 6 January, 2021)
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