charlock

Rhamphospermum arvense

Member of genus Rhamphospermum
yellow mustards
mustard family (family Brassicaceae)
dicots (class Magnoliopsida)
yellow in flowering plants

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• fruit not appressed
• fruit linear: 2–4.5 cm long, 2.5–3.5 mm wide, glabrous
• valves have 3–7 prominent veins each [HPB]
• fruit does not have an obviously square cross section [IF]
• terminal segment is conical, inflated around 1 or 2 seeds [HPB] or 0 or 1 seeds [Jepson]
• stem 20–100 cm (occasionally much taller)
• stem is much more hairy than black mustard (Rhamphospermum nigrum) [IF], but occasionally glabrous [Jepson]
• basal leaves not in a rosette
• cauline leaves short-petioled, dentate
• uncommon

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Chris’s observations: none

Not all sites agree about the scientific name:

• Rhamphospermum arvense → iNaturalist
• Sinapis arvensis → Calflora – CalPhotos – Jepson eFlora – FNA

Bay Area species: iNaturalist – Calflora