black mustard

Rhamphospermum nigrum

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

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• fruit appressed to stem, or at least partially so
• may be less appressed later in the season [IF]
• fruit has 4 raised ribs, giving each a square cross section [IF]
• fruit 1–2.5 cm long, 2–3 mm wide
• valves have 1 vein each [HPB]
• terminal segment 2–5 mm, thin and seedless
• stem 30–200 cm
• stem hairs unclear: hairy only higher up [MCW] or stiff hairy below [Jepson]
• basal leaves are pinnately lobed, more or less toothed [MCW]
• cauline leaves are smaller [MCW] with a tapered base, not clasping
• stem is much more leafy than shortpod mustard (Hirschfeldia incana) [IF]
• vegetation is glossy dark green; compare to shortpod mustard (Hirschfeldia incana)
• flower buds often overtop open flowers [IF]
• sepals and buds are glabrous [IF]; compare to shortpod mustard (Hirschfeldia incana)
• very common, but also commonly IDed by mistake [IF]

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Chris’s observations: 7 (1 is research grade)

Locations:

• Coyote Hills RP: 3
• Coyote Lake / Harvey Bear Ranch CP: 2
• Ed R. Levin CP
• Máyyan 'Ooyákma Coyote Ridge OSP

Months:

• Mar.: 1
• Apr.: 5
• May: 1

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Not all sites agree about the scientific name:

• Rhamphospermum nigrum → iNaturalist
• Brassica nigra → Calflora – CalPhotos – Jepson eFlora – FNA

Bay Area species: iNaturalist – Calflora