Wild mustard , Charlock
Sinapis arvensis

Description
Upright annual, seed-propagated weed with a short taproot, originates from Eurasia.

Characteristic Features
Characteristic yellow flowers.

Cotyledons
Vigorous, inverse-cordate, petiolate, strongly sinuate at the tip.

Stems
Erect, with ramified branches especially at the top, roughly haired below, up to 60 cm (23.62 inch) high.

Leaves
Lower leaves petiolate, lobed, or sinuate-dentate, nearly lyre-formed.
Upper leaves ovate-oblong, only short-petiolate to sessile, irregularly dentate, usually undivided.
The first true leaf has a broad, rounded tip and shallow indentations along its margins.