Sinapis arvensis (Wild Mustard) - photos and description





Upper stem leaf in above photo.

Lower stem leaf in above photo.

Basal leaf in above photo

Lower stems and undersides of leaves are rough hairy.

General: Annual plants more or less hirsute, stems may be purple where they join the main stem.

Flowers: Flowers bright yellow in terminal clusters. We measured a flower at 15 mm diameter.

Leaves: Stem leaves alternate. Upper leaves clasp the stem, coarsely toothed. We measured the upper stem leaf highlighted in the photo above at 38 mm long by 25 mm wide. Leaves mid stem and lower leaves lyrate-pinnatifid with two basal lobes and a large terminal lobe. Leaf mid stem measured at 75 mm long by 40 mm wide. Basal leaf blade measured at 95 mm long by 38 mm wide.

Fruit: Pods are ascending and cylindrical in profile. They are sparingly hairy to bristly hairy. We measured a pod at 30 mm long by 2 mm wide, the pod's stalk 2 to 3 mm long, and the pod's beak at 9 mm long, Budd's Flora and Flora of Alberta list the beak as about half as long as the pod. The beak is flat (two-sided).

Height: Height listed in Budd's Flora to 80 cm, we measured plants to 56 cm tall.

Habitat: Fields, roadsides, waste ground.

Abundance: Common.

Origin: Introduced.

Synonym: Listed in some of the field guides we use as Brassica kaber.

How to identify this plant: 1) Flowers bright yellow 10 to 15 mm in diameter. 2) Lowest leaves  lyrate-pinnatifid with two basal lobes and a large terminal lobe. 3) Plants more or less hirsute 4) Pods cylindrical 2-5 cm long (Budd's Flora) 5) Pod stalks less than 1 cm long (Taxonomic Reminder for Recognizing Saskatchewan Plants).

When and where photographed: Photos taken July 22nd, waste ground in our home city of Regina, SK.