Ball-mustard

Myagrum paniculatum Linnaeus, Sp. Pl. 2: 641. 1753

Plants sparsely to moderately pubescent, fruits glabrous. Stems (1.4-)2.5-7.5(-9) dm. Basal leaves shortly petiolate; blade oblanceolate to oblong, 2-7.5 cm × 5-20 mm. Cauline leaves: blade lanceolate, narrowly oblong, or linear-lanceolate, (1.5-)2.5-7(-9) cm × (2-) 3-15(-25) mm, apex acute or acuminate, surfaces sparsely pubescent, trichomes mostly forked. Fruiting pedicels straight or slightly curved upwards, (4-)6-10 (-14) mm. Flowers: sepals 1.5-1.7 × 0.5-0.7(-1) mm; petals 2-2.5 × 0.5-0.7(-1) mm; filaments 1.5-2 mm; anthers 0.2-0.4 mm. Fruits (1.7-)2-2.2 × (2-)2.2-2.5 mm; style slender, 0.5-0.9 mm. Seeds 1.2-1.4 × 1-1.1 mm. 2n = 14.

Flowering May-Sep. Fields, grassy mountain slopes, plains, roadsides, cultivated fields; 0-1000 m; introduced; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., Que., Yukon; Alaska, Conn., Ind., Maine, Mass., Mich., Minn., Mont., N.H., Ohio, Pa., Vt.; Europe; Asia; n Africa; introduced also in South America (Argentina), Australia.