Brassicaceae, the mustard family.
Plant: Branching plant, to 6' high, sparsely leafed except at base, with elongating, terminal clusters of bright yellow flowers. Annual.
Flowers: Yellow, about 1/2" across, with four petals, and four narrow sepals, in elongating clusters (racemes) at the ends of the several branches.
Leaves: Alternate, stalked, lower ones lobed and toothed, ovate in overall outline, 1"-3"; upper ones smaller, more lanceolate, often unlobed.
Fruit: A narrow, beaked capsule, square in cross-section, 1/2" long, and closely pressed to the stem.
Habitat: Fields, waste areas, roadsides.
A European immigrant, one of several yellow mustards in our area distinguished by
characteristics of the leaves and fruit.
The young leaves can be cooked and eaten, and the seeds are used in condiments.
Where to find it:
I have found this plant only occasionally in the park; the common yellow mustard is
winter cress (Barbarea vulgaris), easily distinguished by fruit that stick
out from the stem and distinctly different, mostly sessile leaves.