Flower:

Single flower on a long slender stalk arising from leaf axils on branching stems. The flowers are about 1/3 inch long, tubular with 4 or 5 white lobes. The lower 3 are notched and all of similar size. The upper is sometimes completely fused as 1 lobe that is larger than the lower 3, or notched into 2 lobes smaller than the lower. Fine yellow hairs are at base of the upper lobes. The tube is yellowish green with fine brown parallel veins. Inside the tube are 2 fertile and 2 sterile stamens. The 5 sepals at the base of the flower are finely hairy, narrowly lance-like and about half the length of the tube, with 2 similar bractlets that can be longer than the sepals.

Leaves and stem:

Leaves are ¾ to 2 inches long, ¼ to 3/8 inch wide, lance to spatulate shaped, narrowing from mid-leaf toward base then widening as they clasp the stem, with a few sparse teeth around the tip end, covered in short fine hairs. Stems are erect and many branched, also covered in short fine hairs,

Notes:

Hedge-hyssop is widely scattered throughout the state along muddy stream banks, lake margins and wet meadows and is likely more common than reported, as its small size and insignificant features do not call attention to itself. The plant is similar to False Pimpernel (Lindernia dubia), which is overall hairless with blue-violet flowers.