A hairy, branching biennial growing to 2 feet tall, woollen breeches bears loose clusters of light blue, bell-shaped flowers. The lower leaves are shaped something like maple leaves and often have grayish or light green marks that look like water stains.
Flowers in loose groups (cymes), usually borne above the leaves; corolla with 5 shallow lobes, light blue; stamens purple-tipped, protruding slightly. Calyx with 5 sharp-pointed lobes; between each is a small, backward-curved appendage. Blooms April–July. Leaves alternate, thin, soft-hairy, palmately 5-lobed (like a maple’s), irregularly coarse-toothed, on long petioles. Lower leaves often with grayish or light green patches on upper surface, appearing water stained.
Similar species: Our other waterleafs lack the recurved appendages between the sepal lobes. Broadleaf waterleaf (H. canadense) grows only in east and east-central Missouri, is not hairy, and usually has leaves above the flower clusters. Virginia waterleaf (H. virginianum) is smooth, with pinnately lobed leaves (like a feather) with the pairs of lobes divided by a section of the midvein. Phacelias, such as Miami mist, have flowers in coiled cymes instead of branching or headlike cymes.