Ballhead waterleaf (Hydrophyllum capitatum) has short stems and a dense cluster of purple or whitish flowers that are typically much shorter than the basal leaves. These flowers open from May to July, depending on elevation. In bud, the sepals and petals appear coarsely fuzzy, prompting another common name of woollen-breeches.
Waterleaf prefers shady sites. This native perennial prefers shady to partly shady sites (but tolerates full sun) and loamy soil rich in organic matter. It can be a good addition to woodland gardens but spreads aggressively, so is not a great choice for small landscapes.