Hydrophyllum capitatum, is a species of waterleaf known by the common name ballhead waterleaf. It is native to Western North America from British Columbia to Utah.
Hydrophyllum capitatum naturally occurs in the western region of the United States (California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington and Wyoming) as well as Alberta and British Columbia in Canada.
Hydrophyllum capitatum grows in extremely moist and shady environments in fine or medium textured soil. This plant tends to grow in open woodlands and slopes. It is salinity intolerant and lives in an environment that ranges in pH from 6.4 to 7.8. The ballhead waterleaf is a perennial plant adapted to a precipitation zone that ranges from 16 to 30m/yr and a temperature of -28 Fahrenheit and higher.
Individuals of this species are 10-40cm tall, hairy, erect herbs with solitary or few stems that are attached to 10 inch deep fibrous roots. The leaves are green and alternately arranged into 7 to 11 pinnately divided entire leaflets. The blades of the leaves are about 10cm wide and 15cm long. The flowers are sub-dichotomously branched and lay closer to the ground below the leaves (Hydrophyllum capitatum var. capitatum). However, a dwarf form of this plant occurs in northern Oregon and southern Washington where the flower heads are on long stalks above the leaves (Hydrophyllum capitatum var. thompsonii).
Flowers of Hydrophyllum capitatum, has whitish to purplish blue-coiled 5 to 9 cm bell-shaped corollas. Each flower also has 5 hairy calyx lobes. There are 5 long stamens per flower with anthers 0.6 to 1.3 mm long. The flowers bloom from March to July and obtain their purple color during this season. The fruit of the ballhead waterleaf are capsules with 1 to 3 seeds each.
The Indians and settlers cooked the leaves and the roots of plants belonging to the genus Hydrophyllum, which includes the ballhead waterleaf, for greens.