Distribution: British Columbia to southern Oregon, east to Newfoundland and Virginia,
Habitat: Marshes, bogs, wet meadows and standing water, lowlands to mountain valleys; uncommon in the Pacific Northwest.
Flowers: August - September
Conservation Status: Sensitive in Washington (WANHP)
Slender, glabrous, usually single-stemmed perennials, 3-10 dm. tall, the stem not much thickened at the base and sometimes without thickened roots.
Leaves all cauline, the lower and middle ones dissected, with narrowly-linear, usually entire segments 0.5-4 cm. long and 0.5-1.5 mm. wide; the upper leaves reduced, with fewer segments or undivided, many of them bearing axillary bulbils.
Umbels frequently wanting, or present but not maturing fruit; umbels compound, the rays 1-2.5 cm. long, involucre wanting; involucel of several narrow bractlets; calyx teeth evident; petals 5, greenish-white.
Stylopodium depressed; fruit orbicular, glabrous, 1.5-2 mm. long, the ribs broader than the narrow intervals.