umbrella plant
noun
1.
rhizomatous perennial herb with large dramatic peltate leaves and white to bright pink flowers in round heads on leafless stems; colonizes stream banks in the Sierra Nevada in California
2.
late blooming perennial plant of shale barrens of Virginia having flowers in flat-topped clusters
3.
African sedge widely cultivated as an ornamental water plant for its terminal umbrellalike cluster of slender grasslike leaves