IUCN threat status:

Not evaluated

Comprehensive Description

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This native perennial plant is 4-7' tall and little branched, except for a few stems developing from the middle to upper leaf axils. The central stem is light green, glabrous, 4-angled, and strongly winged. The opposite leaves are up to 6" long and 3" across, while their petioles are up to 2" long. The leaves are lanceolate-ovate or cordate-ovate, medium to dark green, and hairless or nearly so; their margins are coarsely serrated. At the apex of a plant, young vegetation may be slightly pubescent. The central stem and major secondary stems terminate in individual spikes of flowers. Each spike is about 4-16" long and ¾–1" across; the length of each spike is highly variable depending on the size of each plant and its maturity. The flowers are densely crowded together all around the spike, although only a few flowers are in bloom at the same time. Each flower consists of a tubular corolla about 1/3" long and a tubular calyx about 1/4" long. The pale yellow corolla has 2 upper lobes, 2 lateral lobes, and a single lower lobe that is the largest in size. These lobes are short and rounded. The light green calyx has 5 teeth and several veins along its sides; it is hairless or mostly hairless. Each flower has 4 stamens that are strongly exerted from the corolla and a divided style. The blooming period occurs from mid-summer to early fall and lasts 1-2 months. Individual flowers are short-lived. At maturity, each flower is replaced by 4 nutlets. The root system is fibrous and rhizomatous. Vegetative colonies are often produced from the rhizomes.


Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© John Hilty

Source: Illinois Wildflowers

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