Amaranthus tuberculatus (Moq.) J. D. Sauer — Overview

Tall Amaranth learn more about names for this taxon

Comprehensive Description

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This native annual plant is highly variable in size, ranging from 2-8' tall. Larger plants branch frequently and are broader at the base than at the top. The hairless stems are either round or ridged, and green or pinkish red. The hairless alternate leaves are up to 6" long and 1½" across. They are lanceolate, ovate-lanceolate, or oblong, with smooth margins and a somewhat shiny upper surface. The petioles are long and narrow, sometimes as long as the leaves, but usually shorter. The flowers are arranged in spikes, or narrow panicles of spikes, up to 1' long. These spikes may develop directly from the upper branches, or they may appear from the axils of the upper leaves.  Water Hemp is dioecious, with individual plants producing either staminate flowers (male) or pistillate flowers (female). Both types of flower are less than 1/8" long. Each staminate flower consists of 5 sepals, 5 stamens, and no petals; it is surrounded by 1-3 narrow bracts with pointed tips. Each pistillate flower consists of 0-2 sepals (usually 1), an ovary with 3 feathery styles, and no petals; it is surrounded by 1-3 narrow bracts with pointed tips. The bracts of both staminate and pistillate flowers vary in color from green to reddish pink. The flowers and bracts are arranged along the spikes more or less densely, sometimes occurring along the spikes in loose bunches. The blooming period usually occurs from late summer to early fall, and lasts about 1-2 months. There is no floral scent. The pistillate flowers are replaced by ovoid capsules that split cleanly in the middle to release the seeds. Each capsule contains a single small seed. The seeds are flat, round, shiny, and dark brown to black. The root system consists of a taproot. This plant spreads by reseeding itself. Cultivation


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© John Hilty

Source: Illinois Wildflowers

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