Giant foxtail

June 11, 2015

Setaria faberi Herrm Poaceae (Grass family)

Life cycle

Erect summer annual.

Leaves

Leaves have dense short hairs on the upper surface. They are soft, rolled in the bud and up to 12 inches long. Leaf sheaths have hairs along the margins.

giant foxtail upper leaf surface
Giant foxtail upper leaf surface.

Ligule

Hairy

Stems

Erect, mostly 3- to 7-foot-tall stems are branched and clump-forming at the base. Stems are usually round but are occasionally flattened in cross section.

giant foxtail collar region
Giant foxtail collar region.

Flowers and fruit

The seedhead is a dense, cylindrical-shaped, foxtail-like panicle with green to purple bristles. Highly nodding seedheads are capable of producing large numbers of oval to egg-shaped, yellowish brown seeds.

Reproduction

Seeds.

giant foxtail seedhead
Giant foxtail seedhead.

Similar weeds

Green foxtail (S. viridis L.)
Differs by having leaves that are hairless and rough to the touch, shorter stature – reaching only three feet tall, erect to slightly nodding panicles.

green foxtail collar region green foxtail seedhead
Green foxtail collar region (left) and seedhead (right).

Yellow foxtail (S. glauca [L.] Beauv.)
Differs by having long, wispy hairs on the upper leaf surface near the stem, a panicle with yellowish brown bristles and a yellow to light brown seedhead at maturity.

yellow foxtail seedling yellow foxtail collar region yellow foxtail seedhead
Yellow foxtail seedling (left), collar region (middle), and seedhead (right).

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