Family:
Poaceae
Toxins:
steroidal saponins
Flower Color:
  • flower color
Type:
forb
Found:
haybales, pastures, fields, waterside, wasteareas, savannas, forests, roadsides

Time of Greatest Risk

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Geographical Distribution

Fall panicum distribution - United States

Related Species

Fall Panicum

Panicum dichotomiflorum

Fall Panicgrass, Spreading Witchgrass, Spreading Panicgrass, Spreading Panicum, Sprouting Crabgrass, Kneegrass
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Fall panicum (Panicum dichotomiflorum) is a fibrous-rooted summer annual grass with a zigzagged growth pattern, due to bending at the nodes. Peak growth of fall panicum occurs between June and July, just before flowering and reproduces from seeds that mature in late summer and fall. Fall panicum thrives in wet open areas of fields, and tolerates flooding.

Fall panicum is distinguished by the following attributes:
  • Height: up to 7 ft (2.1 m)
  • Early growth: Emerge from the ground in April or early May; they are white, pale green or purplish smooth with an erect, slightly oval stem. It's basal stems grow from the enlarged lower nodes into an upright branching grass.
  • Root:Fibrous root system with stems capable of rooting at the nodes.
  • Stem: Hairless, round, sometimes glossy. Swollen and bent nodes, in different directions.
  • Leaves: Rolled in the shoot; ligule is a fringe of hairs and often fused at the base; leaf blades have a conspicuous midvein, smooth above but sometimes slightly hairy near the leaf tip or leaf base.
  • Flowers: Wide seedheads, with spreading panicle that turns purplish tint as it ages; individual yellow spikelets.
  • Look alikes: Looks very similar to Johnsongrass ( Sorghum halepense) and Barnyard grass ( Echinochloa crus-galli)) prior to development of seedheads.
Toxic components
Panicum species contain steroidal saponins. If large quantities of steroidal saponins are ingested by horses, it can lead to liver damage and secondary photosensitization.

History of poisoning cases
In 2006, 14 horses living in Virginia were poisoned from being fed Panicum hay containing large quantities of P. dichotomiflorum. These horses developed liver damage as a result of consumption of the toxins in P. dichotomiflorum. Five of the 14 affected horses were euthanized due to the extent of the resulting damage, and the other horses recovered. All horses that had been eating the hay had abnormally high aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), gamma glutamyl transferase (GGT), and alkaline phosphatase (ALP) activity.