Identification and Reproduction

Identification: 

• Johnsongrass is a perennial grass that grows up to 2.4 m tall. 
• Leaves are alternate, hairless, lanceolate and have a distinct white midrib. 

• Flowers are found in a loose purple panicle that can measure up to 50 cm in length. 

• Culms above ground appear bulb-like and swollen. 
• Rhizomes are fleshy, short and knotty. 

Reproduction: 

• This plant reporduces by rhizomes and seed. 
• It is a prolific seed producer. Each individual panicle produces hundreds of seeds. 
• Rhizome system is extensive and can reach to depths of 1.2 m. 
• Can resprout from fragmented rhizome parts. 
• Young plants that sprout from rhizomes grow much faster thatn seedlings. 

Habitat & Ecology

• It grows in crop fields, pastures, abandoned fields, right of ways, forest edges, streambanks and other disturbed areas. 
• Is very aggressive on exposed, rich, cultivated fields. 
• Johnsongrass is found on every continent except for Antarctica. 

Impacts

Social:

• Although edible, if an excessive amount of the foliage is consumed, it can kill cattle and horses. 
• Can also cause excessive bloating of other livestock. 
• Reduces pasture land and displaces crop species. 

Ecological:

• Grows and spreads rapidly, outcompeting and shading out native species.
• Dense rhizomatous mats prevent the establishment of trees. 
• Infestations dry and die in the summer and will be come a potential fire hazard. 

Management

Prevention is a high priority for this species. 

• Learn to identify this plant and report sightings. 
• Clean and remove any seeds that may attach to clothing, shoes, equipment and pets when leaving an infested site. 
• Refrain from moving unknown soil and plant matter. 

Resources

For more information check out the Bugwood Wiki datasheet on Sorghum halepense. 

Header photo (Hillebrand Steve).