Johnson grass

Johnson grass (Sorghum halepense) is a grass of the sorghum family. It is native to the Mediterranean region, but grows throughout Europe, the Middle East. The plant has been introduced to all continents except Antarctica and most larger islands and archipeligo. It reproduces by rhizomes and seeds.

Johnson grass has been used for forage and to stop erosion, but it is often considered a weed for the following reasons: 1. Foliage that becomes wilted from frost or hot dry weather can contain sufficient amounts of prussic acid to kill cattle and horses if it is eaten in quantity. 2. The foliage can cause 'bloat' in such herbivores from the accumulation of excessive nitrates; otherwise, it is edible. 3. It grows and spreads so quickly that it can 'choke out' other cash crops that have been planted by farmers.

In Argentina the plant is causing new problems as it is growing resistant to the popular herbicide glyphosate.