Forage and Grain Crops
Agronomy 105's Weed ID
Sudangrass
Sudangrass was introduced into the United States from the tropical regions of the Eastern hemisphere.  It is an annual grass that grows from 3 to 6 feet tall and is used for silage and emergency pastures.  Sudangrass reproduces by seed only.
The seeds of Sudangrass look somewhat like those of Johnson-grass however, they will be larger.  The color of these seeds will vary from dark purplish to bright red or even a very light tan.  Johnsongrass seed is smaller and will have a knob on the end of the rachilla, whereas in Sudangrass these knobs are almost always broken off.