Shattercane (Sorghum bicolor):
Seedheads (below).
The membranous ligule at the collar region (below).
Johnsongrass:
The mature johnsongrass plant seems to be bothering this farmer in his field (below), he has every reason to be upset by this weed some misguided person introduced to the southern US long ago as a forage crop. This plant is quite tall and has a seedhead. Johnson grass reproduces by both seed and underground rhizomes (shoot tissue).
Below is the mature plant before it sets seed, notice the rhizomes and tillers.
Johnsongrass rhizomes (below) do not overwinter well north of about the Missouri-Iowa border. North of there farmers are very lucky not to have this nasty perennial weed.
But johnsongrass may be adapting farther north. Below is a rhizome piece found in Southern Ontario, Canada along Lake Erie in a warm, sunny field.
The membranous ligule of johnsongrass (below).
Almum grass:
The membranous ligule of almum grass (below).