Sorghum halepense

Johnson Grass

Field view of Sorghum halepense, common name Johnson Grass.

Sometimes Johnson Grass panicles are contracted and straw-colored.

Leaves of Sorghum halepense are huge compared to most grasses. The whole plant is often 6 or 8 feet tall.

Another field view of Johnson Grass.

The inflorescence of Sorghum halepense is usually reddish brown.

Close view of some spikelets exagerates its awns, which are sometimes bent (I photoshopped them--kinda fake-looking).

Before anthesis, the seedheads are rather condensed, sometimes almost spike-like.

In this closer view you can see the shapes of the spikelets.

This is a single large rhizome, growing beneath the ground surface and reaching out to form one or more new plants. This is a non-seed method of reproduction.

How to Identify Johnson Grass

  This is a common roadside and field perennial grass that is usually much larger and bulkier than most other grasses. It starts small (and can be confusing then) but rapidly grows from 6 to 12 feet tall. It occurs in every county of Arizona. The large, foot-long reddish brown seedheads with their small oval seeds are almost unmistakable.

Similar Species

  The commercial Sorghum, Sorghum bicolor, is occasionally found as an escapee in COCO, MAR, PIM, PIN, and SAN. It hybridizes with Johnson Grass. The chief difference is that S. bicolor is bigger and is an annual plant that has no rhizomes. If you must identify it, you will have to collect the roots and check for rhizomes while in the field. I am happy just saying that all similar plants are Johnsongrass.