Paspalum dilatatum

Dallis Grass

Field view of Paspalum dilatatum or Dallis Grass.

Seedheads have 2 to 8 branches.

Sparce seedheads of Dallis Grass, named for a botanist, not the city of Dallas, Texas.

The seedheads are rough-looking partly because they have minute hairs on the sides.

Rows of round spikelets are on one side (top branch). The lower view shows the flat branch.

These spikelets are in anthesis, showing the extended purple stigmas as well as the hairs.

Leaves are almost as long as the culms.

Branches have tiny silky hairs and purple stigmas.

Two old, brown branches. The minute hairs collect debris, making them look shabby.

How to Identify Dallis Grass

  The flat spikelets ("seeds") with pointy tips are very round in shape. They are almost 1/8 inch in diameter and in two perfect rows. The branches are few and flattened. The rachis is fully visible below the seed rows if you turn the branch over. The key differences are the very round spikelets and that no other Paspalum has the fine hairs that collect debris and spider webs. These hairs are minute, so look closely with a hand lens. Fortunately, the hairless three are all quite uncommon.

Similar Species

  Three of Arizona's five Paspalum species are relatively rare and confined to extreme southeast Arizona counties. The other common Arizona species, Paspalum distichum, (Knotgrass) has pointed oval spikelets and no fine hairs. Also, unlike P. dilatatum, it usually has just two branches at the very top.