Virginia Tech Weed Identification Guide

Dallisgrass: Paspalum dilatatum

dallisgrass1-15c.jpg (241948 bytes) Weed Description: A clump-forming perennial with a tall membranous ligule and a seedhead with many finger-like branches.   Dallisgrass is primarily a weed of turfgrass and lawns, but also occurs in pastures, roadsides, and occasionally agronomic crops.
Seedlings:  Leaf blades may be short hairy when young, but most older plants only have hairs in the collar regions.   Leaves are rolled in the bud, have a tall, membranous ligule, and are without auricles.

Leaves:  Leaves are rolled in the bud and lack auricles.  Leaf blades range from 4 to 12 inches in length and 6 to 15 mm in width.  Leaves are without hairs except for several long silky hairs that occur in the collar region.  Ligules are membranous and from 1 to 3 mm tall.

Stems:  Sheaths are compressed and mostly lack hairs.  Sheaths are often tinted red with age.  Plants can tolerate mowing but may also grow to a height of 5 feet when allowed to do so.

Roots:  Fibrous roots and short rhizomes.

Flowers:  The seedhead is produced on a terminal stalk that may reach 5 feet in height but is more commonly shorter due to close mowing.  The seedhead is a raceme that has 3 to 5 finger-like spikes branching from the center.  Each spike is from 2 to 4 inches long and contains 4 rows of spikelets that are each 3 to 4 mm long and covered with black silky hairs.

Identifying Characteristics: A perennial grass with short rhizomes, a tall ligule, and leaves with hairs near the collar only.  The seedhead of dallisgrass may be confused with that of Broadleaf Signalgrass (Brachiaria platyphylla), however broadleaf signalgrass has much shorter, wider leaves and a much shorter ligule that is a fringe of hairs.