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Weed Identification

Virginia Tech College of Agriculture and Life Science Virginia Cooperative Extension

broadleaf signalgrass

Family

Poaceae

Scientific Name

Urochloa platyphylla
Weed photograph 1
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Weed photograph 8
Weed photograph 9

Synonyms (former Scientific Names):

Brachiaria platyphylla
Brachiaria extensa
Paspalum platyphyllum

Habit

A spreading summer annual, reaching a height of approximately 3 ft, that commonly is found growing along the ground but with tips ascending (decumbent growth habit). Roots are fibrous and capable of rooting at the lower stem nodes.

Leaves

Leaf blades are overall short and wide in appearance, approximately 1 1/2 to 6 inches long and 6-15 mm wide. Leaf blades are widest near the base and taper to the apex. Leaves are rolled in the bud and without hairs on either leaf surface except on margins and in the collar region. The ligule is a narrow membrane fringed with hairs, 1/2 to 1 mm long. Leaf sheaths are hairy. Leaves may have a crinkle on one side of the leaf blade while the other is smooth.

Identifying Characteristics

The relatively broad and short leaves of this grass weed make it easily distinguishable from other grasses. Additionally, the lack of hairs on the leaf blades, rooting stem nodes, and flattened spikelets help to identify broadleaf signalgrass from most other grasses found in similar environments. Stems of broadleaf signal grass are prostrate, branching and bent at the nodes. These plants often root at the lower stem nodes, and therefore are most commonly seen growing along the ground with some tips ascending (decumbent). Seedlings will often have leaf sheaths that are maroon-tinged and hairy throughout. Leaf blades are without hairs, except for those that occur on the margins. Leaf blades may also be maroon-tinged, with a fringed membranous ligule. Broadleaf signalgrass is similar to Texas panicum (Urochloa texana) in growth habit and appearance. However, the leaves of broadleaf signalgrass are not covered with short, soft hairs like those of Texas panicum.

Flower Seed Head

Seedhead a raceme, approximately 12 inches long and 4 inches wide. Each seedhead has 2 to 6 'branches', approximately 1 to 3 1/2 inches long. Spikelets on the seedhead are somewhat flattened in appearance.

Seed Fruit

Seed are light brown in color and are approximately 3-4mm in length.

Where Found

Broadleaf signalgrass height is found most commonly as a weed of agronomic crops of the southeastern and south-central United States.

Leaf Hair on Upper Surface

Varies: 
no hairs, 
hairs on basal half only

Leaf Arrangement

rolled in bud

Mature Leaf Width

6 to 15 mm

Stem

flat or oval

Seedhead

spike

Root Structure

fibrous

Life Cycle

summer annual

Auricle

not present

Ligule

Varies: 
membrane, 
hairy

Ligule Length

Varies: 
less than 1 mm, 
1-2 mm

Plant Type

Grass