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Weed Identification

jointhead arthraxon

Family

Poaceae

Scientific Name

Arthraxon hispidus

Other Common Names:

small carpgrass
hairy joint grass
joint-head grass

Synonyms (former Scientific Names):

Arthraxon ciliaris
Phalaris hispida

Habit

graminoid

Leaves

Leaves are broad and taper to a point, approximately 2 1/2 inches long by 3/4 inches wide. Leaf bases encircle the sheath and have conspicuous hairs along the margins.Leaves are without auricles and have a thin membranous ligule (often with hairs) that is from 1 to 2 mm long.

Identifying Characteristics

A low-growing annual grass with short, wide leaves.Jointhead arthraxon is primarily a weed of pastures, hay fields, and ditches. A low-growing grass with short, wide leaves with bases that encircle the stem and have hairs along the margins. This weed may be confused with Deer-Tongue Grass, but has spikelets instead of a panicled seedhead like that of deer tongue grass. Additionally, the leaves of deer-tongue grass are generally much longer than those of jointhead arthraxon, and the stems of deer-tongue grass do not root at the nodes like those of jointhead arthraxon.Jointhead arthraxon may also be confused with Common or Asiatic Dayflower (Commelina communis), which also has broad grass-like leaves and a prostrate growth habit. The two can be distinguished by the presence of a distinct ligule on jointhead arthraxon, which is not present on common or asiatic dayflower.

Flower Seed Head

Many spikelets that resemble 'fingers'

Where Found

found primarily in the piedmont areas of North Carolina, Virginia, Georgia, Florida, Alabama, Mississippi, and Tennessee.

Leaf Hair on Upper Surface

hairs from base to tip

Leaf Arrangement

rolled in bud

Mature Leaf Width

Varies: 
less than 5 mm
6 to 15 mm

Stem

round

Seedhead

spike

Life Cycle

summer annual

Auricle

not present

Ligule

Varies: 
membrane
hairy

Ligule Length

Varies: 
less than 1 mm
1-2 mm
2-3 mm

Plant Type

Grass