Digitaria horizontalis

Species category

Weed

Common name

Jamaican crabgrass

Diagnostic characters

Planting unit

FloretFloret:
A small flower in a clustered inflorescence (e.g., sunflower, grasses). In grasses, a floret consists of the lemma, palea, stamens, and pistil.

Shape

EllipticElliptic:
Outline of an ellipse; greatest width midway sloping to an equally pointed apex and base.

Size

  • Length 1.5–2.5 mm
  • Width 0.5–0.8 mm
  • Thickness 0.4–0.7 mm

Color

Light brown with purple overtones

Texture

FloretsFloret:
A small flower in a clustered inflorescence (e.g., sunflower, grasses). In grasses, a floret consists of the lemma, palea, stamens, and pistil.
are smooth and glabrousGlabrous:
Lacking hairs or pubescence.
. GlumesGlume:
The pair of chaffy bracts that occur at the base of a grass spikelet, often completely enclosing it.
are pubescentPubescent:
Having hairs.
.

Lemma

GlabrousGlabrous:
Lacking hairs or pubescence.
, smooth, purple and finely striate

Palea

GlabrousGlabrous:
Lacking hairs or pubescence.
, smooth, purple, and finely striate

Other structures

The outer glumeGlume:
The pair of chaffy bracts that occur at the base of a grass spikelet, often completely enclosing it.
is short (about half the lemmaLemma:
One of two bracts of the grass floret; it is located on the side nearest the embryo and opposite the rachilla.
length).

Identification notes

Most of the glumeGlume:
The pair of chaffy bracts that occur at the base of a grass spikelet, often completely enclosing it.
pubescence is on the margin.

Noxious weed seed categories

Not listed

AOSA examination list

Not included

More information

For more information, see ISMA fact sheet, Digitaria spp.

Nomenclature

Family

Poaceae

Valid name

Digitaria horizontalis Willd.

 Digitaria horizontalis.  Florets with most of the glume pubescence on the margin. Photo by Julia Scher, USDA-APHIS-PPQ.
Digitaria horizontalis. Florets with most of the glume pubescence on the margin. Photo by Julia Scher, USDA-APHIS-PPQ.