hairy crabgrass
Family
PoaceaeScientific Name
Digitaria sanguinalis
Other Common Names:
purple crabgrass
large crabgrass
Synonyms (former Scientific Names):
Syntherisma sanguinalis
Panicum sanguinale
Habit
Large crabgrass germinates in the spring and competes with turf during the summer months. Crabgrass begins germinating when sustained soil temperatures are 55 degrees F and moisture is available. In Virginia (USA) plants usually begin germinating mid April to early May in the mountains, late March to late April in the piedmont, and early March to mid April on the coastal plain. Plants compete with turfgrass during the summer, set seed in the fall, and die with first frost.
Leaves
Large crabgrass leaves are densely hairy on both surfaces. Hairs are long but stiff and erect. The collar area and stems are hairy and the ligule is a large membrane. Stems tend to trail along the ground and root at nodes.
Identifying Characteristics
Fat cotyledon (seed leaf), hairy on all leaves and stems, large membraneous ligule and three to five-branched seedhead on slender stalk.
Flower Seed Head
Seedheads are borne on slender stalks and consists of three to five spikelets in an open arrangement.
Seed Fruit
Seeds are flat and narrow; about 1.5 mm wide and 5 mm long.
Where Found
Large crabgrass is widely distributed and one of the most economically important weeds of turfgrass. Plants can be found in the lawn, under close cut such as a putting green, and in tilled areas such as a home garden.
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
flat or oval
Seedhead
multiple spikes
Root Structure
fibrous
Life Cycle
summer annual
Auricle
not present
Ligule
membrane
Ligule Length
Varies:
less than 1 mm,
1-2 mm,
2-3 mm
Plant Type
Grass