SMOOTH CRABGRASS
File Size: 61 KB
 
Digitaria ischaemum   (Schreb. ) Schreb. ex  Muhl.
Konza Prairie, Riley County, Kansas
Annual
Height: 8-28 inches
Family: Poaceae - Grass Family
Flowering Period:   August, September
Culms: Ascending or erect from spreading bases, usually bent, slender.
Blades: Flat, .6 to 6+ inches long, 1/10 to 2/5 inch wide, midrib absent, often purplish, glabrous to very sparsely hairy near ligule.
Sheaths: Keeled, glabrous or with sparse hairs on upper margins.
Ligules: Membranous, short
Inflorescences: Racemes, 2-8, spike-like, 1.6 to 6 inches long, extending in different directions from a common point, terminating main inflorescence axis; rachis flattened, less than 1/20 inch wide, thin-winged.
Spikelets: Lanceolate-elliptic, 1/16 to 1/12 inch long, grouped in 2 rows on 1 side of raceme branch axis, 1-flowered, sessile or short-stalked, becoming dark brown or purplish-black; first glume absent or underdeveloped; second glume elliptic, 1/16 to 1/12 inch long, sparsely to densely pubescent with minute gland-tipped hairs; tip sharply pointed; sterile lemma about equal to second glume, 5-nerved, pointed; fertile lemma ovate-elliptic, pubescent; tip sharply pointed; margin thin, transparent.
Habitat: Moist, disturbed sites, stream banks, lake and pond margins, roadsides, open woods, fields, gardens, waste areas.
Distribution: Principally east 1/2 of Kansas.
Origin: Introduced from Eurasia
Comments: Smooth crabgrass forms loose tufts and is often a troublesome weed. It resembles hairy crabgrass Digitaria sanguinalis, but is less common.

Smooth crabgrass
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Konza Prairie, Riley County, Kansas
Smooth crabgrass spikelets
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Konza Prairie, Riley County, Kansas
Smooth crabgrass leaf
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Konza Prairie, Riley County, Kansas
Smooth crabgrass ligule
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Konza Prairie, Riley County, Kansas
Smooth crabgrass
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Konza Prairie, Riley County, Kansas
Smooth crabgrass
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Konza Prairie, Riley County, Kansas