ANNUAL SUMPWEED
File Size: 104 KB
 
Iva annua  L.
Barton County, Kansas
Annual
Height: 8-48 inches
Family: Asteraceae - Sunflower Family
Flowering Period:   August, September,October
Also Called: Annual marshelder.
Stems: Usually erect, usually branched.
Leaves: Cauline, mostly opposite, distal sometimes alternate; petiole .2 to 1.2 inch; blade deltate to ovate, lanceolate, or elliptic, 1.2 to 6 inches long, .4 to 3.2 inches wide, base acute to acuminate or truncate, margins coarsely serrate, surfaces rough.
Inflorescences: Heads discoid, sessile in spike-like arrays, solitary in axils of linear to ovate bracts, containing both pistillate and staminate florets, pistillate florets peripheral, staminate central; peduncles short; involucral 1/6 to 1/5 inch across, involucral bracts 3-5, subtending the mature achenes.
Flowers: Pistillate florets 3-5; corolla white, tubular, 1/50 to 1/25 inch. Staminate florets 8-12; corolla white, funnelform, 1/12 to 1/10 inch, lobes 5.
Fruits: Achenes brown to brownish black, obovoid to pyriform, 1/12 to 1/6 inch, pappus absent.
Habitat: Moist ground in disturbed sites
Distribution: East 6/7 of Kansas
Origin: Native

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