plant - river

abandoned agricultural allelopathy aromatic asteraceae barley biodiversity branched broomweed capitula compositae congress crop crops culture dermatitis dog erect false famine farmland feverfew flea flower flowering grass herb herbaceous host hysterophorus infestation interference invader invasive land maria much mugwort nature parthenium pastures pest plant pubescent ragweed rangeland roadsides rosette santa stage weed whiteheads whitetop widespread wormwood