Editing Alternanthera (section)

==Ecology==
Many species have been reported as noxious weeds, including ''A. angustifolia'', ''A. caracasana'', ''A. denticulata'', ''A. nana'', ''A. nodiflora'', ''A. paronychioides'', ''A. philoxeroides'', ''A. sessilis'', ''A. tenella'', and ''A. triandra''.<ref name=tan/> The most important species is [[Alternanthera philoxeroides|alligator weed]] (''A. philoxeroides''), a South American aquatic plant that has spread to other continents.<ref name=tan/> It is a weed of many kinds of [[agriculture|agricultural crops]], it is an [[invasive species]] that degrades native habitat, and its dense mats of vegetation clog waterways, slowing shipping and increasing [[flood]]ing.<ref name=tan/> ''Alternanthera'' plants are known to produce [[allelopathy|allelopathic]] compounds that injure other plants, including crops.<ref name=tan/>

[[Biological pest control]] agents now in use to reduce alligator weed infestations include the [[Agasicles hygrophila|alligator weed flea beetle]] (''Agasicles hygrophila''), the [[Amynothrips andersoni|alligator weed thrips]] (''Amynothrips andersoni''), and the [[Arcola malloi|alligator weed stem borer]] (''Arcola malloi'').<ref name=tan/>