▁were ▁introduced . ▁This ▁is ▁an ▁example ▁of ▁how ▁human ▁interaction ▁with ▁nature ▁can ▁bl ur ▁the ▁boundary ▁of ▁what ▁is ▁considered ▁nature . ▁ ▁Another ▁category ▁of ▁plant ▁has ▁histor ically ▁been ▁car ved ▁out ▁for ▁we eds . ▁Though ▁the ▁term ▁has ▁fallen ▁into ▁dis f avor ▁among ▁botan ists ▁as ▁a ▁formal ▁way ▁to ▁categor ize ▁" us eless " ▁plants , ▁the ▁inform al ▁use ▁of ▁the ▁word ▁" we eds " ▁to ▁describe ▁those ▁plants ▁that ▁are ▁de emed ▁worthy ▁of ▁elim ination ▁is ▁illustr ative ▁of ▁the ▁general ▁t endency ▁of ▁people ▁and ▁soci eties ▁to ▁seek ▁to ▁alter ▁or ▁shape ▁the ▁course ▁of ▁nature . ▁Similarly , ▁animals ▁are ▁often ▁categor ized ▁in ▁ways ▁such ▁as ▁domestic , ▁farm ▁animals , ▁wild ▁animals , ▁p ests , ▁etc . ▁according ▁to ▁their ▁relationship ▁to ▁human ▁life . ▁ ▁Anim als ▁as ▁a ▁category ▁have ▁several ▁characteristics ▁that ▁generally ▁set ▁them ▁apart ▁from ▁other ▁living ▁things . ▁Anim als ▁are ▁e uk ary otic ▁and ▁usually ▁mult ic ell ular ▁( although ▁see ▁My x oz oa ), ▁which ▁separ ates ▁them ▁from ▁b acter ia , ▁arch ae a , ▁and ▁most ▁prot ists . ▁They ▁are ▁heter ot roph ic , ▁generally ▁dig est ing ▁food ▁in ▁an ▁internal ▁chamber , ▁which ▁separ ates ▁them ▁from ▁plants ▁and ▁alg ae . ▁They ▁are ▁also ▁distinguished ▁from ▁plants , ▁alg ae , ▁and ▁fung i ▁by ▁lack ing ▁cell ▁walls . ▁ ▁With ▁a ▁few ▁exceptions