fortplanta sig betyder på engelska

procreate [procreated, procreating, procreates]▼(to beget)
verb
[UK: ˈprəʊ.krɪeɪt] [US: ˈproʊ.krɪeɪt]

propagate [propagated, propagating, propagates]▼(to have young or issue)
verb
[UK: ˈprɒ.pə.ɡeɪt] [US: ˈprɑː.pə.ˌɡet]