亜種[ashu] subspecies
異機種[ikishu] heterogenous equipment
異種[ishu] different kind (species, variety)
育種[ikushu] (plant) breeding
育種家[ikushuka] (plant) breeder

育種所[ikushujo] (plant) nursery
一種[isshu] species
一粒種[hitotsubudane] an only child
種違い[tanechigai] half-brother
艶種[tsuyadane] love affair

隔絶[kakuzetsu] isolation
気絶[kizetsu] faint
拒絶[kyozetsu] refusal
拒絶反応[kyozetsuhannou] (organ) rejection
空前絶後[kuuzenzetsugo] (so marvelous or horrible that it may be) the first and probably the last

懸絶[kenzetsu] great difference
根絶[konzetsu] eradication
謝絶[shazetsu] refusal
絶えず[taezu] constantly
絶える[taeru] to die out