▁H ons hu , ▁Sh ik oku ▁, ▁and ▁Ky ush u . ▁It ▁was ▁introduced ▁to ▁the ▁West ▁in ▁ 1 8 9 6 , ▁but ▁remains ▁rare ▁in ▁cultiv ation . ▁ ▁Description ▁ ▁Bet ula ▁gross a ▁is ▁con ical ▁in ▁outline , ▁but ▁its ▁most ▁distinct ive ▁feature ▁is ▁its ▁cher ry - like ▁b ark , ▁with ▁horizontal ▁stri pes ▁of ▁re dd ish - gre y ▁becoming ▁dark ▁grey ▁with ▁age , ▁ex fol i ating ▁in ▁thin ▁pap ery ▁curl s . ▁The ▁dark ▁green ▁leaves ▁are ▁up ▁to ▁ 1 0   cm ▁long ▁and ▁turn ▁golden - yellow ▁in ▁aut umn . ▁The ▁sho ots ▁are ▁a rom atic , ▁and ▁carry ▁long , ▁yellow - b rown , ▁male ▁cat kins ▁in ▁early ▁spring . ▁. ▁The ▁species ▁is ▁considered ▁closely ▁related ▁to ▁the ▁American ▁bir ch ▁Bet ula ▁l enta . ▁Hard iness : ▁R HS ▁H 4 . ▁ ▁References ▁ ▁Category : Fl ora ▁of ▁Japan ▁gross a ▁Category : T ax a ▁named ▁by ▁Joseph ▁Ger hard ▁Zu cc ar ini <0x0A> </s> ▁Bo om ▁usually ▁refers ▁to ▁an ▁on om at op oe ic ▁word ▁for ▁the ▁sound ▁that ▁an ▁explos ion ▁makes . ▁Bo om ▁may ▁also ▁refer ▁to : ▁ ▁Object s ▁ ▁Bo om ▁( cont ain ment ), ▁a ▁temporary ▁floating ▁bar rier ▁used ▁to ▁contain ▁an ▁oil ▁sp ill ▁ ▁Bo om ▁( n avig ational ▁bar rier ), ▁an ▁obst acle ▁str