ポインセチアはトウダイクサ科トウダイクサ属の園芸品種。和名はショウジョウボク(猩々木)というが、使われず、もっぱらポインセチアと呼ばれ、クリスマスの頃に売り出されるため、クリスマスフラワーともいわれる。苞が真っ赤にになるのが特徴。最近では多くの品種が作り出され、苞も色とりどりである。
　低木～小高木、高さ1～3(～4) m、多数、分枝する。茎は無毛。葉は互生。托葉は小さく、膜質、脱落性。葉柄は長さ2～5㎝、無毛。葉身は卵状楕円形～長楕円形～披針形、しばしば浅く分裂し、長さ6～25㎝×幅4～10㎝、下面は有毛、上面は短毛があるか又は無毛、基部は漸尖し、先は尖鋭形又は鋭形。杯状花序はごく密集してつき、片側だけの合成花序、5～7個の柄のある葉状の苞が基部につく。苞は狭い楕円形、長さ3～7㎝×幅1～2㎝、普通、全縁、ときに、さざ波状に分裂し、深紅色。花序柄は長さ3～4㎜。総苞はつぼ形、薄緑色、長さ7～9㎜×幅6～8㎜。裂片は5個、引き裂かれ、三角形、無毛。腺体は普通1個、まれに2個、黄色、平らに圧搾され、2唇があり、長さ4～5㎜×幅約3㎜。雄花は多数、普通、総苞から突き出す。苞は線形、軟毛がある。雌花は子房が無毛、柄があり、総苞から突き出し、平滑。花柱は中間より下で合着する。柱頭は深く2裂。蒴果は3裂の球形、長さ1.5～2㎝×幅約1.5㎝、平滑で無毛。種子は卵形、約長さ10㎜×幅8～9㎜、灰色又は薄灰色、ほぼ平滑、カルンクルは無い。花期と果期は10～4月。
品種)　'13869' (PBR) , 'Adventsstern von Werder' , Airbrush' , 'Alreddy Red' (PBR) , 'Amazone' , 'Angelika' , Apricot Highlight = 'Duestarapri' , 'Autumn Leaves' , Autumn Red , 'Bella Italian Red', 'Bellstar' , 'Bkponch' (PBR), 'Bkponhl' (PBR) , Bkpontw' (PBR) , 'Blizzard' , 'Bonpoiakaichi' , 'Bonpri 2761' (PBR) , Bonpri 635' (PBR) , 'Bonpridepcom' (PBR) , 'Bonprilipcom' (PBR) , 'Br52' D, Brave Bright Red = 'Duebravo' (PBR) , 'Bright Marble Queen' , 'Bright Red Queen' , Bright Red Sails = 'Eckadonis' , 'Bright White Princess' , 'Carousel' , 'Carousel Dark Red' (PBR) , 'Castor Red' (PBR) , 'Champion Fire', 'Champion Hot Pink' , 'Champion Red' , 'Chianti Red' , Christmas Feelings Fantasy , Christmas Feelings Flamingo , Christmas Feelings Glitter , Christmas Feelings Pink = 'Npcw04081' , Christmas Feelings Red = 'Npcw02044' (PBR) , 'Cortez' , Cortez Burgundy = 'Kamp Burgundy' (PBR) , Cortez Electric Fire = 'Fiscor Electric' (PBR) , Cortez Fire = 'Fiscor Fire' (PBR), Cortez Marble = 'Fiscor Marble' , Cranberry Punch = 'Eckabish' (PBR) , 'Darlyne' , 'Diva Starlight' , 'Dorothee' ,'Dr. Yoshoi's White', 'Ducapink' , 'Dueamahopi' (PBR), 'Dueamalipi' (PBR) , 'Duearcwi' (PBR) , 'Dueavant', 'Per1904' , 'Dueavant', 'Dueavared', 'Duebired' , 'Duebravo' (PBR) , 'Duecabrired' , 'Duecap' (PBR) , 'Duecapmar' , Duecapwi', 'Duechamp' (PBR) , Duechampfi' (PBR) , 'Duechampho' (PBR) , 'Duechampwhi' (PBR) , 'Duechampwhi' (PBR) , 'Duecohopi' ,'Duelent' , 'Duecomar' , 'Duecopink' (PBR) , 'Duecored' (PBR) , 'Duecosmo' (PBR) , 'Duecowhite' (PBR) , 'Dueday' , 'Duedeluxe', 'Dueearlyglory' (PBR) , 'Dueedli' (PBR) , 'Dueeublabeau' , 'Dueflame' (PBR) , 'Dueflashred' , 'Duegla13' (PBR) , 'Dueglaearl' (PBR) , 'Duehidared' , 'Duehigh' , 'Duehiora' , 'Dueholjol' , 'Dueimco' , 'Dueimviking' (PBR) , 'Dueinfifire' , 'Dueinfinity' (PBR) , 'Dueinfinitybri' , 'Dueinfinityma' (PBR), 'Dueinfinitywi' (PBR) , Duelebri' , 'Duelepink' , 'Duelewi' (PBR) , 'Duelimelight' , 'Duelimelight' , 'Duemal' , 'Duemalbri' , 'Duemalmar' , 'Duemalrose' , 'Duemalwi' , 'Duematin' (PBR) , 'Duemenor' , 'Duemenorca' , 'Duemerlot' (PBR) , 'Duemetro' , 'Duemirage' , 'Duemond' , 'Duemondfi' , 'Duemoon' , 'Duenidared' (PBR) , 'Dueouvert' (PBR) , 'Duepre' (PBR) , 'Duepremearl' (PBR) , 'Duepremice' (PBR ), 'Duepremice' (PBR) , 'Duepremimapri' (PBR) , 'Duepremimhopi' , 'Duepremimpol' (PBR) , 'Duepremmar' (PBR) , 'Duepremmiro', 'Dueprempica' , 'Dueprempink' (PBR) , 'Duepremwi' (PBR) , 'Dueprew112' (PBR) , 'Dueprima' (PBR) , Dueprimdon' (PBR) , 'Dueprimver' (PBR) , 'Dueprimver' (PBR) , 'Dueprotege' (PBR) , 'Dueredwi' (PBR) , 'Dueroyal' , 'Duescandic' (PBR) , 'Duescanearl' (PBR), 'Duescanpi' (PBR) , 'Duespot' (PBR) , 'Duespotapri' , 'Duespotpink', 'Duespotwit' , 'Duespotwo' , 'Duestar' , 'Duestarapri' , 'Duestared' , 'Duesup12' (PBR) , 'Duesupreme' (PBR) , Dueternity' , 'Duetwister' , 'Dueurostar' (PBR 'Duevikicin' (PBR) , 'Duewi' , 'Duexcel' , 'Duexen' , 'Duextreme' , 'Early Joy' , 'Eckab' , 'Eckabbo' , 'Eckabdul' , 'Eckabia' , Eckabiel' 'Eckabish' (PBR) , 'Eckabner' , 'Eckabri' , 'Eckabud' (PBR) , 'Eckace' , 'Eckacton' , 'Eckada' , 'Eckadali' , 'Eckadama' , 'Eckaddis', 'Eckadela' , 'Eckadin' , 'Eckadire' , 'Eckadney' (PBR) , 'Eckadolfo' , 'Eckadria' , 'Eckadrian' , 'Eckadrian' , 'Eckaggie' , 'Eckahab' (PBR) , 'Eckahmed', 'Eckaiden', 'Eckaileen' , 'Eckaimon' , 'Eckajala' , 'Eckakeem' (PBR), 'Eckalba' , 'Eckalbinka' (PBR) , 'Eckaleeza' , 'Eckalger' (PBR) , 'Eckalix' , 'Eckaloha' , 'Eckalon' (PBR) , 'Eckalveen' (PBR) , 'Eckalverta' (PBR) , 'Eckanezka' (PBR) , 'Eckansley', 'Eckaykin' , 'Ecke 710' (PBR) , 'Ecke Arforonebe' (PBR), 'Ecke Red' , ' 'Ecke Sevforfiv' (PBR) , 'Ecke Sevotwo' , 'Ecke White' , 'Ecksnow' , 'Eclipse Red', Eda Pan 1' , ' Eda Rose' , ' 'Enduring Pink' , 'Enduring Red' , 'Enduring White' , 'Estrella Pink' (PBR), 'Estrella Red' (PBR) , 'Femina' , 'Firework' , 'Fisbla' , 'Fiscinne' , 'Fiscor' , Fiscor Dark Red' , 'Fiscor Electric' (PBR) , 'Fiscor Fire' (PBR) , 'Fiscor Hot Pink' , 'Fiscor Jingle' , Fiscor Marble' , 'Fiscorosa' , 'Fisearltez' (PBR), 'Fiselfi' , 'Fisflirt' (PBR) , 'Fisflirt Silver' , 'Fisgala' (PBR) , 'Fisholly' , 'Fislemon' , 'Fismarble Silver' , 'Fismars' (PBR) , 'Fismars 339' (PBR) , 'Fismars Creme' , 'Fismars Marble' (PBR) , 'Fismars Pink' , 'Fismille' (PBR) , 'Fismired' (PBR) , 'Fismired' , 'Fismirpink' (PBR) , 'Fismirwhi' (PBR) , 'Fismond', 'Fisnova' , 'Fisnovired' (PBR) , 'Fisolymp' (PBR) , 'Fispic' , 'Fispoin 1-1' , 'Fispue' , 'Fispue Silver' , 'Fispue White' (PBR) , 'Fissilver' , 'Fisson' , 'Fisson Beckpink', 'Fisson Cream' (PBR) , 'Fisson Dark Red' , 'Fisson Hot Pink' , 'Fisson Jingle' , 'Fisson Jinglit' , 'Fisson Marble' , 'Fisson Orange' , 'Fisson Pink' (PBR) , 'Fisson Piz' , 'Fisson Salmon' , 'Fisson White' (PBR) , 'Fissonosa' , 'Fisvinci' , ' 'Floasatur' (PBR) , 'Floristella Red' , 'Formentera' , 'Freedom' (PBR) , 'Freedom Bright Red' (PBR) , Freedom Coral , Freedom Fireworks , 'Freedom Jingle Bells' , 'Freedom Marble' , Freedom Rose = 'Eckadama' , Freedom Salmon = 'Eckadrian' , Freedon Orange = 'Eckacto 'Future Pink' , 'Gala Red' , Goldfinger Pink' , 'Heidi' , Heirloom Pink = 'Silverleaf' , Heirloom Red = 'Eda Pan 1' , Heiroom Peach = 'Eckadolfo' , Holly Point = 'Eckansley' , 'Ice Punch' (PBR), 'Ice Punch' , 'Impromptu' , 'Infinity Marble' , 'Infinity Polar' , 'Infinity Red' , 'Jacabia' (PBR) , 'Jacabre' , 'Jacadame' , 'Jacaimee' , 'Jacamed' , Jester Jingle = 'Eckadria' , Jester Red = 'Eckalverta' (PBR) , 'Kamp Burgundy' (PBR) , 'Klepocar' , 'Klepocri' (PBR), 'Kleposan', 'Kleposapi' , 'Klepove' , 'Klew01064' , 'Klew01065' , 'Klew01066' , 'Klew01071' , 'Fisbon' , 'Klew01072' , 'Klew01073' , 'Lazzpo1023' , 'Lazzpo1047' (PBR) , 'Lazzpoapa' , 'Lazzporb' , 'Lazzporccc' (PBR 'Lazzpored' (PBR) , 'Lazzporeff' (PBR) , 'Lazzporega' (PBR) , 'Lazzporei' (PBR), 'Lazzporejes' (PBR) , 'Lazzporsa' , 'Lazzporsbo' , 'Lazzpowhite' (PBR), 'Lazzpoyea' (PBR) , 'Lemon Drop' , Lemon Snow = 'Fislemon' , 'Liberty Marble', 'Liberty Pink' , 'Liberty Red', 'Liberty Snowflake' (PBR) , 'Lilo Pink' , 'Lilo Red' , 'Lilo White', Luv U Pink = 'Perhc59b' , 'Mallorca' , 'Marbella' , 'Marble Peterstar' , 'Marblestar' (PBR) , 'Maren' (PBR) , 'Maroflame', Mars Pink , Mars White (PBR) , Max Red = 'Eckadin', 'Menorca' , Millenium = 'Fismille' (PBR) , Mira Pink = 'Fismirpink' (PBR), 'Monet' , 'Moni' , 'Nobelstar' , Nova = 'Fisnova' , 'Npcw02022' (PBR), 'Npcw02042' (PBR) , 'Npcw02044' (PBR) , 'Npcw04081' , 'Npcw04095' (PBR) , 'Npcw04097' , 'Npcw04107' (PBR) , 'Npcw05093 'Npcw05102', 'Npcw06115' (PBR) , 'Npcw07120' (PBR) , 'Npcw08119' (PBR), 'Npcw08153' (PBR) , Npcw09124' (PBR) , 'Npcw10158' (PBR) , 'Npcw10164' (PBR) , 'Npcw10167' (PBR) , 'Npcw10171' (PBR) , 'Npcw10184' , 'Npcw10187' (PBR) , 'Npcw10193' , 'Npcw11201' (PBR), 'Npcw12198' (PBR) , 'Npcw12200' (PBR) , 'Npcw13211' (PBR) , 'Npcw13218' (PBR) , 'Oglpnt14001' , 'Oglpnt14001' , 'Orange Red Lilo' , 'Peace Jolly Red' , 'Pecool' , 'Pefreseed' , 'Pegirl' , 'Lilo' , 'Pemunone' , 'Pepliloerl' , 'Pepmondk' , 'Peppar', 'Pepride' (PBR) , Pepride Jingle Bells = 'Eckahmed' , Pepride Marble = 'Eckaiden' , Pepride Pink = 'Eckabri' , Pepride White = 'Jacaimee' , 'Pepteen' , 'Per101' (PBR) , 'Per1072' (PBR 'Per1090' (PBR) , 'Per1120' (PBR) , 'Per1139' (PBR) , 'Per11403' (PBR) , 'Per1180' , 'Per1188' (PBR) , 'Per1230' (PBR) , 'Per1270' (PBR) , 'Per1902' (PBR) , 'Per1904' , 'Per2009' (PBR) , 'Per2204', 'Per2804' , 'Per2904' , 'Per3811' (PBR), 'Per4703' , 'Per6502' , 'Per7102' (PBR) , 'Per8603' , 'Per964' (PBR) , 'Pestartetra' (PBR) , 'Peterstar' (PBR) , Peterstar Orange = 'Sole Mio' , 'Petoy' , 'Picasso' , 'Pink Cadillac' , 'Pink Freedom' (PBR) , 'Pink Peppermint' , 'Pink Peterstar', 'Pick Me Pink'(Poinsettia hybrid) , Pink Splendor = 'Eckabiel' , 'Pink Steffi' , Premium Ice Crystal = 'Duepremice' (PBR) , Premium Lipstick Pink = 'Dueprempink' (PBR) , 'Premium Marble', Premium Polar = 'Duepremimpol' (PBR) , Premium Red = 'Duepre' (PBR) , Prestige = 'Eckadire' , 'Primero White' , Princettia Dark Pink = Princettia Hot Pink = 'Bonpripicom' (PBR) , Princettia Pearl = 'Bonpri635' (Princettia Series) , Princettia Pink = 'Bonprilipcom' (PBR), Protege Dark Red = 'Dueprotege' (PBR) , 'Purple Heart' , 'Purple Rain' , Purple Reign = 'Renate' , 'Queen of Orange' , 'Red Angel' (PBR) , 'Red Baron', 'Red Dragon' , Red Elf = 'Fiselfi' , 'PERHC59B' , 'Red Fox Spotlight Pink' , 'Red Fox Spotlight Red' , 'Red Fox Spotlight White' , 'Red Sails', Red Satin = 'Eckabia' , 'Red Splendor' , Red Velvet = 'Eckada' ., 'Regina' , 'Renate', 'Rfpdpc1' (PBR) , 'Rfphpg1' (PBR) , 'Rfppcc1' (PBR) , 'Rfppg1' (PBR) , 'Ria' , 'Salmonstar' , 'Scandic Early' , 'Scandic Hot Pink' , Silver Bells = 'Eckabdul' , 'Silverleaf' , Silverstar = 'Fissilver', Silverstar Marble = 'Fismarble Silver' , Silverstar Pink = 'Fisflirt Silver' , 'Silverstar Red', Silverstar White = 'Fispue Silver' , 'Sole Mio' , Sonora Dark Red = 'Fisson Dark Red' , Sonora Fire = 'Fisson Orange' , Sonora Hot Pink = 'Fispoin 1-1' , Sonora Jingle = 'Fisson Jingle' , Sonora Marble = 'Fisson Marble' , Sonora Pink = 'Fisson Pink' (PBR), Sonora Pink = 'Fissonosa' , Sonora Red Glitter, Sonora Salmon = 'Fisson Dark Red' , Sonora White = 'Fisson White' (PBR) , Sonora White Glitter = 'Fisson Jinglit' , 'Sophie' , 'Spotlight Apricot' , 'Spotlight Red' , 'Spotlight Victory Red' , 'Spotlight White' , 'Stargazer' , 'Stargazer Red' , 'Stargazer White' , 'Steffi' , Strawberries and Cream = 'Eckaloha' , Strawberry Punch = 'Eckaleeza' , 'Success' , Success Coral = 'Eckabsal' , Success Light Pink = 'Eckaggie' , Success Pink = 'Eckabner' , 'Sunora' , 'Sunora White' , 'Supjibi' , 'Syep 22432' (PBR) , 'Syep0791' (PBR) , 'Syep22866' (PBR) , 'Syep23203' (PBR) , 'T13' , 'Temptation Red', 'Tendresse' (PBR) , Titan Red = 'Syep 22432' (PBR) , 'Top White' , 'Velocity' , Viking Cinnamon = 'Duevikicin' (PBR) , 'Vinterstar' , 'White Freedom' (PBR) , 'White Peterstar' , White Splendor = 'Eckadali' , Whitestar , 'White Steffi', 'Windark' , 'Winpeach' (PBR) , 'Winred' (PBR) , ' 'Winter Rose' , Winter Rose Chiffon Pink = 'Winpeach' (PBR) , Winter Rose Cream = 'Eckaimon' , Winter Rose Crimson Red = 'Winred' (PBR) , Winter Rose Jingle Bells = 'Eckaileen' , Winter Rose Pink = 'Eckaddis' , 'Winter Rose Red' , Winter Rose White = 'Winwhite' , 'Winterfest Red' (PBR) , 'Winwhite'