大王花(hua)(hua)是(shi)(shi)一種肉(rou)質寄生草本植物(wu)而(er)(er)并非真的“食人(ren)花(hua)(hua)”。它(ta)們主軸極短(duan),沒有(you)葉片和(he)地(di)下莖(jing),吸取營養的器官退化成菌絲體狀(zhuang),侵入宿(su)主的組織(zhi)內,因此整朵(duo)花(hua)(hua)就是(shi)(shi)它(ta)的全部。從(cong)宿(su)主身上(shang)吸收的營養幾乎(hu)全部供應花(hua)(hua)朵(duo)的生長,花(hua)(hua)徑(jing)能夠達到0.9144米(mi)(mi),最(zui)高紀(ji)錄可(ke)達1.4米(mi)(mi)。大王花(hua)(hua)的基座是(shi)(shi)由宿(su)主的木質部發(fa)展而(er)(er)來(lai)的,形(xing)狀(zhuang)很(hen)象個廣口壇子。
肉質、寄(ji)生(sheng)(sheng)草本,寄(ji)生(sheng)(sheng)于植物的(de)根、莖或(huo)(huo)枝條(tiao)上(shang),無(wu)(wu)葉(xie)綠(lv)素;葉(xie)退(tui)化成(cheng)(cheng)鱗片或(huo)(huo)無(wu)(wu)。花(hua)通常(chang)單生(sheng)(sheng),輻射(she)對稱,單性(xing),雌(ci)(ci)雄(xiong)(xiong)異株,兩性(xing),十分巨大(世(shi)界(jie)上(shang)最大的(de)花(hua):大花(hua)草亦稱阿諾德大王花(hua)(Rafflesia arnoldii R.Br.)直徑約1米,重達(da)7.5千克,產蘇門答臘。),花(hua)被(bei)(bei)合生(sheng)(sheng),裂片4-10或(huo)(huo)無(wu)(wu),稀分離;雄(xiong)(xiong)花(hua):雄(xiong)(xiong)蕊多數(shu)至(zhi)5枚,無(wu)(wu)花(hua)絲(si),1-3列環生(sheng)(sheng)于蕊柱上(shang),或(huo)(huo)在兩性(xing)花(hua)中合生(sheng)(sheng)成(cheng)(cheng)筒狀(zhuang),花(hua)藥2室(shi),縱裂或(huo)(huo)頂孔開(kai)裂,藥室(shi)有(you)時匯(hui)合,花(hua)粉常(chang)具粘性(xing),單個或(huo)(huo)成(cheng)(cheng)四分體;雌(ci)(ci)花(hua):雌(ci)(ci)蕊由8-6-4枚合生(sheng)(sheng)心皮(pi)所組(zu)成(cheng)(cheng),子房下位、半下位或(huo)(huo)上(shang)位,1室(shi)或(huo)(huo)胎(tai)(tai)座突伸于近中部形成(cheng)(cheng)許多不規則的(de)腔隙;胚(pei)珠極多數(shu),生(sheng)(sheng)于側膜胎(tai)(tai)座上(shang),珠被(bei)(bei)1-2層;花(hua)柱1或(huo)(huo)無(wu)(wu),柱頭盤狀(zhuang)、頭狀(zhuang)或(huo)(huo)多裂。果為漿果;種子小(xiao),種皮(pi)堅硬(ying),有(you)內(nei)胚(pei)乳(ru)。