Lub paj no yog hu ua ib tug hloov tsob nroj tua, npaj rau yug me nyuam noob. Tsis zoo li qub ceg (tua), nws muaj los ntawm ib tug paj cos. Qia ntawm lub paj yog pedicel thiab receptacle. Corolla, calyx, Stamens thiab pistils hloov nplooj raug tsim. Yuav kom to taub yog vim li cas peb yuav tsum tau cov nroj tsuag tag nrho cov lub cev yuav tsum xav txog nyob rau hauv ntau yam cov qauv ntawm txhua lub paj. Yog li ntawd, nyob rau hauv nws qhov chaw yog lub pistil, uas, txawm nws lub npe, yog ib tug "poj niam" deev hloov. Feem ntau, nyob ib ncig ntawm nws yog heev heev Stamen, uas yog "txiv neej" deev hloov. Nyob rau hauv txhua lub paj Stamen thiab pistil - qhov tseem ceeb ntawm nws. Ntawm lawv nws yuav tom qab yuav tsim nyob rau txiv hmab txiv ntoo ntawm ib tsob nroj uas nws cov noob yog ib tug txhim khu kev qha txhais tau tias ntawm tu tub tu kiv.
Stamen thiab pistil ua si ib qho tseem ceeb heev luag hauj lwm nyob rau hauv lub neej ntawm flowering nroj tsuag. Cov txiv neej sib deev hloov khoom nruab nrog ntawm tej yam ntawm lub paj, nws yog ib lub sau los ntawm tag nrho cov Stamens, hu ua "androecium". Txhua yam ntawm lawv muaj ib tug "Staminate xov" thiab 4 "lub paj ntoos sac," neeg raug kaw "tuaj". Nws muaj ob halves, txhua tus uas, nyob rau hauv lem, muaj ob kab noj hniav (lag los yog nyob). Lawv tsim tag nrho cov paub cov paj ntoos. Raws li staminal filaments tuav dej thiab as-ham. Poj niam deev hloov khoom nruab nrog ntawm ib lub paj yog "gynoecium", uas, nyob rau hauv qhov tseeb, hu ua "qws txob". Nws muaj ib tug "kem," "zes qe menyuam" thiab "stigma". Nyob rau qhov no "stigma" thiab tau mus siav paj ntoos rau lub Stamens. "Kem" ua kev pab txhawb nqa zog, thiab ntawm lub "zes qe menyuam", muaj ovules (ib los yog ntau tshaj) loj hlob lub noob ntawm fertilization. Lub ovules yog embryo hnab, uas yog tsim sai heev thiab daim ntawv txiv hmab txiv ntoo nroj tsuag. Pistil thiab Stamen, lub tswvyim uas yuav tsis tau ua kom tiav tsis muaj tus "nectary", emitting ib tug qab zib paj ntoo, feem ntau tau txais paj ntoos ntawm kab, flitting los ntawm paj mus rau paj. Perianth muaj ib tug Corolla thiab calyx. Pistil thiab Stamen surrounded perianth.
Muaj ntau ntau txawv hom ntawm paj, uas yog tshwm sim los ntawm lub xub ntiag ntawm cov neeg los yog lwm yam kabmob. Yog li, cov nroj tsuag nyob rau hauv uas lub paj muaj ib tug pistil thiab Stamens, yog "bisexual". Yog hais tias muaj yog tsuas Stamens los yog pistils xwb - cov nroj tsuag yog hu ua "dioecious". "Monoecious" xa mus rau cov neeg ntawm tus muaj, uas yog kawm los ntawm cov paj thiab cov Stamens, thiab pistils nrog. "Dioecious" cov nroj tsuag yog hu ua, muaj tsuas pistillate los yog staminate paj xwb.
Tus qauv ntawm lub pistil thiab Stamens tsim lab xyoo. Lub paj yog lub deev hloov ntawm angiosperms. Stamen thiab pistil muab cog tsim txiv hmab txiv ntoo (cov noob). Cov txiv hmab txiv ntoo zoo nkaus li nyob rau hauv tus txheej txheem ntawm fusion ntawm carpel. Nws yog ib tug yooj yim (taum mog, plums, txiv ntoo qab zib) los yog complex (muaj ob peb fused pistils - lub paj, Lily, cornflower). Cov mej zeej coob ntawm tus muaj yog undeveloped (rudimentary) pistils. Hom ntau haiv nyob rau hauv lub cov ntaub ntawv thiab cov qauv ntawm cov paj vim lub tsob nyob rau hauv lub chav kawm ntawm ib tug ntev evolution ntawm txawv nyob rau hauv lawv txoj kev pollination.