Gymnosperms

Gymnosperms ukulandelela umlando wabo kusukela esikhathini paleofita. Kungenxa umlando simila lasendulo libhekene spore okwandile. Yibona abameleli eyinhloko izitshalo. Late Permian isikhathi flora kuletha izinguquko ezinkulu: ukufaka esikhundleni kwenkathi kwamalahle emaxhaphozini izimbali zabo kufika isikhathi ngokuphelele izitshalo ezahlukene. Gymnosperms ikakhulukazi iyachuma futhi abanezikhundla okuholela inkathi Mesozoic.

Ukuvela leli qembu izitshalo kwaba igxathu lesichubekako inqubo yokuziphendukela kwemvelo. olwase lukhona Fern e inqubo ukubuyabuyelela naphakathi aqueous edingekayo. Ingxabano, waphuma sporangium enhlabathini olumanzi, ziqhume prothallia nge kwezitho zobulili. Uma isitshalo ungaphakathi ukuthuthukiswa ezahlukene amafomu ezinhlamvu, ezinye zazo bayatfutfuka prothallia ezimbili: elilodwa lensikazi nabanye nge izitho besilisa. Ngaphezu kwalokho, inqubo sokukhulelwa kwenzeka kanjalo, archegonium - zesifazane ubulili iseli - ukuxhuma iduna ubulili cell, kuleli cala imfuneko kuyinto ukutholakala kwamanzi. Kuyatjho bona agumenti Kuyaphawuleka ukuthi Izinhlobo pre-ekhona futhi psilophytes savela ezimila emanzini. Lesi sici efanayo kakhulu kungagcini ukusatshalaliswa izitshalo - izimila ubengase zenzeka ezindaweni nge umswakama high.

Iqembu elisha futhi walahlekelwa ukuncika khona noma ukungabi khona amanzi. A kabusha gymnosperms izitshalo simiswe ngalendlela lelandzelako: umoya idlulisa impova imbewu ukuthuthukiswa kwenzekani kwesokudla ikhophi kwabakhulelwe. Kodwa lokhu akulona inzuzo kuphela leli qembu. Uma ingxabano 1 cell kuphela, okuyinto okukhawulelwe kwezakhi ke imbewu lemfundo ezinamangqamuzana amaningi kakade, waqinisekisa supply izinto ezibalulekile ngesikhathi ukuthuthukiswa sombungu. Ngaphezu kwalokho, ukuba khona izikali imbewu umbungu kuyinto engokwemvelo isivikelo kusuka ezikwimvelo. Lezi zici entsha isakhiwo bebelokhu kubalulekile ukuvela flora; gymnosperms ukuthola izimo ezithuthukisiwe for zizalela kanye nokulondolozwa.

Namuhla lezi zitshalo izazi ovelele e esihlukile. Futhi wonke umlando ukuthuthukiswa kwabo kubonakala ukuthi kwenzeka angiosperms kusukela gymnosperms. Zonke amalungu aleli qembu (gymnosperms) ngezigaba ezine: ginkgovidnye, gnetophyta, cycad, AmaConifers.

What esihlanganisa leli qembu? Yiziphi izimpawu gymnosperms? Bonke bangabangasokile nezihlahla noma izihlahla, ngokuvamile esikhulukazi. Abanye, silnovetvyaschiesya, zihlukaniswa inqwaba amahlamvu ezincane (kungenzeka zibe maholoholo). Nokho, abanye kancane branched, kodwa namahlamvu omkhulu feathery. Xylem ngaphandle izitsha, kanye nomngane phloem cell-mahhala - omunye umkhuba ovamile gymnosperms kakhulu. Ziyakwazi heterosporous. Ukuma, ubungako kanye nesakhiwo micro- futhi makrosporofill ezahlukene kakhulu. ukukhula Mahhala ku Ukuphunyuka ezivamile - kusuka bakudala imbewu Fern ku strobilae (amahlumela iDemo) - yimuphi omunye gymnosperms.

Impova ikhule ezimbotsheni noma uma liqhathaniswa nendawo ngothuli - ke microspores, kule ndawo - impova sac. Kuyinto umoya wabo idlulisa gametophyte zesifazane. I ovule isakhiwa megaspory kakade. Ngesikhathi sokukhulelwa iduna gamete ovule iba imbewu. Isici esiphawulekayo gametophyte zesifazane - ukumelana ukuphelelwa amanzi emzimbeni. Imbewu lizungezwe inqolobane izakhi, olusebenzisa zygote e inqubo ukuhluma, kodwa ngaphambi ukuqala isimo imbewu uhlala isimo ethule. Izithelo is ayakhekanga, kodwa imbewu uyakwazi ukuthuthukisa ezihlukahlukene amadivaysi.