Gymnosperms

Gymnosperms gano su tarihi daga lokacin paleofita. Yana da ga cikin tsohon tarihin da shuka ne halin da tartsatsi spore. Sun kasance sũ ne babban wakilan da Flora. Late Permian lokaci Flora kawo manyan canje-canje: domin maye gurbin zamanin da kwal swamps tare da su Flora zo lokaci mabanbanta shuke-shuke. Gymnosperms musamman shahara, da kuma zauna manyan mukamai a lokacin da Mesozoic.

Ana zargin wannan rukuni na shuke-shuke da aka mai m mataki a cikin tsarin juyin halitta. Preexisting Fern a kiwo aiwatar da ruwa-ruwa matsakaici ake bukata. Shawarwari, da samun fita daga cikin sporangium a cikin m ƙasa, kwalfar prothallia tare da jima'i gabobin. Idan shuka ne a ci gaba da daban-daban siffofin spores, wasu daga cikinsu suna tasowa biyu prothallia: daya mace da sauran tare da namiji gabobin. Bugu da ari, kan aiwatar da hadi faruwa, archegonium - mace jima'i cell - shi ne ya gama da namiji jima'i cell, a cikin wannan harka a wannan alamomin ne samuwan ruwa. Yana daidai wannan shawara ne da cewa da pre-data kasance ferns da psilophytes samo asali daga ruwa shuke-shuke. Wannan guda fasalin muhimmanci iyakance rarraba shuke-shuke - ciyayi iya kawai faruwa a wuraren da high zafi.

A sabon rukunin ma rasa dogara a kan gaban ko babu ruwa. A haifuwa na gymnosperms shuke-shuke ne kamar haka: iska ta fãɗa da hirtsinta da iri ci gaba faruwa dama a kan masu juna biyu kwafin. Amma wannan ba kawai amfani da wannan kungiya. Idan shawarwari ne kawai 1 cell, wanda yana da iyaka wadata da na gina jiki, sa'an nan da iri na ilimi riga kwayar, tabbatar da wadata na abubuwa da muhimmanci a lokacin da amfrayo ci gaba. Bugu da ƙari, kasancewar Sikeli iri tayi ne na halitta dogara da kariya daga muhalli hadura. Wadannan sabon fasali na tsarin sun kasance muhimmanci ga juyin halitta daga cikin Flora. gymnosperms samu ingantattun yanayi na kiwo da kuma kiyayewa.

Yau wadannan tsire-tsire ne fitaccen malamai a raba aji. Kuma dukan tarihin su ci gaba ya tabbatar da cewa shi ya faru angiosperms daga gymnosperms. All membobin wannan kungiya (gymnosperms) zuwa kashi hudu sassan: ginkgovidnye, gnetophyta, cycad, conifers.

Abin da unites wannan kungiya? Mene ne alamun gymnosperms? Dukansu suna da shrubs ko itatuwa, sau da yawa na babban size. Wasu, silnovetvyaschiesya, bambanta da babban yawan kananan ganye (iya zama scaly). Wasu, duk da haka, dan kadan branched, amma tare da babbar feathery ganye. Xylem ba tare da tasoshi, da phloem abõkinsa cell-free - wani hali na kowa zuwa mafi gymnosperms. Su heterosporous. A siffar, size da kuma tsarin da micro- da makrosporofill sosai daban-daban. Free girma a kan wani al'ada gudun hijira - daga wani m iri fern a kan strobilae (short harbe) - wani gymnosperms.

Hirtsinta pores ko hancin gurtsun dabino daga turɓãya - shi microspores, wurin da - pollen jakar kwai. Shi ne su iska ta fãɗa da mace gametophyte. A ovule ne da ake ci gaba riga megaspory. A hadi da namiji gamete ovule zama da iri. A rarrabe da mace gametophyte - jure dehydration. The iri ne kewaye da wani sinadarin gina jiki ajiye, wanda yana amfani da wani zygote a kan aiwatar da germination, amma kafin farko na sharadi gwargwado ga iri zauna a cikin m jihar. Fruit ba kafa, amma iri ne iya tasowa da dama na'urorin.