First ovules integument:what roles?  

作　　者：Brigitte Meyer-Berthaud 

机构地区：[1]AMAP,Universit´e de Montpellier,CNRS,CIRAD,INRAE,IRD,France

出　　处：《National Science Review》2022年第4期16-17,共2页国家科学评论（英文版）

摘　　要：The Famennian is a period of increased taxonomic diversity for the first representatives of the major plant groups,especially the spermatophytes(i.e.the seed plants)that,today,represent the most abundant and diversified plant group on Earth[1,2].Early spermatophytes evolved a unique ovule-centered reproductive syndrome that allowed them to germinate and grow rapidly in disturbed habitats and,secondarily,to colonize dry habitats unfavorable to the reproduction of their free-sporing predecessors[3,4](Fig.1).In these ovulate organisms,the female gametophyte grows and produces gametes inside the indehiscent megasporangium(nucellus)that differentiates a pollen chamber retaining the pollen grains in its apical part.An integument encloses the nucellus.Like the Runcaria protovule that preceded them by 20 million years,Famennian ovules were all surrounded by a cupule,except perhaps Spermolithus and Warsteinia[5-7].

关 键 词：HABITAT retaining abundant 

分 类 号：Q941.2[生物学—植物学]