Oak Spring Garden Foundation, Upperville, VA, 20184, USA.
Yale School of the Environment, Yale University, New Haven, CT, 06511, USA.
New Phytol. 2024 Dec;244(5):2089-2100. doi: 10.1111/nph.20132. Epub 2024 Sep 20.
Recent paleobotanical discoveries have renewed interest in the distinctively recurved, seed-bearing cupules of Mesozoic plants, which are important for understanding seed plant phylogeny and the origin of the second integument of the angiosperm ovule. Reanalysis of the enigmatic seed-bearing organ Dordrechtites elongatus from the Triassic of South Africa, the type species of the genus, combined with information from similar material from Antarctica, Argentina and Australia, indicates that Dordrechtites is a highly modified lateral branch of a seed cone. Short lateral projections from a primary cone axis each bear several Dordrechtites units. Each unit consists of a long stalk bearing a straight to sometimes recurved cupule with a long distal extension beyond the cupule apex. Each cupule is flattened in a plane perpendicular to the stalk and distal projection and contains up to two seeds. Structural similarities between Dordrechtites and the cupules of Doyleales indicate that they are homologous, providing new evidence for a close relationship. The persistent cupule stalk and apical extension of Dordrechtites, combined with the flattened cupule, suggests modification for wind and water dispersal.
最近的古植物学发现重新引起了人们对中生代植物特有的弯曲、具种子的杯状结构的兴趣,这些结构对于理解种子植物系统发育和被子植物胚珠第二珠被的起源非常重要。对来自南非三叠纪的神秘种子器官 Dordrechtites elongatus 的重新分析,该属的模式种,结合来自南极洲、阿根廷和澳大利亚的类似材料的信息,表明 Dordrechtites 是种子锥体的高度修饰的侧枝。来自主锥体轴的短侧突每个都带有几个 Dordrechtites 单元。每个单元由一个长柄组成,柄上带有一个直的或有时弯曲的杯状结构,其远端延伸超出杯状结构的顶点。每个杯状结构在垂直于柄和远端突起的平面上变平,并且包含多达两个种子。Dordrechtites 和 Doyleales 的杯状结构之间的结构相似性表明它们是同源的,为密切的亲缘关系提供了新的证据。Dordrechtites 的持久的杯状结构柄和顶端延伸,以及扁平的杯状结构,表明其为风媒和水媒传播的适应。