种子蕨的肉籽类Sarcocarpidiates古生代具果实的种子植物

Sarcocarpidiophytina,a Fruited Subphyta of Pteridospermophyta during Palaeozoic

苏铁纲、银杏纲、紫杉纲及买麻藤纲,由于胚珠的珠被里及假花被和套被里出现形成层,在受精之后形成层行次生生长,形成肉质的果皮,包着种子,起着保护作用,是雏形的果实,有别于后继的被子植物由子房(心皮叶)发育所成的果实,这种雏形果实从种子蕨类出现的初始阶段就已存在,并在种子蕨类占有优势和主流的地位,明显地存在着系统发育的意义.这一大类的种子包括上泥盆世的芦松Calamopitys、早石炭世的髓木Medulosa和皱羊齿Lyginopteris.与肉籽类在晚泥盆世出现的种子蕨类,包括狭轴羊齿Stenomylon、晚石炭世的华丽木Callistophyton、及盾籽Peltosperma代表着不具壳斗,珠被里不存有维管束,种子缺乏肉质保护组织,应归入狭义的种子蕨类.从晚泥盆世出现的第三支派的种子植物是科达Cordaites为代表的松柏类.

Since the spermatophytes arose from the Lower Devonian,there are lots of fruited plants existed.Within the integument of the embryo sac the vascular tissues were appeared,after fertilization the vascular bundle started secondary growth,and formed the protective tissue to the seeds,they are the primitive fruited plants before the Angiospermae appeared.These primitive fruited spermatophytes are the Calamopitys of Upper Devonia,the Medulosa and Lyginopteris of Lower Carboniferous,and after Permian there are the successors of Ginkgopsida,Cycadopsida and Taxopsida, as well as the Chlamydospermopsida .They are the principal seeded plants and more flourish than the other Tribes of Pteridospermae represented by the Stenomylon,Callistophyton and Peltosperma and the Cordaites during the Palaeozoic.