科达树(学名:Cordaites)是一属已灭绝的树状植物,与种子蕨类同样由前裸子植物演化而来,为现今银杏类与松柏类植物的祖先。[2]科达树既生长在干旱地区,也能生长在与佛罗里达州大沼泽地相似的湿地中,常在其树根部位发现咸水淡菜类和甲壳类的化石。它们的化石被发现于全球各地的上石炭纪地层中。[2]
特征
科达树的植株很大,可达30公尺。带状的叶于枝条上排列成紧密螺旋状。叶上有独特的平行脉。[2]其繁殖器官被称为科达穗(Cordaianthus),为单性的,但不易分辨其雌雄。花粉为颗粒状的弗氏粉属(Florinites),直径约50微米,尚未发现其花粉管。球果位于枝条的末梢。[2]种子亦不少见,外型相当大,大小从二、三毫米至2厘米不等,呈扁心形,可分为高特果(Cordaicarpus)、心果(Cardiocarpus)和翅果(Samaropsis)三种。
物种
- Cordaites daviessensis
- Cordaites hislopii [3]
- Cordaites kinneyensis
- Cordaites ludlowi
- Cordaites lungatus
- Cordaites minshallensis
- Cordaites olneyensis
- 带科达 Cordaites principalis
参考文献
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