Cycadophyta (cycads) A phylum of cone-bearing gymnosperms (about 75 living species) with palmlike compound leaves and special CORALLOID ROOTS at or near the ground surface, which contain symbiotic nitrogen-fixing cyanobacteria.
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- 苏铁纲(苏铁类植物):包含球果的一类裸子植物(现存种大约有75种),它们具有掌状的复叶,在近地面处有特殊的珊瑚状的根,根内含有共生的固氮蓝细菌。