Coralloid roots A type of root regularly produced by cycads, which contains symbiotic nitrogen-fixing cyanobacteria in root nodules, giving the roots a knobbly coral-like appearance.

• 珊瑚状的根：由苏铁类植物产生的一种类型的根，根瘤中含有共生的固氮蓝细菌，使根形成珊瑚状的有节的形状。