perennial rushlike flowerless herbs with jointed hollow stems and narrow toothlike leaves that spread by creeping rhizomes; tend to become weedy; common in northern hemisphere; some in Africa and South America
In the clubmosses and horsetails only one type of strobilus is formed, while in the gymnosperms female megastrobili and male microstrobili both develop. 石松和楔叶类只形成一种类型的球果，然而裸子植物既有雌性的大孢子叶球也有雄性的小孢子叶球。
Some giant horsetails and Cordaitales reached nearly 100 feet. 有些巨大的木贼类和科达目植物高度达到一百英尺。
