|This species has very thick walled culms. Thes nearly solid culms are often used to make umbrellas. Bamboo is a common term for a large number of giant grasses that include many different species and varieties. There are two main types of bamboo. Runner types send out underground stems to varying distances that send out vertical shoots. These will grow in large thickets or groves if left alone. Clump bamboos have underground stems that sprout vertical shoots much closer, growing slowly outward.