Members of the grass family, clumping bamboos that grow from short, underground rhizomes are typically native to the warm subtropical or tropical regions of the world. There are hundreds of clumping bamboos. The tightly clustered rhizomes form above-ground culms when temperatures are warm and soil is moist. Six common botanical groupings of clumping bamboos are found in gardens.
Clumping bamboos are species that grow from rhizomes--underground stems--that remain in a relatively compact cluster in the soil. Their plump, stumpy rhizomes are short and curve upward to emerge from the soil. These types of rhizomes are called pachymorphs. In contrast, leptomorph bamboos have rhizomes that grow horizontally and spread outward, thus called commonly "running" or invasive bamboos.
Most clumping, or pachymorph, bamboos hail from regions that are tropical or subtropical climates with ample moisture and little to no frost in winter; however, diversity shows species that grow at sea level as well as in highland mountains. Shorter and shrub-like species are usually from chillier regions, whereas tree-like clumping bamboos have origins in tropical areas.
A clumping bamboo's rhizome turns upward as it becomes a culm above the soil surface. It is always curved and just slightly wider than the culm, or upright stem. Roots emerge from the rhizome and new rhizomes develop from tiny eyes, or buds, on the main rhizome. The youngest or newest culms are on the periphery. Over time they become tightly clustered, forming a non-invasive clump; however, some clumping bamboo species have widely spaced culms, looking more like a diffused grove than a tight cluster.
Timing of Growth
Like invasive bamboos, clumping bamboos conduct most of their growth when garden conditions are warm and the soil is moist. Based on climate, the growth may not correlate to any season, but only to when both heat and rainfall events coincide, in either spring, summer or fall. Clumping bamboo culms take between 80 and 110 days to grow to 90 percent of their final heights.
Groups of similar species of clumping bamboos are called genera. Ornamentally important genera include: Bambusa, Chusquea, Dendrocalamus, Fargesia, Guadua, and Gigantochloa.