meristem

Region of plant tissue containing cells that are actively dividing to produce new tissues (or have the potential to do so). Meristems found in the tip of roots and stems, the apical meristems, are responsible for the growth in length of these organs.

The cambium is a lateral meristem that is responsible for increase in girth in perennial plants. Some plants also have intercalary meristems, as in the stems of grasses, for example. These are responsible for their continued growth after cutting or grazing has removed the apical meristems of the shoots.

Meristem culture involves growing meristems taken from shoots on a nutrient-containing medium, and using them to grow new plants.

It is used to propagate infertile plants or hybrids that do not breed true from seed and to generate virus-free stock, since viruses rarely infect apical meristems.