Understanding a bit about both can make it easier to maintain a lawn.
The basic grass plant structure is pictured to the left.
Below ground is the network of plant material called the root. All of the aboveground section of a grass is collectively called the shoot. Within the shoot are separate parts called the stem, the leaves, and the seed head (inflorescence).
There are two parts to a grass leaf. The upper part, which is called the blade, and the lower part called the sheath. The section where the blade and sheath meet is called the intercalary meristem, an area of cell division where new growth begins.
On most types of plants, this area of growth (meristem) is located at the tip (apical). On grass, this growth point is located below the tip (subapical).
The location is important because, when only the tip of the grass plant is cut away, and the meristem remains, the grass can grow a new tip.
Nodes are enlarged areas spaced along the stem of a grass plant. The vascular system of a leaf connects to the stem at the node. The node also is the connection point for buds which are able to generate new plants.
Grass roots and shoots meet at the crown. It is the thick, light colored part of the plant located at soil level.
The crown could be called the plant’s control center because it contains many nodes, each with an attached bud that could produce a new, independent plant, called a tiller.
Because the crown is at soil level, it escapes cutting and continues to support regrowth for trimmed blades and generate new tillers.
The ratio of tillers to dying blades determines the number of actively growing blades and thus, the density of the grass.