Grass, at first glance, may seem like a very simple plant. On further examination. however, it becomes apparent that there are several different and distinct parts to a grass plant. The form of each part can vary greatly from species to species. Understanding the parts and their differences is essential for accurately identifying the type of grass being examined.
Rhizomes are stems that form underground. As the rhizome continues to grow, it forms new grass plants, vegetatively. Rhizomes also put out roots that serve to draw water and nutrients into the plant from the soil.
Stolons, are above ground stems of the grass plant. Often referred to as "runners," these can trace across the surface of the ground, put down roots and start new grass plants.
Node and Sheath
The node is the point on the stem where a new sheath for a leaf begins to grow. The sheath is the part of the leaf the wraps around the stem. The edges of the sheath may not meet at all, may be joined together, or may even overlap.
The collar is the portion of the leaf where the blade and the sheath meet. Collars may be continuous in some species, wrapping completely around the stem or may only wrap partially around.
Auricles are projections from the outside edges of the collar. They may be long and claw-like, short and stubby, or absent altogether, depending on the species.
The ligule is the structure that holds the blade to the sheath. Some species of grass have a membranous ligule, while other ligules are hairy projections. In some species, the ligule is entirely absent.
The blade is the part of the leaf that protrudes from the stem. The blade usually has a midrib running down its center. The texture, size and tip of the blade are often used in identifying specific species of grass.
The seed head is the uppermost portion of the plant. It contains the flowering and seed producing parts of the grass plant, which can be a number of different configurations, depending on the type of grass. The seed head is frequently used as an identifying feature of the plant. Seed heads can form panicles, which are small branching structures with seeds on the ends of each branch, spikes, where all of the spikelets are connected directly to the stem, or slender spikes emanating from either the tip or the side of the stem.
The spikelet is the part of the seed head that makes up the seeding part itself. They can form in clusters, as single seeds, or as bundles of several seeds.