Usually a leaf blade is a thin, flattened organ, which is above ground for photosynthesis to take place. There are many other variations of the leaf blade that are not typical.
The leaf sheath is the part of the grass leaf that grasps the stem.
An awn is a bristle arising from the outer covering of the seed of a grass plant.
A rhizome is an underground stem of a plant that is usually found underground, often sending out roots and shoots from its nodes.
If a rhizome is separated into pieces, each part may be able to produce a new plant. This is a process known as vegetative reproduction.
A stolon is a stem that runs horizontally on, or just below, the soil surface. Plants with stolons are called stoloniferous. Rhizomes, in contrast, are root-like stems that may either grow horizontally at the soil surface or in other orientations underground.
A stolon is a group of individuals formed by a mother plant and all its clones produced from stolons form a single individual.