Aquatic, Wetland and Invasive Plant Particulars and Photographs University of Florida Aquatic, Wetland and Invasive Plant Information Retrieval System

Some definitions of terms.

We use the common names of the U.S. This may be confusing to web surfers from other parts of the world. After all, our cat-tails are their bulrushes, our bulrushes are their club-rushes, their rice grass is our cut-grass. And our common names are confusing as well. For example, saw grass is not a grass, but a sedge. And the only true rushes shown here are the bog rushes of the genus Juncus. (The bald-rushes, beak-rushes, bulrushes, club-rushes, lake rushes, spikerushes and star-rushes are all sedges!)


Here are several descriptions that must be remembered if you really want to be able to identify plants, particularly the grasses, sedges and rushes. There are many other parts and terms of course (see our Glossary), but here we describe only the terms used in these plant descriptions.


Some leaves have sheaths. The sheath is at the base of the leaf blade and it may completely surround the stem, or it may not. The sheath may be short or it may be very long.


Another part is the ligule. The ligule is an outgrowth at the junction of the leaf blade and the leaf sheath. The ligule may be hairy, or bristly, or hard or soft or may be absent altogether.


An inflorescence is a structure that holds the flowers of a plant. There are different types of inflorescences having various degrees of complexity. Often, inflorescences are described as being closed or opened. The main axis of an inflorescence is called a rachis. The rachis may have few branches, or many branches. The branches may be further divided into branchlets.


The inflorescence may have structures called spikelets. Spikelets are parts that contain the flowers of the plant. Spikelets may grow in rows, or in spherical clusters, or in other arrangements. Depending on the species, spikelets may be extremely small, or quite large, an inch or more long. Spikelets often have scales and/or bristles.


The base of the inflorescence or its branches may have bracts. Bracts are leaf-like parts that may be very small and inconspicuous, or they may be relatively large or long, in which case they may be mistaken for leaves.


The individual flowers of grasses, sedges and rushes are usually not conspicuous and colorful like the flowers of other plants. In fact, non-botanists often don't recognize them as flowers at all, even when magnified. The flowers may be so tiny that they require a magnifier to see, such as in Juncus. Or they may be so numerous that they are very obvious, such as in Phragmites.