If you've read through our Grass Flower page and maybe looked at a few grasses around your own house, you might decide that they are. But only one of the three species belongs in the Grass Family. Can you figure out which?
OK, here's what appears at the right:
On the far left, that's our grass, Bluegrass, Poa pratensis. The other two species are sedges, members of the genus Carex, and the Sedge Family -- not the Grass Family.
When we speak of the Sedge Family we are referring to genera and species in the Cyperaceae. Such plants are not grasses because they are not members of the Grass Family, the Poaceae. The best-known members of the Sedge Family are the sedges themselves, (genus Carex). However, several other members of the family are often common in some backyards as well. There are, for example, umbrella-sedges (genus Cyperus -- that's a typical one shown at the right), spike-rushes (genus Eleocharis) and bulrushes (genus Scirpus). Differentiating the many, many species in each of these genera is a joy for the really serious, but simply mind-boggling for most of us.
How is the Sedge Family different from the Grass Family? There are important differences if you just look. The differences easiest to see are that grass stems are usually but not always round in cross section, while sedge stems are more or less triangular.
Also, look at the picture at the left. Both of the items you see are stems arising from blade sheathes. Typically blades (leaves) in the Grass Family and grass-like families form a kind of cylindrical covering that wraps around the stem below the point where the blade meets the stem, and covers the stem below that point, all the way until a node is reached. (Nodes are explained at the bottom of our Stem Page.) In the picture, the sheath on the right is split, and that's the way it is with most but not all species in the Grass Family. On the left, however, there is no split, and that's the way it usually is in the Sedge Family!
In the above picture you can also vaguely see that the sedge stem on the left is more or less triangular, but the grass stem is definitely round. To get this sheath concept fixed in your mind, right now you could go outside, pull up a grass stem and notice how the blade forms a sheath when it meets the stems, that that sheath is split, and the stem is round.
When we refer to sedges, we're speaking of species included in the genus Carex, a member of the Sedge Family, or Cyperaceae. Just in the northeastern quarter of North America, over 200 species of Carex are known, and some of them are very common. The one shown at the right, Carex frankii, is from beside a spring right below where I live as I write this.
Note that the male and female flowers are in different parts of the flowering spike. The shape, size, and distribution of flowers in Carex is endless -- therefore, fun to play with! In some species the male flowers arise above the female, opposite to this species. In some species, there is only one spike instead of the several this species has. Most sedge fruits don't have the narrow, hairlike "necks" this species does. Some flower spikes are round, some thick, some thin... on and on the variations go.
When I was a student, I identified 32 members of the Sedge Family just in my small, western Kentucky home-county, of which 22 were sedges!
Rushes are members of the, genus Juncus, in the Rush Family, the Juncaceae. One is shown at the right.
Most rushes like wet places but there are some extremely common ones that grow along paths, called Path Rushes. If you walk along a trail in a city park there's a good chance you'll see Path Rushes, so look for them. Notice that the fruiting capsule in the orange square is spherical, not at all compressed as among the grasses.
Also certain genera in the Lily and Iris Families sometimes look like grasses.
Well, we could go on and on, but here is the point: We have seen that the Grass Family is a huge, wonderful family with every kind of variation upon a grass-flower theme, and now we see that beyond the Grass Family there are jillions of grass-like things just as engaging and just as mind-bending.