Identifying Types of Grass
Sometimes, lawn lovers want to know whether the grass they are growing in their lawn is a lawn plant or a weed grass. My experience is that most garden center staff really cannot help with this problem because they are not trained in grass or turf management.
What follows here is a basic course in grass leaf identification that will let you go out to your garden and identify all the different kinds of grass you are growing. Each of the grasses listed in the rest of this chapter is described using these anatomical structures, so you can take the information outside, lie down on the grass, and sort things out. To accomplish this job, however, you do have to stay awake while lying on the grass.
Let's start with the collar. This is where the blade of grass and sheath meet on the individual grass leaf. You can almost forget the collar because on most grass species, you won't be able to see it unless you're a trained botanist with a hand lens.
I include it only because it's there and because on some species, it can be useful. If it is important, it will be listed under the appropriate grass species.
GOOD ROOTS = GOOD GROWTH
Good roots on a plant almost always equal good tops and good growth. Emphasize the gardening techniques that grow good roots and you'll automatically have a good plant. This is as true for grass plants as it is for any other plant in your garden. You have to remember that your lawn is not a single thing; it is composed of thousands of individual grass plants, each with its own specific needs for growth and health. You are growing a lot of individual plants in that lawn so you have to take good care of them. Start with the roots.
The sheath, the rounded part of the grass leaf, runs between the collar and the leaf node. There are three kinds of sheaths: (1) split down its entire length, (2) split part of the way, or (3) closed along its entire length.
Most good turfgrasses have sheaths that are split down their entire length. A split sheath will not help you identify which good grass you've got. However, if a sheath is not split along its entire length, you know it's probably a weed species. This is your first clue to weed grasses.
Look on the inner side of the grass leaf where the blade meets the sheath (the collar area). This is where you'll find the ligule. This tiny bit of botany is our first important feature. It will distinguish between the kinds of grass you want to grow in a grass family and those you don't.
There are three kinds of ligule distinctions: (1) a “hairy” ligule with small hairs (the hairs are different lengths for different grass species), (2) a membrane ligule that resembles a small bit of skin, or (3) the complete absence of one.
Again, look at the collar area of your grass plant. There are three ways that the collar can join at the front of the sheath to form the auricle. This front of the collar area is quite distinctive and very useful in identifying grass species. Again, there are three choices: (1) long auricles that overlap, (2) short auricles that do not overlap, and (3) no auricle at all. In men's dress shirts, the analogy would be to the long pointed collars of the ‘70s, the button-down, non-overlapping collars of the ‘80s prep school, or the no-collar look of the ‘90s.
The tip of the leaf sometimes provides good identification clues. The first type is a pointed tip that looks like the sharp end of a pencil. The second type has tips shaped like the bow of a boat, with a rounded edge leading to an upfacing point, or simply two parallel sides coming together. A small trick to keep in mind if you are having trouble determining whether a leaf is boat shaped or pointed is to hold the tip of the grass leaf between your thumb and forefinger very gently and slowly apply pressure. If the leaf is boat-shaped, it will likely split into two parts under increasing pressure, while a pointed leaf will simply crush.
Vernation is the last characteristic to be considered. Again, this is very helpful when trying to distinguish between the good guys and the bad guys in a particular grass family. Vernation describes how the new grass blade comes out of the sheath. Is it folded or rolled? That's the difference, and you'll use it to tell the weedy grasses from the good grasses.
Now, that wasn't hard, was it? Time to play Sherlock Holmes.