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GRASS FLOWERS

Annual Bluegrass, Poa annuaIf all you know about grasses is that they are the stuff of lawns, then you will be surprised by just how complex, pretty and interesting grasses can be. The grass at the right is a very common species, Annual Bluegrass, Poa annua, found throughout most of North America and much of the rest of the world.

Note that this plant has roots, leaf blades, stems, and an inflorescence of flowers atop the grass plant. In short, it has everything any other plant has. Now look at this:

Annual Bluegrass flowers showing parts of the spikelet

The image above and to the left shows an Annual Bluegrass  spikelet -- something not found in our Standard Blossom. This shows that the world of grass flowers is a special one. Other flowers do have the anthers shown in the picture but "florets" and "glumes" are particular to the grass family. Therefore, here are two points about getting to know grass flowers:

  • once you get to looking at them closely, you see that there are many, many details to help you identify them
  • even if you already know basic flower anatomy, when you start looking at grass flowers, you will need to learn a few new concepts -- but that's fun

Four grass inflorescencesThe Grass Family is another of the "Big Three" plant families,  along with the composites and orchids. Like those families, grasses have evolved in fairly modern times (geologically speaking) and, even more than the composites, grass flowers are masters of miniaturization, simplification, and fusion. 

At the right you see the inflorescences of four different grasses, each collected within 30 feet of my door.  Each of the very different clusters bears dozens of flowers (the one on the far right hundreds). From left to right, the grass species shown are Uniola (Uniola sessiliflora), Virginia Wild Rye (Elymus virginicus), Purpletop (Triodia flavus) and, Johnson Grass (Sorghum halepense).

Bamboo flowersThe picture at the left shows another close-up of a grass inflorescence -- in this case the grass is a species of bamboo growing near my home. In the top, left quarter of the picture  you see a spikelet consisting of three or four grass flowers (called florets) growing together. From each flower you see some stamens dangling out, and of course stamens are the male parts of a flower. The very slender, white strands emerging from the flowers are the stamens' filaments, and at the bottom of each filament you see the yellowish anthers, from which pollen is shed.

Blue Grama, Bouteloua gracilis,Don't let the grasses' "simplicity" drive you away, for they are a satisfyingly challenging group! First of all, just in the U.S. there are around 1,400 grass species! Once you learn the five or so common weedy species in your backyard, such as crabgrass and Bermuda grass, then you can branch out by going to look for "specialty species" -- species found only in particular habitats, or geographic regions.

What a thrill to find the weird Hackelochloa granularis, a native of tropical Africa and Asia, but sometimes escaped in the U.S. Deep South. Or the attractive Glyceria obtusa, found only in bogs along the U.S.'s Atlantic coast, or the Blue Grama, Bouteloua gracilis, which in the U.S.'s Great Plains and western mountains grows in dry places and is an important food for browsing wildlife and livestock. The Blue Grama's species name, gracilis, means "graceful," which the photo of that species above and at the right supports.

Wild Rye, Elymus virginicusWild Rye, elymus virginicus closeupBut what's really fun with grasses is to see how many interesting ways nature has found to put together the few, simple grass flower-parts. Of course, to see these ways you really need to have a good handlens, and be willing to snoop deeply. At the left is an inflorescence of the Wild Rye, Elymus virginicus. At the right is a closeup of the same picture. Just look at how the yellow anthers are dangling out, and note the curious way the glumes are formed at the base of each spikelet.

With grasses, more than with any other group of flowering plants, perhaps, we can have fun with "variations on a simple theme." If you care for Bach fugues, you'll love grasses...

You may enjoy looking through Jim's Field Notes on grasses he's met.

Some wonderful grass books are available. For instance, available online at Amazon.com there's the beautiful little classic Agnes Chase's First Book of Grasses : The Structure of Grasses Explained for Beginners as well as How to Identify Grasses & Grasslike Plants : Sedges and Rushes. A massive, comprehensive volume for the really serious is The Biology of Grasses.

Grass books:

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Conrad, Jim. Last updated . Page title: . Retrieved from The Backyard Nature Website at .