Seaside Panicum: A Pioneer in the Formation of Dunes

Seaside Panicum is one of those non-descript grasses on the dunes you’ve probably walked past and never paid attention to.  It has relatively wide leaves (compared to Sea Oats) and panicled seed heads that bloom a gorgeous combination of purple and orange in the fall.  But it turns out, this is an actual beach hero.  

Sand itself is made up of mostly inorganic materials: tiny grains of rock and some shell material.  Plants need both nutrients and moisture to survive.  So when sand is first blown and trapped by something on the beach to stop it, unless there are some plants to provide structure, it might just keep blowing again.  And the salty, sandy environment can seem pretty inhospitable to a growing plant.  We looked at the earliest colonizer, sea rocket, in terms of the role it plays in providing structure for growing plants in beach succession. But seaside panicum does more than just create a dune building structure: it actually changes the composition of the sand by establishing mycorrhizal fungi, which creates a more hospitable environment with subsequent plants that grow in the dunes.

Fungus amongus

The science about the crucial relationships between plants and fungi is pretty incredible stuff! Combining the words for the fungus (myco) and root (rhizi) gives us the word mycorrhizal to describe the relationship between the two.  Basically, I found a great video to explain it: you only need the first minute or so to see an animated explanation of how the plant provides sunlight and sugars to the fungus, the fungus spreads farther than the root to provide nutrients and water to the plant.

Well established, spreading roots

I was pretty fascinated by all this rooting magic, especially after reading Monica’s lovely 2020 post about the way the roots hold everything together, so I took some macro lenses and microscopic stuff out to see what I could find.

you can see how the roots reach throughout the dune
Where the roots run underground, tiny plants were sprouting up
the root system allows them to cling to the dune edges
the roots running near the surface seem to be encrusted somewhat
Looking a little closer at the roots which have been exposed
a really close look

To be clear, I am not completely sure what I am looking at~ I know some types of mycorrhiza develop within the root, and others develop externally.  But I thought the textures of these roots were fascinating.  This was in the deep of winter~ I might check again in summer.  This is the fun of learning about nature: there is always something more to learn! The tiny slips of plants from March were about an inch tall in April.

Panicum refers to the Panicles, or seed heads

These are so pretty in the fall, with tiny flowers that become seeds that are eaten by birds and beach mice.

Enlisting the Assistance of Seaside Panicum with Sea Level changes

Panicum can be an effective dune stabilizer, and we’ve seen how all those intertangled roots can hold the dune in place even during times of king tides.  They may not prevent the process of erosion, but they can at least slow it down.

The Dewees Island Conservancy has been addressing the issue of a dune breach that left our maritime forest open to the effects of moving salt water, and a dune was constructed to help create a barrier to protect that marsh and forest.  The sea rocket seems to have effectively colonized itself, but the strategy has been to wait to plant any sea oats until the panicum has created the optimal soil conditions.