It is a rare treat to get a personal letter from a reader asking a question – particularly one that arrives in the mailbox at the end of my driveway rather than the one the exists on the screen in front of me. This one even had a sample of a specimen accompanying the question. So, in pondering what to write about this week, the answer arrived just in time. Then, in looking back through old notes, I realized I had received a question from a reader about eelgrass last summer as well. So, it is obviously an organism that puzzles at least a couple of people and there are a few reasons why.

Plants don’t usually grow in the ocean. Of course, there are seaweeds of myriad types. But, actual plants aren’t well designed to live in an ocean environment. They often do better as free-floating bits of phytoplankton (tiny algae) that can drift from place to place or as larger leafy-looking algae, like kelps and rockweeds that can attach themselves to any hard surface they find and reach up towards the sunlight. These are all algae, not plants. There are two basic differences.

The first is that algae don’t have roots. They might have holdfasts, like kelp and rockweed, that look like roots. But these are not designed to slurp up nutrients like roots of a tree. Instead, algae are able to absorb their nutrients directly from the water they are floating in. That doesn’t make sense for land plants that stretch up into the air since the nutrients they need are in the soil. The second difference is related to the first – they don’t have a way to circulate those nutrients around like the veins you see in a leaf. Algae living in water don’t need to because all of their tissues are surrounded by a nutrient bath of sorts.

Eelgrass is different, though. It is perhaps the perfect example of a crossover species between land and sea. It has roots and it has veins, so it is a true plant. That also means that it flowers – something that most people don’t ever see. The flowers are incased within what looks like a fold in the eelgrass and that’s where the seeds develop. They look a little like a stalk of wheat, which makes sense since wheat is also a type of grass.

The piece of eelgrass that a reader sent in to me from Phippsburg was unusual because it was found in the winter and also because it was a part of a much longer piece. Most of the time we see eelgrass, it is just beneath the surface of the water. It can’t live very deep because it needs sunlight. It also needs a soft bottom for its roots. And, it can’t live in rough areas where the leaves could be thrashed about by crashing waves. All that equates to eelgrass being found in shallow, protected bays. It serves a critical role in these bays by providing oxygen to the water, providing habitat for many sea creatures, and stabilizing the sediment, among other important ecological functions.

Eelgrass commonly reaches lengths of a foot or so, waving its grassy leaves in clear, calm water. But, under the right conditions, it can get to be up to three feet long – the length observed by the reader who sent in the sample. It might also seem rare to see eelgrass in the winter. But, eelgrass is a perennial species with a mat-like root structure that persists through the seasons and will re-sprout in the spring. It even keeps tiny leaves that help to keep it alive. The piece of eelgrass that I received was washed up on the shores of Hermit Island in Phippsburg and had likely broken off sometime this summer given its silvery, dry appearance.

There have, however, been some unusual opportunities lately to see eelgrass out of the water during the unusually large tides we can get in the winter during the full and new moons. These can result in super high water as well as extremely low water. And, when there isn’t ice on the shore, you can see mats of eelgrass exposed and atypically out of water.

That said, eelgrass is a very important part of our ecosystem and finding it in any season is a good sign. It has the unique ability to live beneath the water but sometimes show itself above and also to help maintain the boundary between land and water by stabilizing the shore that is so critical to keeping the intertidal healthy. So, thank you for sending the question. I always welcome thoughts and questions from readers and appreciate opportunities to help broaden the knowledge of those interested as well as learn new things myself in the process.

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