Those who visit beaches around the Salish Sea at low tide may be familiar with eelgrass but may not know that is a flowering plant!

While walking on, or snorkeling over, our nearshore habitats, one may even see two species of eelgrass on the same beach. Though in some places they co-mingle, eelgrass (Zostera marina) is seen lower on the beach and has longer and wider leaves. On the other hand, dwarf eelgrass (Zostera japonica), also known as Japanese eelgrass, is found higher in the intertidal and is commonly shorter and thinner. In an article later this summer we will describe in more detail the differences between the two species, and between eelgrass and other seagrass species in the Salish Sea.

Eelgrass grows from an underground rhizome anchored by fibrous roots, often forming patches or even large meadows.

In the Salish Sea, eelgrass flowering heads (also known as flowering shoots) begin to appear each year as seawater warms in early spring. Although they grow from the same underground rhizome as vegetative shoots, these flowering shoots appear for only part of the year and then die back. Most of the eelgrass visible at the beach consists of the perennial vegetative shoots, which do not produce flowers and persist year round.

This video shows the expansiveness of the eelgrass meadow  during a maximum low tide at 4th of July Beach in the San Juan Island National Historical Park.  video by Tom Cogan

As a more familiar example of a plant’s seasonal life cycle, imagine if you will the very visible daffodil leaves emerging from an underground bulb. As daffodils begin to grow in early spring, their bright green leaves dominate the patch, similar to a patch or meadow of eelgrass at the beach. As aboveground growth continues, the white or yellow daffodil flowers appear on special flowering stems. The daffodil flowers are more visible in the patch until they wither in the fall and die, spreading seeds that become more bulbs.

Flat eelgrass vegetative leaves on left compared with round-ish yellow branching flowering head on the right. photo by John F. Williams

The erect stigma or female flowering part that receives pollen and receives pollen after which ovules are fertilized and seed development begins. photo by Gabriel Jacobs

The spathe is dynamic, for it is in this organ that flowers are pollinated and seed development takes place. With a careful and steady eye, one can observe pollination during sequential maximum low tide events in late spring and throughout the summer. One activity you can see is the outward expression as the female organs protrude from the spathe to receive pollen released by male organs and carried by seawater currents. This activity happens relatively quickly, and except for the protruding female organs, is rarely observed. If pollen is delivered, the ovule, now fertilized, becomes the site of seed development.

Fertilized ovules are also visible to the careful observer. Returning to the spathe, one will now notice features that appear very much like seeds because of their swollen appearance. It is exciting to know that the seed development stage is underway, and after 30 to 40 days from the appearance of female organs protruding from the spathe, the seeds are ripe.

The act of flowering captures human imagination. The seasonal appearance of a flower brings hope — hope that from life growing in the flower, a new generation will be born and life will continue.

The flowering parts of the eelgrass described above may not be easy to see at first. It helps to practice looking for them. These photos may help.

The previous photo is an example of how the light yellow flowering head appears to be cylindrical, and unlike the thin, darker green vegetative shoots, it doesn’t fall flat when slightly bent.

Next are some photos that show a flowering head from a distance (standing up), then even closer (squatting down), and then two views incrementally closer with a  close-up lens. The erect stigmas or female flowering parts poking out of the spathe were seen without harming the plant.

• Eelgrass restoration work in the San Juan Islands: Generations unite to protect San Juan Islands seagrass – Seacology
• Eelgrass makes noise! https://www.eopugetsound.org/articles/voice-eelgrass
• Eelgrass diagrams and life cycle information: https://depts.washington.edu/fhl/mb/Zostera_Jess/Life%20History.html
• Technical information about eelgrass and its conservation status: https://www.eopugetsound.org/articles/eelgrass
• Washington state eelgrass mapping: https://www.dnr.wa.gov/programs-and-services/aquatics/aquatic-science/puget-sound-eelgrass-monitoring-data-viewer

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Thanks so much for your interest and your support.