Seagrass: the quiet life beneath the water

Beneath the surface of the sea lie entire meadows that most of us will never see. Their slender leaves sway with the current. They shelter marine life, steady the seabed, and quietly store carbon. And their story begins somewhere unexpected: with a flower.

What is seagrass?

Seagrass is not seaweed. Seaweeds are algae, while seagrasses are true flowering plants, with roots, leaves, flowers, and seeds, whose whole life cycle has adapted to the sea. They belong to several genera, including Zostera, Thalassia, and Halodule. Their long, ribbon-like leaves bend with the water rather than resisting it.

Where seagrass grows

Seagrass grows in shallow coastal waters around the world, from tropical lagoons to cooler temperate shores. It stays shallow because it needs sunlight to reach its leaves. Each species has its own needs, but all ask for the same essentials:

• Water: seawater of the right salinity for the species.
• Light: clear water, so sunlight can reach the leaves.
• Seabed: stable sand or mud where roots can anchor.
• Temperature: from tropical warmth to temperate cool, depending on the species.

A seed unlike any other

Seagrass seeds are small, often oval or elongated, and brown in tone. Once released, some drift before settling into the sediment, where they may lie dormant until conditions are right.

Unlike most garden seeds, many cannot be dried and stored in a jar; they must stay moist to survive. Scientists restoring lost meadows have studied this closely. In one study, eelgrass (Zostera marina) seeds were kept viable for around 17 months, stored wet at 0°C in water saltier than the open sea (Global Ecology and Conservation, 2020).

From seed to underwater meadow

In good conditions, a seed can germinate within days or weeks. The seedling must then root itself against currents, grazing animals, and shifting sediment. Once established, it spreads through underground stems called rhizomes, sending up new shoots until, over years, a meadow forms. Where meadows are lost, recovery can take many years, and is never guaranteed.

Why seagrass meadows matter

Seagrass is one of the ocean's quiet workers. Its leaves slow the water so particles settle, its roots bind the seabed against erosion, and its meadows shelter and feed a wide range of marine life. Seagrass also stores carbon in its roots and in the sediment beneath it, making meadows an important coastal carbon sink.

Yet these habitats face pressure from coastal development, pollution, murky water, destructive fishing, and a changing climate. Protecting the meadows that remain matters as much as planting new ones.

How seagrass becomes a fibre

Once harvested and dried, seagrass can be twisted and woven into bags, baskets, and home pieces. Its colour ranges from soft green to gold and warm brown, depending on the species and how it is dried. Because some species are protected and wild harvesting can harm fragile habitats, the origin of the fibre matters as much as its beauty.

Seagrass at COLĒRE

Our Ocean Dreams bag and Aether & Me pair seagrass with abaca, handwoven by fairly paid artisans in small batches. To learn about its partner fibre, read Abaca: the quiet strength of a tropical plant.

To care for a material is also to care about where it comes from. That is The Art of Care.

Seagrass questions, answered

Is seagrass the same as seaweed? No. Seagrass is a flowering plant with roots and seeds; seaweed is an alga.

Where does seagrass grow? In shallow coastal waters around the world.

How does seagrass reproduce? Through seeds and through underground rhizomes that send up new shoots.

Why is seagrass important? It shelters marine life, stabilises the seabed, and stores coastal carbon.