Seaweed Is Not a Weed and Not a Plant
Seaweed is marine algae. It is not a plant, it has no roots, and it turns up in more of your food than you would expect.
Seaweed is marine algae. It is not a plant: it has no true roots, stems or leaves, and it anchors itself with a holdfast rather than drawing nutrients from the ground. Extracts from it are everywhere in food — alginate, agar and carrageenan thicken ice cream, toothpaste and beer.
- Marine algae. *Seaweed on the tideline.*
- Edible varieties. *Dried seaweed sheets.*
- Seaweed as a modifier. *Seaweed extract fertiliser.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | seaweed | Green seaweed. |
| Related | algae | Marine algae. |
| Related | kelp | A kelp forest. |
| Related | nori | Sheets of nori. |
| Related | holdfast | Attached by a holdfast. |
How it is used in a sentence
- Kelp forests support entire ecosystems.Along many cold coasts.
- Nori is used to wrap sushi.A red alga, despite looking black.
- Carrageenan comes from seaweed.A common food thickener.
Seaweeds worth knowing
- Kelp — large brown algae forming underwater forests
- Nori — red algae, dried into sheets
- Dulse — a red seaweed eaten in Ireland and Scotland
- Laver — used in Welsh laverbread
- Bladderwrack — the brown weed with popping air bladders
A compound of *sea* and *weed*. The name is unfair: a weed is a plant growing where it is not wanted, and seaweed is neither a plant nor unwanted.
Is seaweed a plant?
No. Seaweeds are algae. They photosynthesise but lack the roots, vascular tissue and structures that define plants.
What is a holdfast?
The root-like structure that anchors a seaweed to rock. It grips but does not absorb nutrients.