Seaweed is not a true plant but a type of algae that lives attached to rocks underwater.

The longer version

True plants have roots, stems, and leaves with internal tubes for transporting water and sugar, and they develop from an embryo protected inside the parent. Seaweeds lack all of that, belonging instead to several groups of algae whose bodies are comparatively simple.

Instead of roots they use a holdfast, an anchor that grips rock but takes up little. Every part of the body can absorb nutrients straight from the water, so there is no need for a transport system. Many species stay flexible to survive waves, and their colour depends on which pigments they carry.

Where this entry sits

Plants and Trees gathers ordinary and surprising details about how green things live, from the tallest forest giants down to the moss on a garden wall. Expect notes on flowers, seeds, roots, leaves, fungi, and the quiet tricks plants use to spread and survive. The full list sits on the Plants and Trees page, where every entry is listed in order.

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More From Plants and Trees

Eight more entries

Grass recovers quickly after being grazed because it grows from the base rather than from tips.

Dodder is a twining parasite that wraps around other plants and draws nourishment from their stems.

Sensitive plants fold their leaves inward within seconds of being touched, then reopen a short time later.

Baobab trees store water in their swollen trunks, helping them endure long dry seasons in Africa.

Tree roots usually spread far wider than the crown above them, often reaching well beyond the canopy.

Photosynthesis turns sunlight, water, and carbon dioxide into sugar, releasing oxygen as a by-product.

Transpiration pulls water up through a plant as it evaporates from tiny pores in the leaves.

Bulbs such as onions and daffodils store food underground so the plant can regrow each spring.

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