Marine macro-algae (seaweeds)

The marine macro-algal groups Rhodophyta, Ochrophyta and Chlorophyta (collectively known as seaweeds) represent the largest part of the algal collections.


The seaweed collections consist of:

  • dried/pressed herbarium specimens
  • boxed bulky specimens (eg coralline algae-encrusted rocks)
  • microscope slides
  • liquid-preserved material

More information

  • Coralline algae - crustose and maerl
    British coralline algae collection

    Coralline algae species are major structural and ecological components of ocean bottom communities. The specimens in this collection span nearly 150 years. Find out more.

  • Isles of Scilly
    Seaweed fieldwork

    Catch up with a couple of our latest collecting expeditions.


Claudea elegans

Claudea elegans, an unusual and beautiful red seaweed collected from Tasmania by the eminent phycologist William Henry Harvey in the 19th century.

The taxonomic and geographical range of the seaweed collection is broad and associated with a significant amount of information. 

The UK is particularly well represented with a timeline of specimen data going back more than 250 years.

The herbarium has a global coverage, with spectacular early collections from Australia, New Zealand, South Africa, North and South America and the Falkland Islands.

There are also significant contemporary collections from West Africa, Oman, United Arab Emirates and Iceland.

Taxonomic strengths include collections of the genus Porphyra and an extensive collection of coralline algae.

Current projects


Rhodophyta (red algae)

The Rhodophyta is the most species-rich macroalgal division, with more species than the green and brown seaweeds combined. This richness is reflected in the complexity and diversity of red algal morphology and anatomy. The group is primarily marine, with some freshwater representatives.

Ochrophyta (brown algae)

The brown algae range in size from single-celled organisms to giant kelps which may be more than 50 metres in length. They are mostly marine organisms although there are also some freshwater representatives with microscopic branched filaments.  

Chlorophyta (marine and freshwater green algae)

This diverse group includes the freshwater and terrestrial green algae, such as charophytes, desmids and Spirogyra, and the marine green algae, such as the common seaweed Ulva lactuca (‘sea lettuce’).

British seaweeds