Algal herbarium

Herbarium sheet showing Halidrys siliquosa.


Nina Lundholm

Collection manager

Christian Lange

About the collection

The collection holds around 400,000 species roughly estimated, covering all taxonomical groups of algae from different parts of the world. The collection has a focus on macroalgae and among the microalgae on diatoms with more restricted collections of other groups of microalgae. It holds the largest collections of Danish macroalgae with an almost complete coverage, and has important collections from Greenland, Iceland, the Faroe Islands, the Canary Islands, the West Indies and Scandinavia.

The most important historical part of the collections includes Pehr Forsskåls collection of algae from a journey to Arabic countries; mentioned in Flora Aegyptiaco-Arabica 1775.

A diverse and large collection of marine and freshwater diatoms from all around the world, including many types. These originate from Lyngbye (1782-1837), E. Østrup (1845-1917), J.B. Petersen (1887-1961), and N. Fogeds (1906-1988) collections.

The collection of macroalgae is huge and diverse and dates from Pehr Forsskål (1732-63) , covering e.g. H.C. Lyngbye, L.K. Rosenvinge, F. Børgesen and presently ends with the former curator R. Nielsen, who is still active in the museum.

Danish macroalgae from marine and brackish waters in Denmark includes 500 species of Cyanophyceae (Nostocophyceae), Rhodophyceae (Bangiophyceae), Phaeophyceae (Fucophyceae), Xanthophyceae (Tribophyceae), Charophyceae and Chlorophyta.

Regarding Arctic algae (Iceland and Greenland), the main collections start already in 18th century with H.C. Lyngbye L.K. Rosenvinge and E. Østrup (1845-1917), up to the more recent F. Børgesen, H. Jónsson, S. Lund, N. Foged, I. Munda and R. Nielsen.

Faeroese collection: H.C. Lyngbye, visited the Faroe Islands in 1817. A few specimens are included in the database, while most of the Lyngbye herbarium is not. His collections are kept as a special collection. F. Børgesen, visited the Faroe Islands in 1895-1900 and 1902. D. E. G. Irvine et al., 1980. R. Nielsen et al., 1994-2000 under the programme known as BIOFAR 2.

Algal herbarium in numbers

  • Estimated number of specimens/collections: Approx 400,000 specimens/samples
  • Types: Approx 2025
  • Digitally available specimens: c. 80,000
  • Percentage digitized: c. 25%

Delessera sanguinea, Cladophora glomerata and Spaerotrichia divaricata (Photos Ruth Nielsen).


  • Type of Sargassum dentifolium from Forsskåls herbarium.

    A diverse and large collection of diatoms from all around the world (including many types) from e.g. Lyngbye, E. Østrup, J.B. Petersen and N. Fogeds collections. 
  • A diverse macroalgal collection focusing on taxa from Denmark, Greenland, Iceland, and The Faeroe Islands.
  • P. Forsskål's collection of algae including many types. Pehr Forsskål's herbarium was collected during the expedition to “Arabia Felix” (present Yemen) in 1761-63 and holds several algal specimens, many of which are type specimens.
    References: F. Børgesen, 1932. A revision of Forsskål’s algae mentioned in Flora Ægyptiaco-arabica and found in his herbarium in the Botanical Museum of the University of Copenhagen. Dansk Botanisk Arkiv 8 (2) 1-14.

Important subcollections

  • Christoffer Heerfordt (1609-1679): Herbarium sheets of Charophytes from Danish waters.
  • Pehr Forsskål (1732-63): Algae from a journey to Arabic countries; mentioned in Flora Aegyptiaco-Arabica 1775. Historical value and includes types.
  • Nicolaus Hofman Bang (1776-1855): Historical value mainly. Dried material, macro and microalgae.
  • Hans Christian Lyngbye (1782-1837): Marine macroalgae and microalgae (mainly diatoms) from Denmark, Norway and The Faeroe Islands. Dried material. Includes types.
  • Herbarium sheets from Caroline Rosenbergs collection.

    Caroline Rosenberg (1810-1902): Danish macroalgae. Dried material.
  • Povl Klavsen (1878-1918): Diatoms, mainly raw and rinsed samples. Neatly arranged diatoms.
  • Ernst Østrup (1845-1917): Diatoms from Denmark, Greenland, Faeroe Islands, Iceland and elsewhere. Permanent slides, rinsed and raw samples. All numbered with correlating numbers. Includes >400 types.
  • Lauritz Kolderup Rosenvinge (1858-1939): Mainly macroalgae from Denmark and Greenland. Permanent slides, dried specimens and slides. Cyanobacteria (permanent slides).
  • Frederik Børgesen (1866-1956): Marine macroalgae (Rhodophytes, Phaeophytes, Chlorophytes) from The Faeroe Islands and many places around the world like The Virgine Islands, The Canary Islands, India, The Iranian Gulf and Mauritius. Microscopic slides, ethanol preserved and dried material. Including many types. Desmids (Microscopic slides).
  • Johannes Boye Petersen (1867-1961): Aerofile and earth living algae, mainly diatoms and green algae. Dried samples and microscopic slides. Includes types.
  • Carl Hansen Ostenfeld (1873-1931): Marine and freshwater plankton. Permanent slides.
  • Julius Grøntved (1899-1967): Permanent slides of mainly diatoms and dinoflagellates. Includes types.
  • Gunnar Nygård (1903-2002): Plankton samples mainly from Denmark and Greenland. Permanent slides , dried and fixed samples. Includes types.
  • Berit Asmund (1904-1985): Freshwater chrysophytes from Denmark and abroad. Slides and plankton samples. Folders with photos of species.
  • Søren Lund (1905-1974): Macroalgae. Permanent slides and formalin-fixed samples. Encrusted algae on stones from Denmark and Greenland.
  • Niels Foged (1906-1988): Diatoms from all around the world, including permanent slides, rinsed and raw material. Includes >500 types.
  • Max Møller (1909-1974): Diatoms with mainly permanent slides as well as a photo-collection of species. Includes types. Includes material from Rabenhorst and Østrup.
  • Tyge Christensen (1918-1996): Macroalgae (Rhodophytes, Phaeophytes, Chlorophytes). Main collection of Vaucheria. Microscopic slides, formalin-fixed samples and dried material.
  • Sigurd Olsen (1908-xx): Danish Charophytes (publ 1944). Dried material.
  • Wadden Sea: Slides of diatoms from the Wadden Sea 1980-1983. Collectors: Tyge Christensen, Hanne Kaas, Claus Koch, Jacob Larsen and Helge A. Thomsen. With report for the Danish Research Council.
  • Ruth Nielsen (1944- ): Collection of macroalgae from Denmark, Iceland, the Faeroe Islands. Dried material and microscopic slides. Includes types of e.g. Ulvellaceae.
  • Poul Møller Pedersen (1945-2012): Macroalgae mainly from Greenland. Dried material. Includes types.
  • Jørgen Kristiansen (1931- ): Chrysophytes from Denmark and abroad.
  • Aase Kristiansen (1933- ): Macroalgae, mainly Danish. Dried material.

N. Hofman Bangs herbarium including the type of Bangia fuscopurpurea.

Important exciccates in the collection

  • Charophyes excicates (Karczmarz, Braun, Rabenhorst, Sitzenberger, Nordstedt, Wahlstedt, P. Nielsen)
  • Algae Scandinavicae Exsiccatae (Areschoug)
  • Phycotheca Boreali-Americana (fasc. A-E) (Collins et al.)
  • Algue marines du Finistères (Crouan)
  • Algarum aquae dulcis Germanicarum (Kützing)
  • Algue de la Guadeloupe (Mazé & Schramm)
  • Algen Sachsens (Rabenhorst)
  • Algen Europas (partly) (Rabenhorst)
  • Algae aqua dulcis Exsiccatae

The Margrave herbarium, Galaxaura, species no 113.


Some of the earliest preserved algae in the museum are found in two plant herbaria from the 16th century.

The Margrave herbarium collected in Brasil by G. Margrave in 1638-1644 holds one algal specimen of Galaxaura.

Reference: D. de Andrade-Lima et al. 1977. Margrave’s Brazilian Herbarium collected 1638-44. Botanisk Tidsskrift 71:121-160.

The Heerfordt herbarium from c. 1650 consisting of plants from the islands of Lolland and Falster, Denmark also holds two algal specimens of Chara: C. baltica and C. aspera.

Reference: J. Lind 1917. Apoteker C. Heerfordts Herbarier. Botanisk Tidsskrift 36:1–19.
Outline of Phycology in Denmark. J.B. Hansen 1985.

The Heerfordt Herbarium.

Former curators:

  • Jørgen Bendt Hansen (1917-1987): focus on diatoms.
  • Ruth Nielsen (curator 1987-2011): focus on Nordic macroalgae. Ruth is professor emerita at the museum and is actively collecting and doing research.

Cupboard with herbarium sheets of macroalgae with colored labels after geographical region and red covers for types. Boxes with microscopic slides from Fogeds collection. Cigarboxes with samples from Østrups collection.