Book review on "Danmarks Havalge" 1 and 2

Submitted by Tina on 14 January 2020.

By Stein Fredriksen, University of Oslo, Norway

Marine benthic algae, or seaweeds, have received increased attention during the last years, in particular those species that are used for cultivation. Their use can be anything from food items to additives in cosmetics. The recent shift towards a more plant-based diet in humans, including algae, requires knowledge of this group of organisms and new and updated floras are also therefore welcomed. Two new flora on macroalgae from Denmark have recently been published:

  • Ruth Nielsen and Steffen Lundsteen 2019 Danmarks Havalger. Volume 1 Rødalger (Rhodophyta). The Royal Danish Academy of Sciences and Letters, Scientia Danica, Series B Biologica, Volume 7, 398 pages. ISSN 1904-5484. ISBN 978-87-7304-421-6


  • Ruth Nielsen and Steffen Lundsteen 2019 Danmarks Havalger. Volume 2 Brunalger (Phaeophyta) og Grønalger (Chlorophyta). The Royal Danish Academy of Sciences and Letters, Scientia Danica, Series B Biologica, Volume 8, 476 pages. ISSN 1904-5484. ISBN 978-87-7304-422-3

The introduction starts with a brief history of Danish algal research with a special focus on the Danish algal herbarium which have collections back to around 1656. This is followed by a section covering conditions for algal growth, seasonal variations in the algal flora and an introduction to algal morphology and biology. Then separate chapters on the three different groups, red, brown and green alga follow, with notes on systematics, types and nomenclature rules.  A short chapter of the use of algae as food is also included. There is a special section that covers how to collect and preserve alga for herbarium and microscopic collections. Strangely enough – both volumes contain this same introduction chapter (page 13 – 41), even though the two volumes are not sold separately.


Both volumes contain a scientific text, photos and drawings of both general appearance and microscopic details of all the different species, a valuable tool in identification process. The text covers a general description of the species, morphology, reproduction, seasonal variation, where the species grows and references to literature. The authors have chosen to follow a somewhat different systematic approach that the more commonly used in  This may also be the reason for some differences in names on algae like Callophyllis laciniata is Metacallophyllis laciniata and Polysiphonia elongata is Carradoniella elongata in However, name changes happen so fast these days that it is hard to keep up with the most recent. The number of microscopic photos is nothing but impressive, however, a few are unfortunately not of the best quality. This could also have something to do with the paper the books are printed on, which may not give the best resolution of the photos. Dichotomous keys to genus level are provided after each of the three major groups, and in the presentation of the larger genera also keys to species level. In Volume 2 a glossary of terms used in the text is included. In both books there is an index that covers both volumes.


Both volumes have been tried out on Master students in marine botany working with identification of macroalgae. They are in particular happy with the many photos, of both habitus of the algae and the fine structure such as cross sections and fertile structures. In addition, they point out that the text to each species is very informative.


This is nothing but a very valuable set of two books that is highly recommended for naturalists, students, teachers, professors, or others that are working with or have interest in marine macroalgae. Since the books are in Danish, they will have a limited distribution, mostly to the three Scandinavian countries. However, with the large number of color photographs, many other could benefit from these books by Ruth Nielsen and Steffen Lundsteen. And the price: 500 Danish Kr for 874 pages of is nothing but a scoop!