Plant Cuttings

Biology of algae, lichens and bryophytes, edited by Burkhard Büdel, Thomas Friedl & Wolfram Beyschlag, 2024. Springer Spektrum Berlin, Heidelberg.

We at Cuttings HQ admire algae (e.g., here, here, and here), are both bowled-over and blown away by bryophytes (e.g., here, here, and here), and like lichens – a lot (e.g., here, and here). So, when we became aware of that trio of amazing botanics being dealt with all together in another place, we had to find out more. Which is why Biology of algae, lichens and bryophytes edited by Burkhard Büdel, Thomas Friedl & Wolfram Beyschlag is here appraised.

What’s it about?

In other words, what’s so important about algae (John Raven & Mario Giordano, 2014) (including blue-green algae, cyanobacteria), lichens, and bryophytes (the unifying term for the assemblage of liverworts, mosses, and hornworts)?

The estimated total number of species within this group of organisms is 290,000, which figure represents about 40% of the total known number of vascular plant species (p. 1 of the book). I.e., from a biodiversity point of view. the book’s subject matter is very important. Furthermore, the global impact of these algae, lichens, and bryophytes is huge, their “net biological oxygen production is more than 50% of the Earth’s annual oxygen release” (p. 1). They quite literally help to animate us. And, they “are of enormous ecological importance as primary producers, occurring in almost all habitats where sufficient light is available to fix carbon by photosynthesis from atmospheric CO₂. Their provision of organically bound carbon fuels terrestrial habitats with energy, an essential prerequisite to enable other forms of life” (p. 1). Without them, this world would look very different – and probably not in a good way. That’s three compelling reasons for devoting a book to these organisms.

The New Cryptogams

Whilst the combined relevance and importance of algae, cyanobacteria, lichens, and bryophytes to the ecology of the planet cannot be denied, there’s another reason why this quartet of widely-diverse lifeforms should be considered together in a single book. That justification rests on the editors’ resuscitation [Ed. – or rejuvenation..?] of an ‘old-fashioned’ botanical term cryptogams, and is set out in detail in Chapter 1. Recognising that originally the cryptogams included all non-animal lifeforms that weren’t seed plants [specifically, algae, blue-green algae (cyanobacteria), fungi and lichens, bryophytes, ferns (Warren Walker et al.) and fern-allies, they propose a new cryptogam category. Accordingly, these new cryptogams “comprise all oxy-phototroph (photoautotrophic) life forms whose capability of performing oxygenic photosynthesis is permanent and who, at the same time, feature a hydro-passive* lifestyle” (p. 4), i.e., algae, blue-green algae (cyanobacteria), lichens, and bryophytes (liverworts, mosses, and hornworts). From the ‘old cryptogam’ group the vascular ferns and fern-allies have been excluded, as have fungi, slime-moulds, and oomycetes.

Whilst this redefining of cryptogams is quite radical and progressive, by harking back to the old days of botany it’s also arguably quite regressive in some respects. However, if such a revision helps to focus attention on these often-overlooked organisms, then such an approach – which is also a pragmatic one – has to be a good thing. It is certainly welcomed by all of us at Cuttings HQ [Ed. – and there’s something satisfying about making a 21^st century link to the long-established, venerable tradition of plant study in ‘dusting-off’ that old term, and ‘giving it a good airing’…]**

About the intended readership

Perhaps the most important thing you need to know about Biology of algae, lichens and bryophytes is that it’s a textbook. As such its goals are to inform and educate its readers. I’m very happy to say that both of those goals have been achieved. However, and although most definitely a textbook, a certain level of prior botanical knowledge is assumed, e.g. in the cyanobacteria chapter we have, “Thylakoids are composed of a double-membrane and carry photosystem I and II with the accessory light harvesting pigments (Figs. 3.5, 3.9, 3.20), the ATP-synthase, the cytochrome complex, and the NDH1-complex” (p. 34). Arguably, to get the best out of this information you will need some prior knowledge of the chloroplast, its ultrastructure, and light-harvesting capability, and some understanding of aspects of the photobiology and biochemistry of photosynthesis. That, and the fact that the text is quite a challenging read, leads me to suggest that this textbook is best suited to advanced undergraduates and post-graduates rather than first year students (or those taking general biology courses). Acknowledging that not all education takes place in a formal setting, this book should also be of interest to all who have a deep interest in algae, lichens, and/or bryophytes. From an educational perspective, topic coverage in Biology of algae, lichens and bryophytes includes taxonomy (and there is a lot of taxonomy and evolution), anatomy, structure-and-function, physiology., biochemistry, ecology, and reproduction for the various groups of organisms within the new cryptogams.

About the text

Generally, the text is very well-written (but do note use of American spelling). However, in a few places the phrasing – presumably a consequence of translation from the original German text? – reads a little awkwardly, e.g., “There is a need for a handsome [an unusual word?] term that describes all oxy-phototroph (photoautotroph) life forms…” (p. 2); “Indeed, different analyses recover [I’m not sure what the best substitute word is here, but ‘recover’ reads rather oddly] that it might have been a filamentous, nitrogen-fixing cyanobacterium or that it was a unicellular one” (p. 13); and “The large amount of genomic data that have been accumulated in the last decade has also allowed exploring endosymbiosis and its evolutionary consequences” (p. 277). Whilst these examples aren’t major flaws, they do interrupt the narrative flow as one tries to concentrate on the information being shared by the writers – and with quite a challenging text one does need to concentrate.

About the images

This book is abundantly illustrated – with lots of colourful artwork (by scientific artist Frederick Spindler) and photomicrographs (with appropriate scale bars – which is always nice to see). Images are essential to representing the numerous lifeforms considered in the text, and are particularly useful for showing ultrastructural features and evolutionary relationships between the various groups of cryptogams. Illustrations therefore complement the text, and help deliver its educational goal. But, do note Fig. 3.16 (p. 42), whose panels a and b – side-by-side different microscope views of, ostensibly, the same field of view – are not well-aligned, so matching up the features of note is a little cumbersome.

About the authors

The three individuals named as editors – Burkhard Büdel, Thomas Friedl & Wolfram Beyschlag – are variously credited with (co-)authorship of various chapters, as befits the many years of combined study of – and teaching about – the various groups represented by the new cryptogams. However, in several instances the text is apparently supplied  by the participation of several different or additional authors, e.g. Section 4.2 Chloroplastida—Green Algae, we have Frederik Leliaert, Olivier De Clerck, Tatyana Darienko, Jan de Vries & Thomas Friedl; and Section 5.2 Dinoflagellates is penned by Thomas Friedl & Mona Hoppenrath. Those multi-author contributions contrast with Chapter 6 Symbioses, which appears to have been written solely by editor Burkhard Büdel. Use of authors additional to the editors helps to ensure that the book’s information is provided by the most appropriate experts, and contributes to the book’s solid pedagogic aspirations and credentials.

As the editors acknowledge, “Writing a new textbook about algae, lichens, and bryophytes is a challenge” (p. v). Although the editors pay tribute to their co-authors in the Prolog (p. v), it seems entirely appropriate to give them a mention here as well. So, this reviewer would also like to thank Tatyana Darienko, Olivier De Clerck, Jan de Vries, Louis Graf, Kerstin Hoef-Emden, Mona Hoppenrath, Frederik Leliaert & Angelika Preisfeld, for helping to make Biology of algae, lichens and bryophytes the textbook that it is.

About the contents

Chap 1 Introduction: The New Cryptogams: in which the old-fashioned term ‘cryptogam’ is reimagined for the 21^st century and defined as “the non-vascular oxygenic photoautotrophs (oxy-phototrophs), which comprise algae, cyanobacteria, lichens, and bryophytes” (p. 1), and sets the scene for what follows in the rest of the book.

Chap 2 Endosymbioses: Origin and Diversity of Photosynthetic Eukaryotes and Their General Genetic Exchange Modes: an important overview of the role of endosymbiosis for the acquisition of mitochondria and plastids by ancient unicellular organisms that gave rise to the diversity of the book’s new cryptogams.

Chap 3 Cyanobacteria/Blue-Green Algae: provides a very full account of the general biology of the cyanobacteria, in which the 21.5 pages of the ecology section was a particularly good read.

Chap 4 Algae from Primary Endosymbioses: primarily deals with red and green algae, which latter group as part of the Chloroplastida is importantly the link between algae and land plants (the embryophytes, represented in this book by the bryophytes).

Chap 5 Algae from Secondary Endosymbiosis: which includes brown algae and diatoms (both in the Heterokontophyta), dinoflagellates, coccolithophores, and euglenids.

Chap 6 Symbioses: which deals with both the wide range of ‘algal symbioses’ (e.g. cyanobacteria with Azolla, gymnosperms, and angiosperms; and algae with invertebrates), and lichens [appropriately, the bulk of this chapter deals with lichens].

Chap 7 Bryophytes: liverworts, mosses (predominantly this group), and hornworts.

Glossary: 8.5 pages of terms, from ‘Akinetes’ to ‘Zooxanthellae’, to help the reader understand the text. But, and underlining my point above about the book’s intended readership and their prior knowledge,there are no entries for photosystems, ATP-synthase, cytochrome complex, accessory light harvesting pigments, or the NDH1-complex.

Index: From ‘A-Cyanobacteria’ to ‘Zygotospores’, 47.5, 2-columned pages. Whilst it contains names of taxa and terms relating to ecology, structure, physiology, etc., it appears to be entirely devoid of names of people [many of whom are mentioned in-text, especially when giving background to the history of various topics].

About its up-to-dateness

The editors advise us that “We are aware that the presentation of such a diverse group of organisms in a textbook will always suffer from never being able to meet the latest outcomes of research” (pp. 7/8). Given the time it takes to produce and publish a textbook [for instance, we are told that “The manuscript for this book was prepared over a period of four years” (p. v)] and the often limited opportunity to incorporate newly-published research into the text during that period, there is usually an inevitable ‘mismatch’ between how up-to-date the text can be. [Ed. – by way of example, reviewing this 2024-published book in April 2025 it won’t have been able to include the work of Che-Chih Chen et al. (2025) on the ‘phyllosymbium’. And which is one reasons why subscribing to sites such as plantcuttings.uk [https://plantcuttings.uk/] will help those interested in such botanical topics to keep more up-to-date whilst awaiting revised editions of the textbook…]. With that caveat, how up-to-date is Biology of algae, lichens and bryophytes?

Noting that the book’s Prolog was dated February 2023 I wasn’t expecting any sources cited in the book to be dated more recently than that. However, the book does cite “Guiry 2024” on page 2. And it also cites two sources for 2023, Guiry and Guiry (2023) (p. 116), and Vranken et al. 2023 (in a footnote at the bottom of p. 107)***. I also noted 22 sources cited for 2022. Which certainly suggests to me that the book is probably as up-to-date as one can expect it to be. In any event, the editors’ “focus is to present an overview of the stunning variety of oxy-phototroph (photoautotrophic) species” (p. 8). And, “This book is meant as an invitation to become aware of the fascinating diversity developed in amazing evolutionary processes over the history of life” (p. 8). On both counts, Biology of algae, lichens and bryophytes does what it intended to.

About its sources

Unlike many botany textbooks that present information but without necessarily stating its source, Biology of algae, lichens and bryophytes goes to considerable lengths to provide the evidence for the statements made. It’s not perfect and in some places it would be useful to have appropriate sources shown to allow interested readers to follow-up the fact(s) stated, but it is most refreshing to see a textbook that is so well-referenced. That can only be a good incentive – and reminder – to student readers to ensure their own written work is as well-sourced. In-text references are abundant and cited by author and date. Full citation details for a chapter’s references are grouped together at the end of the relevant chapter. And the references supplied are numerous – e.g., approx. eight, 2-columned pages re Chapter 3 Cyanobacteria, 23.5 pages for Chapter 7 Bryophytes, and 30.5 pages for Chapter 5, Algae from secondary endosymbiosis. There is no separate listing of useful, supplementary reading, although mention is often made within a chapter to suitable texts that give more information about a particular topic. In the interests of pointing readers in the direction of supplementary reading about lichens and mosses, I’m very happy to mention Elizabreth Lawson’s Moss and lichen.

About its accuracy

Whilst this general botanical reviewer is unable to pass comment on the great deal of specialist factual information presented in the book, some items did catch my eye and need to be mentioned. For example, here are several matters of typographical concern. Part of the legend to Fig. 2.6, states “resulted in the spread of rhodophyte (read [presumably, red was intended] algal)-derived plastids”… (p. 15); “Particularly, the cell size reduction with each generation was explained independently (MacDonald 1869; Pfitzer 1869), complimenting [this should be complementing?] the earlier discovery of the size restoration (Thwaites 1847)” (p. 249); and “The complex thalloid liverworts are either dioicous or monoicous [I don’t recognise either of these terms/spellings, and neither appear in the Glossary] (Bischler 1998). In monoecious [this spelling I do recognise, but it’s inconsistently applied in the text] species,” (p. 484). [Ed. – very much related to this matter, a footnote on p. 107 states: “Monoecious/dioecious [which terms are absent from the Glossary] is the correct terminology given that the sex is determined in the haploid phase (see Vranken et al. 2023)”. Which emphasises the need for consistency of terminology/spelling throughout the text].

All such items are easily corrected – where necessary – in subsequent printings or editions of what seems destined to be the standard cryptogamic botany text for many years.

Summary

Biology of algae, lichens and bryophytes edited by Burkhard Büdel, Thomas Friedl & Wolfram Beyschlag is a most impressive textbook delivering up-to-date, evidence-based information about its subject matter. It deserves to be widely used by educators and their students, and all those interested in finding out more about these fascinating photosynthetic lifeforms.

* “Hydro-passivity includes dependence on water to keep the shape of bodies or cells while exhibiting the full range from desiccation sensitivity to desiccation tolerance” (p. 4). And, “Hydro-passive: Water uptake and loss is a passive process and happens to the organism depending on the availability in their environment and climatic conditions (e.g. air humidity, temperature, dew point, water vapour deficit)” (from the book’s Glossary, p. 608), The concept is further explained and expanded on page 6 of the book.

** Wisely, from a book marketing and sales point of view, The biology of the new cryptogams wasn’t used as the title for this book (although it could be considered its unofficial sub-title). Referring to algae, lichens and bryophytes in the title, i.e., in using terms that should be much more familiar to potential readers, is a ‘much safer bet’. And calling it The biology of the non-vascular oxygenic photoautotrophs would probably have been worse…

*** Although the latter instance is somewhat overshadowed by the fact that I couldn’t find details of the Vranken et al. 2023 reference in the book. I did find two Vranken et al. references listed (on p. 216 – where I’d expect Vranken et al., 2023 to be), but they were for 2013 and 2018. I’m therefore left wondering if mention of Vranken et al., 2023 in-text was an error. Maybe it was a typo for Vranken et al., 2013? Or Vranken et al., 2013 is a typo for Vranken et al., 2023..? Or there is indeed a Vranken et al. 2023 reference but it was omitted from the list of references on p. 216. Anyway, something to get sorted in a future version of the book.

REFERENCES

Che-Chih Chen et al., 2025. A thallus-forming N-fixing fungus-cyanobacterium symbiosis from subtropical forests. Sci. Adv. 11(7): eadt4093; doi: 10.1126/sciadv.adt4093

“Guiry MD (2024) How many species of algae are there? A reprise. Four kingdoms, 14 phyla, 63 classes and still growing. J Phycol 60. https://doi.org/10.1111/jpy.13431“ [from the book’s list of references on p. 8]

“Guiry MD, Guiry GM (2023) AlgaeBase. World-wide electronic publication. National University of Ireland, Galway. http://www.algaebase.org. Accessed 14 Feb 2023]” [from the book’s list of references on p. 210]

John A Raven & Mario Giordano, 2014. Algae. Current Biology 24(13): R590-R595; https://doi.org/10.1016/j.cub.2014.05.039

“Vranken S, Bosch S, Peña V, Leliaert F, Mineur F, De Clerck O (2018) A risk assessment of aquarium trade introductions of seaweed in European waters. Biol Invas 20:1171–1187” [from the book’s list of references on p. 216]

“Vranken S, Robuchon M, Dekeyzer S, Bárbara I, Bartsch I, Blanfuné A, Boudouresque CF, Decock W, Destombe C, de Reviers B, Díaz-Tapia P (2013) AlgaeTraits: a trait database for (European) seaweeds. Earth Syst Sci Data15(7):2711–2754” [from the book’s list of references on p. 216]