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Cannabis: Evolution and Ethnobotany

Cannabis: Evolution and Ethnobotany by Robert C. Clarke and Mark D. Merlin. Berkeley, CA: University of California Press; 2013. Hardcover; 452 pages. ISBN-13: 978-0520270480. $95.00.

The authors of this impressive book are well known to avid followers of cannabis (Cannabaceae) literature. Rob Clarke penned the popular books Marijuana Botany (Ronin Publishing, Inc., 1981) and Hashish! (Red Eye Press, 1998). He also was one of the principals of HortaPharm, the company in Amsterdam responsible for many key advances in selective breeding of novel cannabis chemovars in the 1990s. In the interim, he has extensively traveled the Eurasian continent to document ethnobotanical uses of cannabis as medicine, food, and fiber. Mark Merlin is a professor of botany at the University of Hawaii at Manoa, who wrote Man and Marijuana: Some Aspects of Their Ancient Relationship (Fairleigh Dickinson University Press, 1972), and who is an expert on ancient psychoactive plants as well as the botany of Oceania, as attested by his co-authorship of the excellent Kava: The Pacific Elixir (Healing Arts Press, 1997).

This eminently qualified pair has engaged in an ambitious project to summarize and analyze the voluminous literature from disparate sources on cannabis, and bring to the reader a better understanding of its origins and uses, as well as its relationship with man, its chief exploiter and manipulator. The title accurately conveys the focus of the book. Beyond any controversy, this plant is of great economic, ecological, social, and medical importance. Thus, the subject matter is timely and important. The book is unique in both its profound depth and wide scope.

It begins with a dedication to Richard Evans Schultes, PhD, the eminent Harvard University professor and 20th century Father of Ethnobotany, citing his ideals of ecology and human kinship with plants coupled with a cultural sensitivity to the various peoples under study, and an appreciation for their diverse spirituality and cosmology. This book is aptly written in the same spirit.

Although the book necessarily reviews a wealth of previous sources, it successfully bridges the gaps and suggests new and different ways to integrate the material through well-considered theories and approaches. Through careful documentation of the world’s writings on cannabis, the plant’s archeology, and its countless names in dozens of cultures, the authors are able to synthesize the material through critical analysis. The interested scholar would need to read hundreds of articles and book chapters, many distinctly rare and inaccessible, to attempt to reproduce the material included. The authors’ collective experience in the subject makes them uniquely qualified to interpret the material in a coherent and palatable form. The result is an eminently viable tome that is compelling in its exhaustive treatment of the material, as well as its accuracy. Its length may prove challenging to the casual reader, but will prove essential to the dedicated student of the subject who will find those very qualities attractive and rewarding. It is a worthy successor to, and a notable expansion on, Rubin’s Cannabis and Culture (De Gruyter Mouton, 1975). It will definitely serve well as a reference work; in fact, it is difficult to imagine an equal resource on the subject matter.

The text is extremely well written, and is supplemented by excellent graphic matter, including tables, chronologies, full-color maps, and photography documenting cannabis morphology, the plant as grown in situ, and its use by man, whether as an artisanal raw material, ritual object, or foodstuff.

It is unusual to examine a book of this depth that is not an edited multi-author work. The advantage is a high level of consistency and coherence of the narrative. Inasmuch as I was privileged to see this book in its embryonic stages before acceptance by the University of California Press, I am able to emphasize this point: While a previous version of the manuscript suffered from some redundancy and challenges in its organization, those problems have been gratifyingly resolved. The remaining repetitions and other issues are few. Certain terms are defined in an ongoing fashion, and while this may be helpful to those of us who forget their meaning along the way, an alternative approach would have been to consider addition of a glossary of terms, particularly for the less familiar botanical jargon. While the sections on medical usage are comparatively weaker than the others, this is wholly acceptable given the title, scope, and intended focus of the book. This tome will be a perfect complement to upcoming titles focusing on medicinal usage of cannabis, such as Roger Pertwee’s edited work, Handbook of Cannabis from Oxford University Press, and the cannabis monograph from the American Herbal Pharmacopoeia.

Other controversies will be evident in the book, as the subject of cannabis is never too far from debate. One notable area of contention will be the authors’ viewpoints on cannabis taxonomy, a dialogue that has been ongoing since Linnaeus and Lamarck faced off on the matter in the 18th century. While many geneticists and taxonomists, such as Ernest Small, have championed the concept of a single cannabis species, citing the ability of all strains to interbreed, this criterion is curious to many of us. If sufficient as a sole factor, then one would have to accept that all the hundreds of neotropical Gesneriaceae (African violet family) plants are of one species, as virtually all hybridizations produce fertile seed. Rather, Clarke and Merlin have adopted the view of their mentor, Professor Schultes, in the assignation of multiple species or forms of cannabis. They have concentrated on different origins for morphological variants of cannabis named Putative Ancestor, Narrow-Leaf Hemp, Narrow-Leaf Drug, Broad-Leaf Hemp, and Broad-Leaf Drug, based on chemotaxonomy recently advanced by Karl Hillig1-4 and summarized by this author.5 The species debate will continue in all likelihood, since a true consensus on such matters is always an evanescent goal in the discipline of botany. In the interim, the authors’ formulation presents a practical alternative to classify Cannabis according to geographical origins, chemical contents, morphology, and purpose of use. It remains of paramount importance to avoid the pitfall of assuming chemical attributes or psychotropic effects based merely on plant shape or size inherent in the current “sativa” and “indica” monikers popular on the street.

Numerous additional questions remain. How much have humans affected the evolution of cannabis? Do we need to consider the inverse? Does feral cannabis yet exist in the wild? These and countless other issues are weighed and considered in the text. What will certainly be evident to any reader will be the astounding versatility of this plant, which has been characterized as not only a phytochemical factory with a breathtaking breadth of therapeutic potential, but additionally, a foodstuff in its seed composed of high-quality protein and essential fatty acids, a fiber to clothe and insulate, a bait for fish, and a potential organic herbicide and antibiotic. These uses are examined country by country, and culture by culture.

Ritual and psychoactive use of cannabis is appropriately examined throughout the book, from ancient times onward. While cannabis’ usage as a psychotropic or recreational agent garners most of the headlines, the book devotes well-deserved attention to hemp and its husbandry, examining its use as fiber for clothing and paper. Culinary applications are not forgotten either, as we learn of a triple-use plant from Nepal that is utilized medicinally, for clothing, and whose seed provides a tasty chortney/chutney, the recipe for which was previously published.6

Readers will be fascinated by discussions of how cannabis became a key component of Japanese Shinto rites, but is now distinctly rare in that country due to the insertion of the Taima Torishimari Ho, or Hemp Control Act, into the Japanese constitution after World War II. The threats to this herb have not merely been political, as it also has been the object of research on its eradication via Fusarium oxysporum fungi. Additional topics of interest include the following: hypotheses of cannabis evolution based on patterns of glaciation vs. human peregrinations, the history of hemp and fishing, hemp and hanging, and its usage in the belts worn by sumo wrestling champions. In short, this is a book that guarantees the reader will become a top contender in any cannabis trivia contest.

Cannabis: Evolution and Ethnobotany will appeal to students, scholars, and open-minded policymakers. As a potential undergraduate university textbook, an enlightened instructor and indulgent faculty with abundant backbone would be necessary. It also would be a useful addition to curricula in botany, phytochemistry, pharmacognosy, genetics, medical history, etc. To the graduate student or post-doctoral fellow in these disciplines, it should be required reading. In short, this is a superlative work on a most complex and fascinating botanical subject.

—Ethan Russo, MD Senior Medical Advisor GW Pharmaceuticals Group Wiltshire, UK


  1. Hillig KW. Genetic evidence for speciation in Cannabis (Cannabaceae). Genetic Resources and Crop Evolution. 2005;52:161-80.
  2. Hillig KW. A chemotaxonomic analysis of terpenoid variation in Cannabis. Biochemical Systematics and Ecology. 2004;32:875-91.
  3. Hillig KW. A combined analysis of agronomic traits and allozyme allele frequencies for 69 Cannabis accessions. Journal of Industrial Hemp. 2005;10(1):17-30.
  4. Hillig KW, Mahlberg PG. A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae). American Journal of Botany. 2004;91(6):966-75.
  5. Russo EB. History of Cannabis and its preparations in saga, science and sobriquet. Chemistry & Biodiversity. 2007;4(8):2624-48.
  6. Clarke RC. Traditional Cannabis cultivation in Darchula District, Nepal- seed, resin and textiles. Journal of Industrial Hemp. 2007;12(2):19-42.