Cannabis sativa has been employed for thousands of years, primarily as a source of a stem fiber (both the plant and the fiber termed "hemp") and a resinous intoxicant (the plant and its drug preparations commonly termed "marijuana"). Studies of relationships among various groups of domesticated forms of the species and wildgrowing plants have led to conflicting evolutionary interpretations and different classifications, including splitting C. sativa into several alleged species. This review examines the evolving ways Cannabis has been used from ancient times to the present, and how human selection has altered the morphology, chemistry, distribution and ecology of domesticated forms by comparison with related wild plants. Special attention is given to classification, since this has been extremely contentious, and is a key to understanding, exploiting and controlling the plant. Differences that have been used to recognize cultivated groups within Cannabis are the results of disruptive selection for characteristics selected by humans. Wild-growing plants, insofar as has been determined, are either escapes from domesticated forms or the results of thousands of years of widespread genetic exchange with domesticated plants, making it impossible to determine if unaltered primeval or ancestral populations still exist. The conflicting approaches to classifying and naming plants with such interacting domesticated and wild forms are examined. It is recommended that Cannabis sativa be recognized as a single species, within which there is a narcotic subspecies with both domesticated and ruderal varieties, and similarly a non-narcotic subspecies with both domesticated and ruderal varieties. An alternative approach consistent with the international code of nomenclature for cultivated plants is proposed, recognizing six groups: two composed of essentially non-narcotic fiber and oilseed cultivars as well as an additional group composed of their hybrids; and two composed of narcotic strains as well as an additional group composed of their hybrids.

Summary Variation in Cannabis is evaluated in the context of the confusing systematic history of this genus. Aside from some experimentally produced polyploids, all Cannabis is diploid (n = 10), and there appear to be no barriers to successful hybridization within the genus. The present pattern of variation is due in large part to the influence of man. Two widespread classes of plant are discernible: a group of generally northern plants of relatively limited intoxicant potential, influenced particularly by selection for fibre and oil agronomic qualities, and a group of generally southern plants of considerable intoxicant potential, influenced particularly by selection for inebriant qualities. These two groups are treated respectively as subsp. sativa and indica, of C. sativa, the only species of the genus Cannabis. Within each subspecies two parallel phases are recognizable. The “wild” (weedy, naturalized or indigenous) phase is more or less distinguishable from the domesticated (cultivated or spontaneous) phase by means of an adaptive syndrome of fruit characteristics. The resulting four discernible groups are recognized as varieties.

Fifteen species growing in a raised sphagnum peat bog were compared with 13 non-bog species with respect to their light-saturated net photosynthetic rate, and the content of N, P, and K within their foliage and leaf litter. Bog species were found to reabsorb significantly more nitrogen from their foliage preceding leaf fall than non-bog species. An estimate of the potential photosynthate which the species could manufacture during the time a given unit of nitrogen remained in the plant, before being lost through leaf fall, was calculated for the 28 species. The values found averaged 235% higher for the bog evergreens than for the bog deciduous species, and about 60% higher in the bog deciduous species than in the non-bog deciduous species. The hypothesis is advanced that the increased time available to use nitrogen photosynthetically before it is recycled is adaptive in bog plants, especially in evergreens, because of the difficulty in acquiring nitrogen from the extremely nutrient-deficient bog substrate.

Most of the Western World banned the cultivation of Cannabis sativa in the early 20th century because biotypes high in ∆9-tetrahydrocannabinol (THC, the principal intoxicant cannabinoid) are the source of marijuana. Nevertheless, since 1990, dozens of countries have authorized the licensed growth and processing of “industrial hemp” (cultivars with quite low levels of THC). Canada has concentrated on hemp oilseed production, and very recently, Europe changed its emphasis from fiber to oilseed. The USA, historically a major hemp producer, appears on the verge of reintroducing industrial hemp production. This presentation provides updates on various agricultural, scientific, social, and political considerations that impact the commercial hemp industry in the United States and Canada. The most promising scenario for the hemp industry in North America is a continuing focus on oilseed production, as well as cannabidiol (CBD), the principal non-intoxicant cannabinoid considered by many to have substantial medical potential, and currently in great demand as a pharmaceutical. Future success of the industrial hemp industry in North America is heavily dependent on the breeding of more productive oilseed cultivars, the continued development of consumer goods, reasonable but not overly restrictive regulations, and discouragement of overproduction associated with unrealistic enthusiasm. Changing attitudes have generated an unprecedented demand for the cannabis plant and its products, resulting in urgent needs for new legislative, regulatory, and business frameworks, as well as scientific, technological, and agricultural research.

SMALL, E., and JOMPHE, M. 1989. A synopsis of the genus Medicago (Leguminosae). Can. J . Bot. 67: 3260-3294.The genus Medicago has recently undergone extensive taxonomic changes. At least two dozen species not previously accepted as belonging to it have been added. Moreover, the circumscription, infraspecific taxonomy, and nomenclature of many of the species placed in Medicago have been altered recently, and the circumscription and nomenclature of the sections of the genus have also changed. Adding to the need for a synopsis is the fact that many of the species are very difficult to identify. This conspectus presents a key to the 12 sections and eight subsections of the genus, a comprehensive illustrated key to the 83 species (and 18 infraspecific taxa) of Medicago, and brief notes on their geography, ecology, and possible confusion with similar species. SMALL, E., et JOMPHE, M. 1989. A synopsis of the genus Medicago (Leguminosae). Can. J . Bot. 67 : 3260-3294. Le genre Medicago a rtcemment subi d'importants changements taxinomiques. Au moins deux douzaines d'esptces non reconnues comme en faisant partie ont t t t ajouttes au genre. De plus, la circonscription, la taxinomie infrasptcifique et la nomenclature de plusieurs esptces plactes dans le genre Medicago ont Ct C modifites rtcemment, et la circonscription et la nomenclature des sections du genre ont aussi changt. Le besoin d'une synopsis est d'autant plus aigu que plusieurs esptces sont t r b difficiles i identifier. La prtsente synopsis fournit une clef des 12 sections et huit sous-sections du genre, une clef illustrte compltte des 83 esptces (et 18 taxons infrasptcifiques) du Medicago et de brtves notes sur leur gtographie, leur tcologie et la confusion possible avec des esptces semblables. [Traduit par la revue]The genus Medicago has received extensive systematic treatment in the last decade. This paper summarizes taxonomic changes and provides a comprehensive identification guide. The majority of these changes are based on the publications of E. Small, cited here. Herbarium loans (and the numbers of borrowed specimens), mostly of Medicago but also including allied genera, were provided by the following (standard herbarium abbreviations of Holmgren et al.