The Cannabaceae family of plants includes hops,[1] but with respect to cannabis there is some taxonomic classification controversy[2] as to whether Sativa, Indica and Ruderalis are separate species, subspecies or varieties of the same species[3]. Since humans have used cannabis for thousands of years[4] for food, fiber and medicine, cross breeding whether in nature accidently with migration patterns of early man or more recently and deliberately by cultivators, have certainly muddied the nomenclature waters. However, whether you call them separate species or just separate varieties by using leaf variations[5] there are specific morphological differences we can see between Cannabis Sativa, Indica and Ruderalis.

First let’s discuss their similarities with respect to common leaf morphology and anatomy that most plants share and need for the critical function of photosynthesis[6]. Photosynthesis is a critical part of the environment’s cycle of carbon and oxygen. Leaves absorb solar energy from sunlight (or light) and convert it to needed carbohydrates via carbon dioxide fixation to provide the chemical energy needed to grow and flower.  The basic morphologic parts of most leaves contain the flat part called the blade with veins running through it, connecting to the petiole (the stem of the leaf) and sometimes stipules at the base of the petiole.

Looking microscopically at the leaf tissue[7], the outer layer epidermis can have a waxy cuticle with guard cells that control the stoma allowing for gas exchange. The middle layer of tissue is made up of a palisade mesophyll and spongy mesophyll. Chloroplasts are the organelles responsible for photosynthesis and are usually found in the palisades layer. They have a light absorbing pigment, called chlorophyll, which uses a magnesium porphyrin ring to capture sunlight energy. Below the palisades layer is spongy mesophyll which carries much of the vasculature for the plant. The vascular tissue in plants is called xylem and phloem which allows water and nutrients to be carried to all parts of the plant.

As stated above these three plants can be distinguished via leaf morphology. Cannabis sativa is also called narrow leaf drug (NLD) biotype[8] because it has narrow pointy leaves with no pattern on them and described as lighter green. It is known to grow naturally in tropical regions such as Mexico, Cambodia and Thailand. This is the tallest of cannabis plants reaching up to 8-12 feet in height and is somewhat slender. It is described as having a spicy fruity sweet smell created by their terpenes metabolites and supposedly creates a euphoric high that is energy boosting.

Cannabis indica is referred to as wide leaf drug (WLD) biotype[9] due to its broad roundish leaves with a marble-like pattern on them. These plants originated in Asian countries, around Tibet and Afghanistan. They have dense bushy foliage and are shorter, usually not more than 3-6 feet in height.  Their leaves are described as bluish-green hue that can look purple sometimes. They are also known for high quality hash and keif with higher THC content, supposedly causing a hypnotic relaxing high. This cannabis indica plant smell is described as skunky.

Cannabis ruderalis was once thought to be an ancestor of modern cannabis[10]  but now is believed to be a hardy wild growing plant that is possibly another species or subspecies.  The name comes from a botanical term “ruderal” which classifies plants that are the first to seed and take hold after natural or man-made land disruption, thriving in poor or harsh environments.  It is believed to have originated in colder climates of Russia and central Asia, near the Himalayas. It tends to have smaller thick leaves with fewer palmate lobes than Indica or Sativa. Additionally, the plant has less side branches exposing more of the stalk, which is very fibrous and suitable for textiles.  It is smaller in height that even Indica reaching only about 2-3 feet. It known for lower levels of THC and higher levels of CBD as well as other secondary metabolites that tend to make it very pest resistant. [11]  Another interesting feature of this plant is that it flowers according to its age, as opposed to length of sunlight exposure (photoperiodism).This is called auto-flowering[12]  which is a desirable trait for cultivators to use for cross breeding and hybridization.

Today most strains of cannabis are hybrids of these three varieties giving even less credence to their distinctions. Whether these are separate species or varieties of the same species, it is as Shakespeare said, in Romeo and Juliet, “A rose by any other name would smell as sweet.”

[1] Russo E., The case for the entourage effect and conventional breeding of clinical cannabis: No strain no gain. Front Plant Sci. 2018; 9: 1969-1983.

[2] McPartland M., and Guy G., Models of cannabis taxonomy, cultural bias, and conflicts between scientific and vernacular names. Bot. Rev. 2017; 83: 327–381.

[3] Piomelli D., Russo E., 2016) The Cannabis sativa versus Cannabis indica debate: an interview with Ethan Russo, MD.  Cannabis and Cannabinoid Research 2016; 1(1): 44–46.

[4] Meng R., Tang Z., Wu X., et. al. The origins of cannabis smoking: Chemical residue evidence from the first millennium BCE in Parmirs. Sci Adv 2019; 5(6): 1391-1399.

[5] Anderson L., Leaf variations among cannabis species from a controlled garden. Botanical Museum Leaflets, Harvard University. 1980; 28(1) :61-69

[6] Welkie G., Caldwell M., Leaf anatomy of species in some dicotyledon families as related to C3 and C4 pathways of carbon fixation. Can J Bot. 1970; 48(12): 2135-2146

[7] Welkie G., Caldwell M., Leaf anatomy of species in some dicotyledon families as related to C3 and C4 pathways of carbon fixation. Can J Bot. 1970; 48(12): 2135-2146

[8] McPartland M., Cannabis sativa and cannabis indica vs “sativa” and “indica”. In: El Sohly M., Chandra S., Lata H., ed. Cannabis Sativa L-Botany and Biotechnology. Cham. Switzerland: Springer; 2017: 101-121

[9] McPartland M., Cannabis sativa and cannabis indica vs “sativa” and “indica”. In: El Sohly M., Chandra S., Lata H., ed. Cannabis Sativa L-Botany and Biotechnology. Cham. Switzerland: Springer; 2017: 101-121

[10] Hillig, K.W. Genetic evidence for speciation in Cannabis (Cannabaceae). Genet Resour Crop Evol. 2005; 52: 161–180.

[11] Beutler A., Marderosian H., Chemotaxonomy of Cannabis I. Crossbreeding between Cannabis sativa and C. ruderalis, with analysis of cannabinoid content. Econ Bot 1978; 32: 387-399.

[12] McPartland M., Guy W., Models of Cannabis Taxonomy, Cultural Bias, and Conflicts between Scientific and Vernacular Names. Bot. Rev. 2017; 83: 327–381

Dr. Leigh Vinocur is a board certified emergency physician, who also has a cannabis consulting practice for patients and industry. She is a member of the Society of Cannabis Clinicians. And in the inaugural class for the first Masters of Science in the country in Cannabis Science and Therapeutics at the University of Maryland School of Pharmacy.   

This blog is not written or edited by Hearst. The authors are solely responsible for the content.