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Abscisic Acid

Abscisic acid is a hormone in plants produced as a stress response, especially to drought, that promotes stomatal closure to minimize water loss and regulate various growth and developmental processes.


Acclimatization, also referred to as “hardening off,” is the process of gradually adjusting a tissue culture explant from a high-humidity, non-photosynthetic environment to a lower-humidity, photosynthetic environment. 

Adaptation (Genetic)

Adaptation refers to the process of an organism gradually changing genetically to better survive and reproduce in its environment.

Adaptation (Taste)

Taste adaptation occurs with repeated exposure to a specific flavor or aroma and increases acceptance or decreased perception of its intensity.


Aeroponics is a cultivation technique in which plants are suspended in air, and the roots are misted with a nutrient-rich water solution.


Agar is a gelatinous substance derived from seaweed and used as a solid medium in tissue culture to support the growth of plant cells.


An allele is one or more alternative forms of a gene that can occupy the same locus on a chromosome.


Androgenesis is the development of plants exclusively from male sex cells, propagating plants genetically identical to the male parent to preserve and amplify specific desired traits.


Anemophilous plants rely on wind for pollen dispersal.


An annual plant completes its entire life cycle, from germination or clone to the production of seeds, within one growing season and then dies. See Biennial and Perennial


An anther is a cluster of pollen sacs that grow on male cannabis plants.

Apical Dome

The apical dome is the absolute tip of the meristem and consists of only a tiny cluster of undifferentiated meristematic cells. The apical dome has no leaf primordia and is unattached to the vascular system.

Apical Dominance

Apical dominance is when the main, central stem (apical meristem) grows more predominantly than the side branches, suppressing their growth and optimizing exposure to light and other resources.


Apomixis is a rare occurrence with asexual reproduction that bypasses the typical fertilization process, allowing the plant to produce seeds that are genetically identical to the parent plant without the fusion of gametes.

Aseptic Culture

Aseptic culture is the growth of cells, tissues, or organs in a sterile environment that is free from any contaminants, which ensures pure and uncontaminated development. However, no culture with living plants is truly “sterile.”

Aseptic Technique

Aseptic technique is a set of practices and procedures that maintain a sterile and contamination-free environment during tissue culture work, including using sterile instruments, clean surfaces, and proper handling.


The autoclave is a critical piece of lab equipment that uses high temperatures and steam to sterilize all the media, water, and glassware. 


Autoflower, or day-neutral plants, automatically transition into the flowering stage based on time rather than photoperiod. The autoflowering trait is associated with Cannabis ruderalis plants. 


Auxins are a class of plant hormones that are crucial for growth regulation and involved in various physiological processes such as cell elongation, division, and differentiation.


Backcross (BX)

A backcross is a breeding technique where a plant is crossed back to one of its parents to reinforce specific traits.

Bag Seed

Bag seeds are those that are found in a bag of cannabis flower and typically result from accidental pollination or hermaphroditic development.

Base Pair

A base pair is a pair of encoded proteins at a single site of DNA.


A biennial plant requires two years to complete its life cycle, typically growing vegetative structures and storing energy in the first year and then flowering, producing seeds, and dying in the second year. Examples include carrots, celery, and parsley. See Annual and Perennial.


Biosynthesis is the process by which plants create complex substances essential for growth and survival.


A bract is a small structure enclosing the cannabis plant’s reproductive parts, specifically the female flower’s seed pod. Cannabinoids and terpenes are highly concentrated on bracts, making them primary sites for trichome production.

Broad Leaf Drug Varieties

Broad leaf drug varieties have broader leaflets and are often associated with indica-dominant cultivars that are thought to produce relaxing and sedating effects.

Bro Science

“Bro science” is a slang term used in the cannabis industry that refers to unverified, anecdotal advice or information, typically based on personal experiences or opinions, that are not supported by science.

Bubble Hash

Bubble hash is a slang term for water hash. It refers to the bubbles made in the mixing process, the high-quality hash bubbles produced when smoked, and the company Bubble Bags, which popularized a water hash bag filtering system.

Bulk Selection

Bulk selection is a breeding method that involves selecting and intercrossing multiple individuals from a population without identifying specific parent plants to improve the overall genetic diversity and performance of the population.


See Backcross



The callus is an undifferentiated mass of cells that can be induced to regenerate into new tissues or organs, often used in tissue culture techniques.

Callus culture

Callus culture is a tissue culture technique that involves the cultivation and regeneration of undifferentiated callus tissue, which can then be induced to develop into shoots or roots.

Calvin Cycle

The Calvin Cycle is a series of biochemical reactions occurring in the chloroplasts during photosynthesis, where atmospheric carbon dioxide is converted into glucose, providing the energy and structural components necessary for growth and development.


Calyx cells are part of the perianth of the female flower and form a nearly transparent, delicate tissue that partially encloses the ovule. Contrary to common use in the industry, there is no defined calyx structure in the female cannabis flowers, and the term is incorrectly used to identify the bract.


Cannabinoids are a group of chemical compounds produced by animals and plants. All animals, including humans, have an endocannabinoid system that produces endogenous cannabinoids to promote homeostasis, or balance of internal systems. Plants produce phytocannabinoids that interact similarly with the endocannabinoid system when ingested by animals. 

Cellular Respiration

See Respiration


Chaff is the plant material, specifically the bract and other foliage that protects the seed, that is typically separated during processing.


Chemotype, also called chemovar, refers to the chemical profile or composition of cannabinoids, terpenes, and other phytochemicals found in a cannabis plant, which determines its potential effects and therapeutic properties.


See Chemotype


Chlorophyll is a green pigment in the chloroplasts that absorbs light energy and converts it into chemical energy through photosynthesis.


Chloroplasts are components that perform photosynthesis, turning light, water, and carbon dioxide into energy for growth.


A chromosome is a DNA structure that carries genetic information.

Chromosomal Rearrangement

Chromosomal rearrangements in plants are alterations like translocations, inversions, deletions, and duplications. 

Clonal Generations

The term clonal generations refers to subsequent batches of clones derived from the original plant or its clone descendants.


A clone is a genetically identical copy of a parent plant produced by asexual reproduction, such as cloning or tissue culture. 


A cola is a cluster of flowers found at the top of the main stem or branches. “Cola” means tail in Spanish and refers to the shape of the flower cluster. 

Complex Polyhybrids

A complex polyhybrid has been bred from diverse parents over many generations.


The cotyledon is the embryonic leaf that emerges during seed germination.


The term “cross” is used to name and identify the lineage of a cultivar before the cultivar is named. Unlike cultivar, it is non-specific because it can refer to all the progeny of a single crossbred generation. Crosses are usually denoted by the mother receiver’s name first and then the donor’s name second. For instance, Skunk #1 (♀) x OG Kush (♂). 


Crossbreeding is the deliberate mating of two different cannabis cultivars or varieties to create offspring with desired traits. 


Cross-pollination is the transfer of pollen from the male reproductive organs of one cannabis plant to the female reproductive organs of another, resulting in hybrid offspring.


Cryopreservation preserves living cells or tissues at extremely low temperatures, typically using liquid nitrogen, to maintain long-term viability.


A cryoprotectant is a substance added to cells or tissues prior to cryopreservation to protect them from freezing-induced damage, typically by reducing ice formation and cellular dehydration.


A cultivar is a plant that has been selectively bred for specific characteristics, such as potency, flavor, or growth pattern and is cultivated to maintain these desired traits.


Curing is post-harvest drying and aging of cannabis flowers in a controlled environment to enhance flavor, aroma, and overall quality.


Cut-fishing is a term used to describe knowingly sharing or selling a clone while deceptively altering its name. It is analogous to “catfishing” or using a fake online identity to deceive others.  


Cytokinins are a class of plant growth substances (phytohormones) that play a crucial role in cell division, growth, and development, impacting processes such as flower development and branching.



See Autoflower


Decarboxylation is the process of an acid cannabinoid, like THCa, CBDa, CBGa, or CBCa, losing a carboxyl group to become their “active” forms, Δ9-THC, CBD, CBG, or CBC. 


Dedifferentiated cells are capable of growing into a variety of different cell types.


Defoliation is the selective removal of leaves or foliage from a cannabis plant, often done to improve light penetration and airflow and prevent moisture-related issues.


Dioecious plant species have separate male and female individuals, each with specific reproductive roles.


An organism with two complete sets of chromosomes, one inherited from each parent, is a diploid. Cannabis and humans are diploid organisms. See Polyploidy.


A donor is a pollen-producing male or reversed-sex female plant used to fertilize a receiver. 

Double Helix

The structure of DNA consists of two strands that coil around each other, called a double helix.

Dry Trim

Dry trimming is a technique where cannabis flowers are trimmed of excess leaves and foliage after they have been dried and is typically done to preserve resin and trichomes.


Dudding is a condition where plants exhibit stunted growth and reduced potency, often due to a genetic mutation or a viral infection such as hop latent viroid, rendering them less valuable for cultivation and consumption. Dudding symptoms include stunted growth, abnormal branching, brittle stems, trichome reduction, loss of terpenes, loss of cannabinoids, and stunted flower growth.



Embryogenesis is the process of embryo formation and development, which can be induced in tissue culture by manipulating growth factors and hormones.

Embryo Rescue

Embryo rescue is a technique in which embryos from incompatible crosses are cultured in vitro to save them from failure and allow them to develop into viable plants.

Endocannabinoid System (ECS)

The ECS is a complex cell-signaling system in animals, including humans, that interacts with cannabinoids and plays a crucial role in regulating a range of physiological processes, including mood, pain sensation, inflammation, digestion, appetite, and memory. See Cannabinoids

Endogenous Cannabinoids

Endogenous cannabinoids are naturally occurring compounds produced within the bodies of animals, including humans, that interact with cannabinoid receptors.


Endosperm is the nutrient-rich tissue inside the seed that feeds the developing plant embryo during germination.

Ensemble Effect

The ensemble effect is a term analogous to the entourage effect but removes the emphasis implied by using the term “entourage” on one or two primary cannabinoids. See Entourage Effect.

Entourage Effect

The entourage effect is a theory that the effects of cannabis are a result not of one or two isolated compounds but the plant’s diverse compounds working together, amplifying the therapeutic benefits and effects beyond what each compound would do individually. It is alternately referred to as the “ensemble effect.” See Ensemble Effect.


Epigenetics is the study of changes in gene activity in response to an organism’s environment.


Ethylene is a hormone that induces the expression of female sex organs in female cannabis plants.


Evolution is the gradual process of genetic change across generations that shapes the diversity and adaptability of different varieties.


An explant is a small piece of tissue, such as a leaf or stem, taken from a parent plant and used as the starting material for tissue culture.

Ex-Situ Conservation

Ex-situ conservation means protecting plant genetic resources by preserving them outside their natural habitats, like in seed banks or botanical gardens.

Ex vitro

Ex vitro refers to plants that have been acclimated and transitioned from a controlled environment, such as tissue culture, to an external growth environment.


F1, F2, F3, and etc. 

See Filial Generation.

Feral Varieties

Feral varieties are wild, non-cultivated varieties adapted to their environments through natural selection.

Filial Generation

A cross between two distinct parental lines or cultivars and inbreeding within each generation results in a filial generation. The first filial generation is called filial generation 1 (F1). Crossing two F1 siblings results in an F2 generation, which is typically more genetically diverse than the F1 due to the segregation and independent assortment of alleles during gamete formation. Subsequent filial generations are referred to as F3, F4, and so on, as the process of crossing and inbreeding continues. 


FIMming is a slang term for a cultivation technique that involves pinching the top leaves to promote bushy growth. It is a form of high-stress training, which can be stressful on plants but increase yields. According to Royal Queen Seeds, “The word FIM stands for ‘fuck I missed,’ and hints at how sloppy the technique appears.” See High-Stress Training


Flavonoids are pigment compounds responsible for color and flavor that have antioxidant and other properties with therapeutic applications.

Flavorant Compounds

Flavorant compounds such as alcohols, aldehydes, and esters influence the aroma and flavor of cannabis. 

Flowering Stage

The flowering stage is the phase in the cannabis life cycle when the plant starts producing flowers.


Flushing is watering cannabis plants with plain, pH-balanced water to remove excess nutrients and salts from the growing medium before harvest.



A gamete is a reproductive cell of an animal or plant.

Gen-0 Plant

A Gen-0 plant has been directly acclimatized from tissue culture.

Gen-1 Plant

A Gen-1 plant is cut and cloned from a Gen-0 tissue culture plant. When cut with sterilized tools and grown in a clean environment.


A gene is a segment of DNA that dictates the plant’s traits, characteristics, and functions, influencing its structure, metabolism, and environmental responses.

Genetically Modified Organisms (GMO)

GMOs are organisms with DNA alterations that do not occur naturally through mating or natural recombination. 

Genetic Depression

Genetic depression occurs as a result of inbreeding and describes unhealthy plants with a diminished capacity for survival and reproduction. 

Genetic Diversity

Genetic diversity refers to the range of genetic variation present within a population or species, crucial for the long-term health and adaptability of a breeding program.

Genetic Locus (plural: loci) 

A genetic locus is like an address on a street, but in this case, the “street” is the chromosome, and the “address” is the specific location on that chromosome where a particular gene is found.

Genetic Mapping

Genetic mapping is identifying and locating specific genes or markers on a cannabis plant’s chromosomes, enabling breeders to understand the inheritance of traits and facilitate targeted breeding efforts.

Genetic Marker

A genetic marker is a specific DNA sequence or gene variant associated with a particular trait or characteristic used in breeding to identify plants with desired traits.

Genetic Transformation

Genetic transformation is the introduction of new genetic material into an organism’s genome, often done through the use of recombinant DNA technology or gene editing techniques.


A genome is the complete set of genetic material (DNA) in an organism.

Genomic Selection

Genomic selection is a breeding approach that uses large numbers of genetically distinct but closely related individuals grown under identical conditions so that the best combination of alleles for that particular environment are identified and followed using qualitative trait loci and linkage disequilibrium. Essentially, instead of using specific markers, the entire genome is used to identify which plants perform better for the specific conditions.


A genotype is a categorization based on the genetic makeup of an individual, including all the genes and alleles it possesses.

Genotypic Selection

Genotypic selection means choosing plants based on their genetic makeup or specific gene variants associated with desired traits, often using molecular markers.


Germination is the development of a plant from a seed. 


Germplasm is the genetic material or resources, such as seeds, clones, or tissue, that are used to preserve diverse genetics.


Gibberellins are plant hormones that play a crucial role in growth and developmental processes, including stem elongation, germination, and flowering.


Gravitropism is the response that directs roots to grow downward and stems upward in reaction to gravity.


Gynogenesis produces haploids by stimulating eggs to develop into haploid embryos without fertilization.



A haploid is a cell, like pollen or an ovule, with a single set of chromosomes representing the male and female gametes. Cannabis is naturally diploid. See Polyploidy.

Harvest Window

The harvest window is the optimal timeframe during the flowering stage when cannabis plants have reached their peak maturity and cannabinoid content for harvest.


Hash or hashish is the concentrated resin of the cannabis flowers produced by separating trichomes (resin glands) from the plant material and then compressing them.


Varieties bred for their seeds and stalks have traditionally been referred to as “hemp,” while varieties bred for their resinous flowers were referred to as “marijuana.” Hemp and marijuana are the same plant. However, in most parts of the world, “hemp” is arbitrarily defined as a cannabis plant containing less than 0.3% Δ9-THC, and “cannabis” has replaced the use of the politically-charged term “marijuana” to refer to high-THC flowers. Therefore, “cannabis” in this context refers to plant varieties bred for their high-THC resinous flowers, and “hemp” refers to the stalk, flower, or seeds of low-THC plants. 


A hermaphrodite is a plant that develops both male and female reproductive organs, usually as a stress response.


A heterophobic organism relies on external energy sources to grow. Bacteria, fungi, and animals are heterotrophic, but plants typically are not.


Heterosis refers to the phenomenon where hybrid offspring exhibit superior qualities, such as increased growth, vigor, or stress resistance, compared to their parent plants.


A heterozygous organism has two different alleles for a specific gene. Heterozygous offspring inherit one copy of different alleles from each parent organism. 

High-Stress Training (HST)

HST in cannabis cultivation involves using intensive, stress-inducing techniques to strategically manipulate plant growth and boost hormone production, enhancing structural strength and potentially increasing yield through optimized light exposure.


A homozygous organism has two identical alleles for a specific gene. Homozygous offspring inherit one copy of the same allele from each parent organism. 


Hormones are chemical compounds that play essential roles in plant growth and development.


Hemp fiber, called “hurd,” is strong and durable, making it an ideal material for producing rope, clothing, and a sustainable construction material known as “hempcrete.”  


Hybrid refers to the offspring resulting from the crossbreeding of two distinct varieties.

Hybrid Vigor 

See Heterosis.


Hydroponics is a method of cultivation that utilizes soilless substrates such as rockwool, light expanded clay aggregate (LECA), or other inert substrates and precise nutritional feeding delivered through water. 



See Inbred Line.


Inbreeding is mating closely related individuals within a population to stabilize and reinforce desirable traits.

Inbred Line (IBL)

An IBL is a stabilized line achieved through multiple generations of inbreeding, resulting in offspring that are genetically uniform and true-breeding. See Inbreeding


Indica, technically speaking, is considered to be a variety of cannabis plants originating in the Hindu Kush mountain range. 

Induction Phase

The induction phase is when cannabis plants transition from vegetative growth to flower formation.


Inheritance is the genetic transfer of traits from parent plants to their offspring through their genes.

Integrated Pest Management (IPM)

IPM is a holistic approach to managing pests and diseases that utilizes a combination of prevention, monitoring, and intervention strategies.

Intersex Traits

Some cannabis plants have a genetic predisposition to exhibit both male and female reproductive characteristics, often termed “hermaphrodites” or “herms.” Typically, cannabis plants are dioecious, meaning they produce either male or female flowers. Due to genetic factors or environmental stressors like irregular light patterns or chemical imbalances, a plant can develop both male and female flowers on the same individual. Expression can vary from minimal to excessive, and the trait can be bred into or out of a genetic line. This phenomenon is generally undesirable in cannabis cultivation because male flowers can pollinate female flowers, leading to seeded plants.


An intragenic organism’s genome has been artificially altered by introducing genes or DNA sequences from the same species. Theoretically, intragenic plants have a genome that could arise through traditional breeding methods. 


An isomer is a compound with the same molecular formula but a different structural arrangement.

In vitro

In vitro is Latin for “in glass,” referring to processes or experiments conducted in a controlled environment such as a Petri dish.



Plants that adapt to local environments where they are domesticated in isolation from other genetic populations are known as landraces.

Light Manipulation

Indoor and mixed-light cultivators may manipulate light patterns to stress plants or shift their growth stage.


Lollipopping is the practice of removing the lower, less productive branches and foliage of a cannabis plant to focus energy on the upper canopy and improve airflow.



Macronutrients are required in the greatest quantities for plant growth, development, and overall health. Macronutrients are nitrogen (N), phosphorus (P), and potassium (K).

Marker-Assisted Selection (MAS)

MAS is choosing plants to breed with based on identified genetic markers. 


Meiosis is the cell division process that produces four genetically diverse sex cells, each with half the chromosomes of the parent cell.

Mendelian Inheritance

Mendelian inheritance is the transmission of genetic traits from parent plants to offspring according to the laws formulated by Gregor Mendel.

Meristem Culture

Meristem culture is a form of tissue culture starting from meristematic cells.


Methylation is a common epigenetic modification that can affect how genes are expressed, potentially leading to phenotypic changes. See Epigenetics


Micronutrients are required for plant growth, development, and overall health, albeit in smaller quantities than macronutrients. Micronutrients include iron (Fe), manganese (Mn), zinc (Zn), boron (B), copper (Cu), molybdenum (Mo), and chlorine (Cl).

Microorganism Load

Microorganism load refers to the quantity or concentration of microorganisms, such as bacteria, fungi, viruses, and protozoa, present in a given environment, substance, or sample. In various contexts, such as healthcare, the food industry, or scientific research, determining the microorganism load is crucial to assess the level of contamination and the risk of infection or to ensure sterility and safety. For instance, in tissue culture, a high microorganism load would indicate contamination, potentially jeopardizing the viability and purity of the cultured tissues or cells.


Micropropagation is a technique used in tissue culture to rapidly produce large numbers of genetically identical plants. Micropropagation is also known as clonal propagation.


The micropyle is a small opening in the ovule through which the pollen tube enters during fertilization to allow the male sperm cells to reach the female egg cell.


Mitochondria are the cell organelles that produce energy through cellular respiration, powering various metabolic activities crucial for growth and development.

Mixed Light

Mixed light cultivation refers to plants grown in hoop houses using light deprivation techniques or plants grown in greenhouses using the sun and supplemental light and/or light deprivation techniques. 


Mobilization refers to the plant’s ability to move and utilize nutrients, water, and other essential elements for growth and development.


Monoecious plants have both male and female reproductive organs on a single plant. Most plants are monoecious. Cannabis is in the minority of plants that are dioecious. See Dioecious

Monster Cropping

Monster cropping is when the plant simultaneously grows flowers and foliage, reducing yield significantly.

Morphological Characteristics

Morphological characteristics are the individual observable structural features and forms of the plant, such as leaf shape, plant height, and branching patterns.


Morphology is the study of the forms and structure of organisms and their specific structural features, including development patterns.

Mother Blocks

Mother blocks are the donors for aseptic material to multiply in the second stage of tissue culture.


Mutations are the changes in the DNA that can result in varied traits, potentially creating cultivars with distinct properties or behaviors.


Narrow-Leaf Drug Varieties

Narrow-leaf drug varieties have narrower leaflets and are often associated with sativa-dominant cultivars that are thought to produce uplifting and cerebral effects.

Non-Polar Extraction

Non-polar extraction utilizes non-polar solvents like butane or hexane to extract non-polar compounds. 


A nucleotide is the basic building block of DNA and RNA, consisting of a sugar, a phosphate, and a nitrogenous base, which encodes the plant’s genetic information.

Nutrient Deficiency

Nutrient deficiencies are a lack of essential nutrients that leads to visual symptoms and potential growth issues.

Nutrient Solution

Nutrient solutions are mixtures of water and essential mineral nutrients provided to cannabis plants through hydroponic or soilless growing systems.

Nutrient Toxicity

Nutrient toxicity refers to the adverse effects caused by an excess accumulation of certain nutrients, leading to nutrient imbalances and potential damage.


Open Pollination

Open pollinating means allowing plants to be pollinated naturally, either by wind or insects, without controlled breeding or selecting specific parent plants.


Organelles are specialized structures within the cell that perform specific functions, such as energy production in mitochondria or photosynthesis in chloroplasts.


Organogenesis is the process of organ formation and development, which can be induced in tissue culture by manipulating growth factors and hormones.

Orthodox Seeds

Orthodox seeds can survive freezing or drying in ex-situ conservation. See Ex-Situ Conservation.


Overdominance, also known as heterozygote advantage, is a concept in breeding and genetics where the heterozygous genotype confers an advantage or superior trait expression compared to either of the homozygous genotypes. In practical terms, individuals with two different alleles for a specific gene are more robust or healthier than those with two identical alleles. This phenomenon is often observed in cases of genetic diversity and can contribute to the maintenance of genetic variation within a population. A classic example of overdominance is the heterozygous advantage in sickle cell anemia, where individuals with one normal and one sickle cell allele are more resistant to malaria, leading to a survival advantage in regions where malaria is prevalent. See Homozygous and Heterozygous


Overwintering means to survive the winter and refers to seeds lying dormant until germination conditions are met in the spring.



P1 refers to the parental generation or first parental line used in a breeding program.

Parental Selection

Parental selection is the process of choosing specific cannabis plants with desirable traits to serve as parents in a breeding program.


Parthenogenesis is a method to produce haploids that involves the development of the egg without fertilization, producing haploid offspring. See Polyploidy.


Perennial plants live for more than two years, growing and flowering over multiple seasons. See Annual and Biennial


pH is a measurement of the acidity or alkalinity of the growing medium or nutrient solution.


Phenotype is a categorization of organisms based on the observable physical or biochemical characteristics of an individual resulting from the interaction of its genotype with the environment.

Phenotypical Traits

Phenotypical traits are the observable and measurable characteristics of the plant, such as color, shape, size, and resin production, which result from the influence of its genetic makeup and the environment.

Phenotypic Selection

Phenotypic selection means choosing plants based on their observable physical traits, such as height, flower structure, aroma, or resin production.


Phloem is the living tissue in plants that transports nutrients, sugars produced during photosynthesis, and other organic compounds from leaves to stems and flowers.


A photoautotrophic organism uses light, CO2, and water to photosynthesize and create its own energy. Plants are typically photoautotrophic.


Photoperiod refers to the ratio of light to the darkness that a plant is exposed to, which affects its flowering response.


Photoperiodism is the physiological response of cannabis plants to changes in day length, triggering the transition from vegetative growth to flowering.


Photosynthesis is the essential process where plants convert light energy, water, and carbon dioxide into glucose and oxygen to fuel growth and development.


Phototropism is when a plant moves or grows towards the light source to maximize its exposure.


Phyllotaxy is the arrangement or pattern of leaves, flowers, or other plant structures along the stem or axis of a plant. It describes how these structures are positioned with respect to each other. Phyllotaxy can vary among different plant species and is typically categorized into different patterns, such as alternate (where one leaf or structure emerges at each node in a spiral or alternating fashion), opposite (where two leaves or structures arise from the same node, positioned directly across from each other), or whorled (where three or more leaves or structures arise from the same node in a circular arrangement). The specific phyllotaxis pattern of a plant can have ecological and physiological significance.


Phytocannabinoids are a diverse group of chemical compounds produced by cannabis and other plants that interact with animal bodies’ cannabinoid receptors. See Endocannabinoid System.


A pistil is the female plant’s reproductive part, consisting of a sticky stigma to catch pollen and an ovule, where, once fertilized, a seed will develop.

Plant Genetic Resources

Plant genetic resources are valuable genetic materials for breeding, developing diverse cultivars, and conserving species biodiversity.

Plant Growth Regulator (PGR)

Plant growth regulators are either natural or synthetic hormones that are used to alter or control plant growth and are used to affect its size, shape, and flowering.

Polar Extraction

Polar extraction uses a polar solvent such as water or alcohol to extract polar compounds.


Pollen is the male reproductive cells of a plant and is the necessary genetic material for fertilization.

Pollen Chucking

Pollen chucking is the informal, experimental breeding technique where pollen is applied to female plants, usually without controlled or selective breeding and often with no specific intentions, typically resulting in complex polyhybrids with unpredictable and varied offspring. A pollen chucker is a slang term for an amateur breeder.

Pollen Sac

Male cannabis flowers develop pollen sacs or small balls full of pollen that open up to disperse pollen.

Pollination Window

The short period when plants can receive pollen is called the pollination window. In cannabis, the pollination window typically begins around the third week of flowering and continues through the fifth, although optimal pollination is between three and a half to four weeks. The exact timing varies by cultivar.


Polyploidy is a condition in which a plant has more than two sets of chromosomes, which can happen when cells divide incorrectly or when a plant is exposed to radiation or certain chemicals. Polyploidy breeding can overcome non-viability and infertility issues, create seedless cultivars, or enhance traits like resistance to pests or pathogens. See Diploid and Haploid


A population is a group of plants that share common genetic characteristics and are used in breeding programs to introduce and combine desirable traits.

Population Development

Population development refers to systematically selecting and crossbreeding plants over multiple generations to achieve specific desired genetic traits within a larger group.


Progeny are all the offspring resulting from the breeding of parent plants.

Protoplast Fusion

A “protoplast” is a fully functional, living plant cell with the cell wall removed. Protoplast fusion is a type of genetic modification where protoplasts of two different plant species are fused to form a new hybrid with the genetic material of both donors.


Purebred refers to homozygous organisms for a particular set of traits due to extensive inbreeding or self-pollination.


A probability value, or p-value, measures the likelihood of observed results in selective breeding.


Qualitative Genetics

Qualitative genetics is the study of genes causing distinct, observable traits, like flower color or trichome presence, often following Mendelian inheritance patterns.

Quantitative Genetics

Quantitative genetics is the study of traits that are influenced by multiple genes and exhibit a range of variability, such as yield or height.

Quantitative Trait Locus (QTL)

A QTL is a specific region of the genome associated with the inheritance of a quantitative trait, often used in marker-assisted breeding.



Receivers are female plants that are pollinated, either by male or intersex female donors. See Donor

Reciprocal Cross

A reciprocal cross is a second cross between two cannabis varieties, but with the roles of the male and female parents reversed. This method helps determine if any traits are sex-specific.


Recombination is the process by which genetic material from both parents is combined and reshuffled during sexual reproduction, leading to genetic variation in offspring.


Respiration is the metabolic process where cells convert nutrients into energy and release oxygen.


Rodelization means allowing an unfertilized female to continue maturing past the typical harvest window, which forces it to express the dormant hermaphroditic trait and self-pollinate. 


Ruderalis is a subspecies that evolved close to the Arctic Circle and is characterized by its short stature, hardiness, and the autoflowering trait.



S1 denotes the first generation that results from selfing. See Selfing.


Sativa is, technically speaking, considered to be a variety of cannabis plants originating in Equatorial regions.


Scarification is the process of weakening, opening, or otherwise altering the coat of a seed to encourage germination.

Screen of Green (SCROG)

SCROGging is a form of low-stress training where plant branches are spread out using netting to maximize light distribution and increase yields.


Segregation is the separation or distribution of different gene variants (alleles) during the formation of gametes (pollen or ovules), leading to genetic variation in offspring.


Selection means choosing individual cannabis plants with desirable traits to be used as parents for the next generation, thereby gradually improving the overall quality of the population.

Selection Pressure

Selection pressures are the environmental or breeding factors that influence the survival and reproduction of certain cannabis plants with specific traits, thereby shaping the genetic composition of subsequent generations.

Selective Breeding

Selective breeding is intentionally choosing plants to cross to create offspring with preferred characteristics.


Selfing is the act of fertilizing a female cannabis plant with its own pollen, resulting in offspring that are highly similar to the parent.


Senescence is the aging process wherein the plant’s leaves turn yellow and die.

Single Seed Descent (SSD)

SSD is a method where a particular plant is self-pollinated, or selectively inbred, through successive generations using seeds from a single selected parent, aiming to create a stable cultivar with uniform traits.

Shoot Tip Culture

Shoot tip culture is a tissue culture technique that involves the excision and culturing of the shoot tips of a plant, often used for rapid propagation.


Skatole is an organic compound found in some plants and the fecal matter of birds and animals. It is responsible for the distinctive “skunk” scent of cannabis. 

Solvent-Based Extraction

Solvent-based extraction refers to the use of chemical solvents such as butane, hexane, and propane to produce cannabis extracts. The more appropriate term, however, is non-polar extraction. See Non-Polar Extraction

Solventless Extraction

Solventless extraction refers to cannabis extracts and concentrates produced without a chemical solvent. Instead, solventless extraction uses water, pressure, and/or agitation. The more appropriate term, however, is polar extraction. See Polar Extraction

Somaclonal Variation

Somaclonal variation is the genetic variability generated by some pathways in plant tissue culture. Common cannabis micropropagation methods are not subject to somaclonal variation.


Sterilization is the process of eliminating all living organisms and pathogens from a surface, equipment, or growth medium, often done using autoclaves, sterilizing agents, or heat.


The term “strain” is commonly misused in cannabis to describe a cultivar. It more appropriately refers to a genetic variant or subtype of fungus and bacteria. 

Strain Fatigue

Strain fatigue is the reduced efficacy and impact of specific cultivars on consumers with repeated use over time.


Stratification is the process of simulating natural winter conditions by exposing seeds to a period of cold and sometimes moist environment to promote germination.


Subculture refers to transferring a portion of a tissue culture, such as callus or shoot tips, onto a fresh growth medium to promote continued growth and development.


Substrate is the medium in which plants grow, providing them with support, nutrients, air, and water. Soil, coco fiber, cork, peat, and rockwool are all substrates.

Super Cropping

Super cropping is a high-stress training technique that involves gently bending or crushing the stems of plants to promote lateral growth and increase flower production. See High-Stress Training.

Synthetic Cannabis

Synthetic cannabis, sometimes known as “Spice” or “K2,” are chemically-engineered substances designed to mimic the effects of natural cannabis’s active components, but tend to have more unpredictable and potent effects due to variations in chemical composition and concentration.

Synthetic Seeds

Synthetic seeds are artificially created encasements containing plant tissue or somatic embryos developed through tissue culture that can germinate into a plant under suitable conditions.



Terpenes are a diverse group of aromatic compounds found in cannabis and other plants, responsible for their distinct smells and potential therapeutic effects.


The testa is the protective outer coat of a seed and is essential for guarding the embryo and influencing germination.


Thiols are sulfur-containing organic compounds known for their strong and often unpleasant odors, playing a significant role in the flavor and aroma profiles such as skunk, gas, and ammonia in various cannabis cultivars.


Topping is a pruning technique that involves removing the top growth of a cannabis plant to encourage bushier lateral growth and multiple main colas.


Totipotency is the ability of many plant cells to regenerate into a whole new plant when presented with proper stimuli.


Training is the use of techniques such as bending, tying, or pruning that manipulate the shape and structure of cannabis plants, maximizing light penetration and yield.


Traits are inheritable characteristics or properties, such as morphology, growth behavior, and biochemical profile.


A transgenic organism has been genetically modified or altered by introducing foreign DNA sequences from another species. One of the most well-known examples of transgenic plants are pest-resistant Bt-cotton and Bt-corn.


Transpiration is the process by which the roots absorb water, which moves up through the plant and is released into the atmosphere as water vapor through tiny pores called stomata.


Transplanting is moving a plant from one growing container or medium to another to accommodate the increasing size and promote healthy root development.


Trichomes are small, glandular structures found on the surface of cannabis flowers and leaves that produce and store cannabinoids and terpenes.

Tropical Volatile Sulfur Compounds

Tropical volatile sulfur compounds are found in cannabis and other plants and are associated with the aroma and taste of tropical fruits. 


True-to-seed plants replicate the characteristics of their parents from seeds.


Vapor Pressure Deficit (VPD)

Vapor pressure deficit is a metric that represents the difference between actual and saturated moisture levels in the air, influencing plant transpiration, nutrient uptake, and growth.


A variety is a subgroup within the species with distinct and stable features. It differs from a “cultivar,” which designates a plant variety that has been intentionally created or selected and maintained through cultivation for its desired traits. It can refer to a progeny of seeds from the same lineage, typically sharing similar genetic and phenotypic characteristics, and it generally refers to plants that naturally possess certain consistent features such as autoflower “varieties.”

Vegetative Stage

The vegetative stage is the initial growth phase and is characterized by the development of essential infrastructure, such as leaves and branches.



Washer is a slang term that refers to cannabis cultivars that are high-yielding when processed into water hash. See Bubble Hash.



Xylem is the vascular tissue responsible for the upward transportation of water and dissolved minerals from the roots to the rest of the plant, supporting processes such as photosynthesis and transpiration.