Cannabis: botany, uses, history and legal status

Botanical characteristics and chemistry

Cannabis is typically an annual herbaceous plant with palmate leaves and separate male and female flowers in most cultivated strains. Female inflorescences develop dense clusters of glandular trichomes that produce a resin rich in cannabinoids and aromatic terpenes. The best-known cannabinoid is THC (tetrahydrocannabinol), which is largely responsible for the plant's psychoactive effects. Other important cannabinoids include cannabidiol (CBD) and dozens of related compounds; their relative proportions differ between varieties and influence effects and potential therapeutic uses.

Traditional, industrial and culinary uses

Cannabis has been used in many societies for millennia. Different selections of the plant are cultivated for specific purposes:

• Fiber and textiles: low-THC cultivars used for hemp fiber produce strong bast fibers for rope, canvas and composite materials.
• Seeds and food oils: hemp seeds yield nutritious oil and protein-rich food products; see seeds and seed oil for culinary uses.
• Psychoactive and ritual use: flowers rich in THC are consumed by inhalation or ingestion and can produce euphoric or sedative effects.
• Pharmaceuticals and therapeutics: certain standardized preparations and cannabinoid medicines are used under medical supervision for specific conditions.

Origins, ecology and cultivation

Cannabis likely originated in temperate regions of Central and East Asia and spread with human migrations and trade. In nature and cultivation, the production of resinous cannabinoids is thought to have ecological roles such as defense against herbivores, insects and ultraviolet light; this protective function has been suggested by ecological studies of plant secondary metabolites (natural environment and protection). Selective breeding over centuries produced lines optimized for fiber, seed, or resin content, and modern breeding has created many hybrid varieties adapted to diverse climates.

History and legal status

During the 19th and 20th centuries, many countries introduced strict controls on cannabis and its extracts, and in many places it became categorized as an illegal drug (criminalization). Since the late 20th and early 21st centuries, regulatory approaches have diverged: some jurisdictions have decriminalized or legalized adult recreational use, others permit medical use under regulated frameworks, and enforcement priorities vary widely. A number of governments now authorize cannabinoid-based medicines or allow clinical use for specified conditions (medical use).

Distinctions and notable facts

Important distinctions to understand include the difference between hemp (low-THC cultivars grown for fiber and seed) and drug-type cannabis (high-THC cultivars grown for psychoactive uses). The taxonomy of cannabis remains debated among botanists, and the legal, social and scientific landscapes continue to evolve rapidly. In research and public policy, the plant is discussed across multiple domains: agriculture, medicine, law, public health and industry.

Further information

Readers seeking more detail can consult botanical references and authoritative public health or regulatory sources for up-to-date information on cultivation, safety, therapeutic indications and local laws. For introductions to specific topics mentioned here, follow links to resources on species and classification (species overview), cannabinoid chemistry (THC and cannabinoids), recreational effects (euphoria and effects), hemp industry uses (hemp products), nutritional uses of seeds (seed oil and food), ecology and origins (natural habitat), plant defense hypotheses (ecological role), historical regulation (legal history) and medical frameworks for cannabinoids (medical cannabis).