Serration is the toothed margin of a leaf. Cannabis leaflets are serrate: a regular row of sharp teeth along each edge, angled toward the tip. The degree of serration (fine, coarse, double) varies by genotype and is one of the visible leaf traits used in plant descriptions and variety test guidelines.
In practice
Serration is a quick identifier. The first true leaves of a seedling are serrated; the cotyledons are not. That is how growers tell them apart at a glance. Adult leaflets keep their teeth unless something distorts the leaf.
Changes along the margin are diagnostic. Burnt tips that creep inward point to excess salts or high EC; rust-coloured spotting along the edges often points to potassium or calcium issues, after pH and root zone are ruled out; tightly curled, twisted margins with odd serration on new growth can indicate broad mites or herbicide drift.
Some leaf-shape mutants, such as smooth-edged "duckfoot" types, lose normal leaflet separation and serration. These are genetic variants, not deficiencies.
Don't confuse with
- Leaflet: the blade that carries the serrated edge.
- Clawing: leaflet tips curling down, a separate symptom.
- Trichomes: hair-like outgrowths on the surface, not the edge.
The first leaves produced by the shoot tip after the cotyledons, with the plant's characteristic serrated leaflets.Nutrient burn is browning and crisping of leaf tips, then margins, caused by a root-zone salt concentration (EC) higher than the plant can handle.EC (electrical conductivity) measures how well a solution conducts electricity, a proxy for total dissolved salts; growers read it in mS/cm to gauge nutrient strength.pH measures how acidic or alkaline a solution is on a 0–14 scale; in growing it controls nutrient uptake, with soil best near 6.0–7.0 and hydro 5.5–6.5.The root zone is the volume of medium or solution where a plant's roots live, including its water, air, temperature, pH, EC and microbes.Polyphagotarsonemus latus, a microscopic tarsonemid mite whose toxic feeding twists, glazes and stunts new growth; often mistaken for calcium deficiency or heat stress.A nutrient deficiency is a shortage of an essential element in the plant tissue, causing characteristic symptoms; the cause is often pH or uptake rather than an empty feed.A hair-like outgrowth of the plant's skin; in cannabis the glandular types make and store the resin holding cannabinoids and terpenes.One of the separate serrated blades that make up a palmate cannabis leaf; a mature fan leaf typically has five to eleven leaflets.A large palmate cannabis leaf with several long leaflets on a long petiole; fan leaves do most of the plant's photosynthesis and carry few trichomes.
