Weed is made of dried cannabis flower: plain plant tissue plus three families of compounds that do the real work. Cannabinoids such as THC and CBD set potency and the psychoactive effect. Terpenes supply smell and flavor. Flavonoids and other minor compounds fill out the chemistry. Everything else is plant basics, including cellulose, chlorophyll, water, sugars, and minerals. Those four groups are the criteria worth checking on any label, because they explain why two jars of flower with the same THC percentage can hit people in completely different ways.
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Plant material: cellulose, water, and trichomes
A cured bud is roughly 10 to 15 percent water by weight, with the rest being fibrous plant structure. Cellulose and lignin form the stems and leaf skeleton. Chlorophyll gives fresh flower its green color and its harsh, grassy taste before curing. Sugars, starches, and proteins make up a small share of the total mass.
The interesting part sits on the surface. Trichomes are tiny resin glands that look like frost under light, and they hold the cannabinoids and terpenes the plant produces. Growers judge harvest timing by trichome color, since clear heads mean early and amber heads mean the resin is breaking down.
Cannabinoids: the compounds that bind receptors
The plant makes more than 100 cannabinoids, but a handful drive most of what people feel. In a living plant, they exist mostly as acids, which is why raw flower does not get you high. Heat removes a carboxyl group and converts those acids into their active forms.
- THCA and THC. The main intoxicating pair. THCA becomes THC when you smoke, vape, or decarboxylate it in an oven.
- CBDA and CBD. Non-intoxicating. CBD shows up in tinctures, topicals, and low-THC flower.
- CBG. Often called the parent cannabinoid, since many others start as CBGA before enzymes redirect them.
- CBN. A breakdown product of THC that shows up more in older flower.
- CBC and THCV. Minor players that appear in small amounts and get studied for their own receptor activity.
Pros of paying attention to this group: it tells you whether a product will intoxicate you, and it lets you compare a 30 percent THC flower against a 12 percent one on equal footing. Cons: total THC on a label combines THCA and THC with a conversion factor, so the number is not the same as THC alone, and high percentages do not predict a better experience.
Terpenes: aroma, flavor, and possible interaction
Terpenes are aromatic oils the plant makes for the same reason other plants do: to attract pollinators and repel pests. They are also the reason two strains can smell like citrus and pine or like diesel and pepper. Common ones include myrcene (earthy, herbal), limonene (citrus peel), pinene (pine forest), linalool (lavender), beta-caryophyllene (black pepper), humulene (hops), and terpinolene (tea tree and citrus).
- Pro: terpenes guide your purchase. If a strain that helped you smelled like lemon and pine, a similar profile is a reasonable place to start.
- Con: labels list terpenes loosely, and storage, heat, and age all degrade them. A jar that sat on a shelf for a year smells nothing like it did at harvest.
Beta-caryophyllene is the one terpene known to bind directly to a cannabinoid receptor, which is why it gets extra attention in research.
Flavonoids and other minor compounds
Cannabis produces flavonoids, including cannflavin A and B, quercetin, kaempferol, and apigenin. Anthocyanins are the pigments behind purple buds, and they shift color with temperature during the grow. These compounds appear at low concentrations and are studied far less than cannabinoids, so treat strong claims about them with patience.
What is not in the plant
Smoke is not part of the plant. Burning flower creates tar, carbon monoxide, and ash that you inhale along with the cannabinoids. Vaporizing at controlled temperatures avoids combustion and produces far less of those byproducts. Edibles contain no plant material at all, just extracted cannabinoids in a fat or oil base. Distillate vapes strip everything except cannabinoids, then add terpenes back, which is why they taste consistent and flat compared with whole flower.
How to use this when you buy
Match the chemistry to the job. For evening wind-down, look for THC-dominant flower with myrcene and beta-caryophyllene, and start low because the effect builds over 10 to 20 minutes when inhaled. For daytime focus, a lower-THC cultivar with pinene and limonene tends to sit lighter. For anyone who wants no intoxication, CBD-dominant flower or a CBD tincture covers that need without the high.
Check the batch testing panel before you commit. A useful certificate of analysis reports total THC and CBD, the terpene list, and results for pesticides, mold, heavy metals, and residual solvents. That document says more about what is in the jar than any strain name or marketing claim.