A drug made from the Cannabis sativa plant, often used recreationally to create a mental or physical high. Marijuana can make it hard to focus, learn, or remember things. It also affects your balance and coordination. It makes your eyes red and your heart rate faster. It can lead to respiratory problems, and some medical procedures, like a heart bypass surgery, can be more difficult if you smoke marijuana. Marijuana can increase your risk of heart attack, stroke, or liver disease. It can also cause addiction, depression, anxiety, and other health problems. Marijuana may make it harder to drive, and you should avoid it if you’re pregnant or breastfeeding. It can also make you more likely to use other drugs, including opioids, which could be dangerous. Heavy marijuana users may have more trouble after a procedure, and long-term marijuana use can raise your risk of depression.
A plant that grows wild in an area where it is unwanted: The garden was overrun with weeds. To identify a weed, compare it with photographs and written descriptions in a field guide or manual. This method can be fast and accurate if you have narrowed the list of possibilities to a few species with similar features, such as leaf shape or flower color. A strong likeness of the specimen to a photo or diagram and a close match with the manual’s written description suggest a correct ID.
Weeds are often considered nuisance plants, but they perform valuable ecosystem services. They quickly establish on and protect exposed or degraded soil, prevent erosion, and provide organic matter; they are often nutritious food for livestock and humans; and they host beneficial insects that control pests of crops and vegetables. Some weeds even produce useful materials, such as fuel for biofuels or fabrics.