The complexity of classifying a tree

Plants use physical and chemical defenses to protect themselves

Tree bark is difficult to chew and resistant to pathogens, while the waxy cuticle on the surface of leaves deters insects and microbes. Some plants possess thorns, spines, and prickles to discourage predators. Plant cells can also produce antimicrobial toxins or release compounds to alert parasitic wasps to lay eggs in attacking insects.

How trees transport water from roots to leaves

Trees move water to their extremities via a deft system starting from the roots to the leaves. See how it works in this short video breaking down the process in a Douglas fir.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

Tree rings can reveal centuries of environmental change and natural events

The width and shape of tree rings reflect yearly growth conditions like rainfall or snowfall. Scars in the rings can record disruptions such as fires, avalanches, or earthquakes, explaining when and how those events occurred.

Learn about the basic anatomy of mosquitoes

This short explainer video breaks down the mosquito's general body components, highlighting how mosquitoes breathe, fly, and more. It also touches on how experts can tell different mosquito species apart.

Fungi can cause disease, but they’re also our planet’s key decomposers

Fungi are their own taxonomic kingdom separate from flora and fauna, acting as the key decomposers and nutrient recyclers for our planet. Watch this video to understand the diverse types of fungi and the stages of the fungal life cycle. This video illustrates how fungi species may spread, eat nematode worms, damage nearby plants, and much more.

Minerals, crystals, rocks, and gems explained

Have you ever wondered what differentiates a mineral from a rock or a crystal from a gem? This three-minute video from the American Museum of Natural History elaborates on the unique properties and compositions that separate minerals, rocks,...

Behind the fascinating disguising mechanism of camouflage

Camouflage—nature's master game of hide-and-seek—is more complex than simply how things look. The disguising process required millions of years of evolution that have programmed how our brains take shortcuts. Watch this video to see examples of camouflage and understand how we process it.

The three categories of photosynthesis, which each help plants survive in different environments

In the vast majority of plants, C3 photosynthesis produces three-carbon intermediate molecules in the Calvin cycle within the cells of leaves. Plants in hot, dry climates use C4 photosynthesis across two types of cells to produce four-carbon molecules before the Calvin cycle. Plants in drought conditions use CAM to store carbon dioxide as an acid at night, minimizing water loss.

The Köppen-Geiger system divides Earth’s climate into five main categories

This classification system, developed by a German-Russian botanist and a German climatologist, results from differences in the intensity of solar radiation and rainfall in different parts of the world. Each category is further divided into multiple coded zones.

Why we have different seasons

Visualize just how exactly seasons come to be with this animation of the earth in relation to the sun, and see how earth's tilt determines our seasons.

Wine is divided between Old World and New World

The distinction stems from both geography and winemaking technique and tradition. This video breaks down how different viticultural regions fit into each category and the common traits of both Old World and New World wines. It also provides helpful tips for reading Old World wine labels.

Unlike fruits, the category of 'vegetables' is a culinary term, not a scientific one

Within botany, fruits are defined as the ripened ovaries of flowering plants, and include apples, grapes, tomatoes, avocados, green beans, peppers, and almonds. In the kitchen, "vegetables" is an umbrella term that encompasses many fruits and other parts of plants, such as leaves (lettuce, kale) and roots (carrots, beets).

Dinosaurs are defined by specific traits that many dinosaur-like creatures lack

Although pterodactyls, mosasaurs, crocodilians, and other organisms are mistaken for dinosaurs, they do not have upright legs or specific hip structures characteristic of the terrestrial reptiles. Some, like the Dimetrodon, are more closely related to humans than dinosaurs.

Companies often use different share classes, like Class A or Class B, to structure ownership

Share classes refer to specific types of company stock that are distinguished by the rights they grant, such as voting power and dividend access.

Understanding the distinctions between coffee types

If you’ve ever felt overwhelmed looking at a coffee shop menu, you're not alone. Here's a breakdown between common coffee styles. Click through the link to see similar guides to espresso and cold drinks.

What do psychedelic plants look like?

Far from the drippy aesthetic often associated with psychedelics, the plants powering naturally occurring psychoactive experiences may not stand out as anything special. This database offers a visual guide to psychoactive plants and fungi. Clicking on the title of a particular plant, such as yerba mate, will bring up a secondary screen with various hyperlinked images, such as the plant itself, related botanical drawings, and molecular structures.

A simple visual explanation of how blockchains work

Blockchains are decentralized, distributed, and digital methods to record transactions and prevent alterations and tampering of the record. That's a simplified definition. This easy-to-understand six-minute video further and better explains what blockchains are and how they work using colorful illustrations and clear, concise clarifications on their processes and what makes them so special.

How the number of subatomic particles helps identify different types of atoms

Different elements, such as oxygen and nitrogen, can be distinguished by the number of protons in each, since all atoms of the same element have the same number of protons. Isotopes of a given element have the same number of protons but different numbers of neutrons, while ions are atoms possessing different numbers of electrons than protons.

There are over 20,000 trees on the National Mall

Nearly 4,000 of the Mall's trees are cherry trees, all maintained by a small National Park Service arborist team that provides year-round, science-based care to address soil compaction, root damage, and heavy visitor traffic.

The features that make our voices unique

Human voices are about as unique as fingerprints: similar instruments but with endless variations. We each produce sound in the same physiological way, but when we talk we’re dropping clues about who we are, what we do, and where we’re from.

Stem cells have the ability to self-renew

Stem cells have remarkable potential for new medical therapies. But to understand what makes stem cells so special, you must understand exactly what they are, and what they’re capable of doing. This page offers an accessible introduction to stem cell biology and their unique properties.

A mathematical and visual analysis distinguishing chaos from randomness

Random systems lack any underlying pattern or causal relationships, while chaos is mathematically deterministic because the behavior follows established laws of nature. In 3D plots, chaotic systems produce outputs that approximate a mathematical function, while random points appear as statistical noise.

Colored paint lines on new tires mark different types in the factory

Each stripe helps warehouse workers and distributors identify tire types at a quick glance. This innovation became important a century ago as manufacturers scaled operations and developed distinct product lines.

Are burritos sandwiches?

In this video, we trace the burrito's origins, explore the legal and culinary battles around its classification, and break down why this seemingly simple food raises such a complicated question.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Many legends about George Washington, including his supposed wooden teeth and the story of cutting down the cherry tree, lack evidence.

Poison ivy's characteristic rash is caused by an allergic response to an oily compound in the plant called urushiol.

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

Learn how to read a prospectus, the juicy document that any company must file with the SEC before going public.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Georgia O'Keeffe's flower paintings are often assumed to be sexual, though the artist claimed she was simply interested in highlighting the beauty of flowers that most people neglect

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.