Let’s learn about autumn leaves

anthocyanins: A family of pigments that naturally give fruits and vegetables a red or blue hue. These chemicals are also potent antioxidants, which may make them useful defense compounds for their host plants (and people who dine on them).

bacteria: (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals). Bacteria are one of the three domains of life on Earth.

carotenoid: A pigment that tends to naturally provide fruits and vegetables a yellow or orange color. These chemicals also have antioxidant properties, which may make them useful defense compounds in plants.

chlorophyll: Any of several green pigments found in plants that perform photosynthesis — creating sugars (foods) from carbon dioxide and water.

conifer: Cone-bearing trees or shrubs such as the pine, fir, spruce or yew. Conifers are usually evergreen and have either needle-shaped or scale-like leaves.

conserve: To protect, as from loss or degradation.

deciduous: (in botany) Those trees and shrubs that lose their leaves in winter, each year, then grow new ones the next spring.

force: Some outside influence that can change the motion of an object, hold objects close to one another, or produce motion or stress in a stationary object.

forest: An area of land covered mostly with trees and other woody plants.

fungi: (sing: fungus) Organisms with one or more cells that reproduce via spores and feed on living or decaying organic matter. Examples include mold, yeasts and mushrooms.

gravity: The force that attracts anything with mass, or bulk, toward any other thing with mass. The more mass that something has, the greater its gravity.

herbivore: A creature that either exclusively or primarily eats plants.

hormone: (in botany) A chemical that serves as a signaling compound that tells cells of a plant when and how to develop, or when to grow old and die.

moisture: Small amounts of water present in the air, as vapor. It can also be present as a liquid, such as water droplets condensed on the inside of a window, or dampness present in clothing or soil.

photosynthesis: (verb: photosynthesize) The process by which green plants and some other organisms use sunlight to produce foods from carbon dioxide and water.

pigment: A material, like the natural colorings in skin, that alter the light reflected off of an object or transmitted through it. The overall color of a pigment typically depends on which wavelengths of visible light it absorbs and which ones it reflects. For example, a red pigment tends to reflect red wavelengths of light very well and typically absorbs other colors. Pigment also is the term for chemicals that manufacturers use to tint paint.

strain: (in biology) Organisms that belong to the same species and share some small but definable characteristics. For example, biologists breed certain strains of mice that may have a particular susceptibility to disease. Species of bacteria or viruses may develop strains when some members of the species gain mutations. Sometimes, specific strains are immune to drugs that would usually kill that species of microbe.

subnivium: The term for an ecosystem that develops in the space under a fairly long-lasting snowpack — one that’s at least 15 centimeters (six inches) deep. This snow creates an insulating blanket so that temperatures between it and the ground remain permanently just above freezing. Tunnels may develop creating the equivalent of tiny buried igloos. Many birds, mammals, insects, microbes, fungi and plants can survive harsh conditions by using this protected environment for various periods of time. While there, they often break down leaf litter to help enrich soils.

sun: The star at the center of Earth’s solar system. It is about 27,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.

tissue: Made of cells, it is any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.

weather: Conditions in the atmosphere at a localized place and a particular time. It is usually described in terms of particular features, such as air pressure, humidity, moisture, any precipitation (rain, snow or ice), temperature and wind speed. Weather constitutes the actual conditions that occur at any time and place. It’s different from climate, which is a description of the conditions that tend to occur in some general region during a particular month or season.