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Glossary

Plant care, climate, environment, and ecology—in plain language.

82 terms · A–Z

A

Acclimation

Plant care

A plant’s adjustment to changed conditions, such as brighter light or cooler air. Gradual changes reduce stress.

Aeration

Soil and water

The supply and exchange of air around roots. Waterlogged growing media leave little room for the oxygen roots need.

Annual

Plant basics

A plant whose life ends after one growing season of growth and reproduction. Some tender perennials are also grown as annual garden plants.

Areole

Plant basics

A specialized growing point on a cactus where spines, hairs, flowers, or branches may arise. Areoles help distinguish cacti from similar-looking succulents.

B

Biennial

Plant basics

A plant that typically grows leaves and roots in its first season, then flowers, produces seed, and dies in its second.

Biodiversity

Ecology

The variety of life, including differences within species, among species, and among ecosystems. A garden contributes through both its organisms and their relationships.

Biome

Environment

A broad ecological region characterized by its climate and major vegetation types. Deserts, grasslands, and tropical rainforests are examples.

Botanical name

Plant basics

A scientific plant name used to reduce the ambiguity of common names. A species name combines a genus and a specific epithet, as in Sempervivum tectorum.

Bract

Plant basics

A leaf associated with a flower or flower cluster that may differ from ordinary foliage. Colorful bromeliad bracts can be mistaken for petals.

C

Cactus

Plant basics

A member of the cactus family, Cactaceae. Cacti have areoles; the family includes forest epiphytes as well as desert plants.

See also: Areole · Epiphyte · Succulent

Chilling injury

Climate

Damage caused by temperatures above freezing that are too cold for a sensitive plant. A frost-free night can still injure a tropical plant.

Chlorosis

Plant care

Loss of normal green color as chlorophyll becomes scarce. Yellow leaves can reflect nutrient problems, root damage, unsuitable conditions, or normal aging.

Climate

The long-term patterns of weather in a place, including seasonal cycles, variability, and extremes. Climate helps explain a plant’s native growing conditions.

Cultivar

Plant basics

A named selection maintained in cultivation for particular traits. Cultivars may originate through breeding or from plants selected in nature or gardens.

Cutting

Propagation

A piece of stem, leaf, or root used to produce a new plant. Which parts can regenerate depends on the species.

D

Deciduous

Plant basics

Describes a plant that sheds its foliage during a recurring season, often winter or a dry period, and later grows new leaves.

Division

Propagation

Making new plants by separating an established plant into viable portions with growing points and enough roots or storage tissue to recover.

Dormancy

Plant basics

A resting state in which growth is suspended or strongly restricted. Its timing and release depend on the plant and its environmental cues.

Drainage

Soil and water

The movement of excess water away from roots through the growing medium and, in containers, out of the pot.

Drought tolerance

Plant care

The ability to endure limited water after establishment. It varies with species, roots, weather, and growing conditions; it does not mean a plant never needs water.

E

Ecology

The study of how organisms interact with one another and with their physical surroundings. Pollination, competition, and decomposition are ecological processes.

Ecosystem

Ecology

Organisms and their physical surroundings considered together as an interacting system. A pond, woodland, or water-filled bromeliad can be studied this way.

Environment

The living and nonliving surroundings that affect an organism, including light, water, soil, temperature, and neighboring organisms.

Epiphyte

Environment

A plant that uses another plant as a place to grow without feeding parasitically on it. Many orchids, bromeliads, and forest cacti grow this way.

Etiolation

Plant care

Growth that becomes elongated and often pale under inadequate light. Long, weak gaps between leaves can indicate that a plant needs more light.

Evapotranspiration

Soil and water

Water lost to the atmosphere through evaporation from surfaces plus transpiration from plants. Both contribute to how quickly a planting dries.

Evergreen

Plant basics

Describes a plant that normally carries living leaves throughout the year. Individual leaves still age and are replaced.

F

Fertilizer

Plant care

Material supplied to provide plant nutrients. It cannot replace adequate light, suitable temperatures, water, or healthy roots.

Fibrous roots

Plant basics

A root system with many branching roots of similar size instead of one strongly dominant main root.

Frost

Climate

Ice crystals forming on a surface cooled below freezing. Plant surfaces can become colder than the reported air temperature on clear, calm nights.

See also: Chilling injury · Microclimate

Full sun

Plant care

A garden-light category generally meaning at least six hours of direct sunlight a day. Season, latitude, heat, and species affect what is suitable.

See also: Partial shade · Indirect light

G

Genus

Plant basics

A taxonomic group of related species and the first word in a species’ scientific name. Sempervivum is the genus of many Hens & Chicks.

Germination

Propagation

The beginning of a seed’s growth into a seedling. Water, oxygen, suitable temperature, and sometimes particular light or pretreatment conditions are needed.

H

Habitat

Environment

The place and conditions in which an organism lives. A rocky crevice and a forest branch offer very different habitats even in the same region.

Hardiness zone

Climate

A USDA zone summarizes a location’s average annual coldest winter temperature. It does not describe all the conditions a plant needs to thrive.

Host plant

Ecology

A plant used by another organism for food, shelter, or development. In butterfly gardening, it usually means a plant eaten by the caterpillars.

Hybrid

Plant basics

An offspring produced by crossing genetically distinct parents, often from different species or cultivated lines. A hybrid is not automatically sterile.

I

Indirect light

Plant care

Light reaching a plant without direct sunbeams on its leaves, often after scattering or reflection. Bright indirect light is different from a dim room.

Internode

Plant basics

The portion of a stem between neighboring nodes. Its length helps reveal a plant’s normal growth form or stretching under poor light.

Invasive

Ecology

In the U.S. policy sense, a non-native organism whose introduction causes, or could cause, harm. A vigorous garden plant is not automatically invasive.

See also: Non-native · Naturalized · Native

L

Light-dependent germination

Propagation

Germination that requires a suitable light signal. Such seeds are often sown at the surface or covered very lightly, following species-specific instructions.

Lithophyte

Environment

A plant that grows on rock or in rock crevices. Accumulated debris and pockets of moisture may support its roots.

M

Microclimate

Climate

Conditions in a small area that differ from the wider surroundings. A sheltered wall, shaded courtyard, or low frost pocket can change plant performance.

Monocarpic

Plant basics

Describes a plant or rosette that flowers once and then dies. In Hens & Chicks, surviving offsets can keep the colony growing.

Mutualism

Ecology

An interaction in which both partners benefit. The balance of benefits can change with conditions rather than remaining fixed.

Mycorrhiza

Ecology

An association between a fungus and a plant’s roots. The fungus can help obtain nutrients while receiving carbon compounds from the plant.

N

Native

Ecology

Naturally occurring in a particular region or ecosystem without human introduction. Always name the region: native to the United States does not mean native to Indiana.

Naturalized

Ecology

Describes an introduced population that reproduces and persists without continued planting. Naturalization alone does not establish that it is invasive.

See also: Native · Non-native · Invasive

Nectar

Ecology

A sugary liquid produced by certain plant glands. Floral nectar can reward pollinating visitors; some plants also have nectar glands outside their flowers.

Niche

Ecology

The conditions and resources a species uses, together with its ecological interactions. Several species can share a habitat while occupying different niches.

Node

Plant basics

A point on a stem where leaves, buds, or branches arise. Many stem cuttings form roots near a node.

Non-native

Ecology

Present outside its natural range through human activity, whether intentional or accidental. A non-native plant may remain cultivated, become naturalized, or become invasive.

See also: Native · Naturalized · Invasive

N–P–K

Plant care

The three main fertilizer-label numbers: nitrogen, phosphate, and potash percentages by weight. Phosphate and potash are reporting forms for phosphorus and potassium.

O

Offset

Propagation

A small daughter plant developing from the parent’s base or a short connecting stem. The “chicks” of Hens & Chicks are offsets.

Overwintering

Plant care

Keeping a plant alive through winter in conditions suited to its needs. Depending on the species, this may involve outdoor dormancy, shelter, or indoor growth.

P

Partial shade

Plant care

A broad garden-light category between full sun and full shade, commonly about three to six hours of direct sun. Morning and afternoon exposure differ in intensity.

Perennial

Plant basics

A plant that can live for more than two years. It may be herbaceous or woody, and it may still be unable to survive local winters.

pH

Soil and water

A measure of acidity or alkalinity. Values below 7 are acidic and above 7 alkaline; soil pH influences nutrient availability.

Photoperiod

Climate

The daily duration of light. Day length and the accompanying dark period can influence flowering, dormancy, and other seasonal responses.

Photosynthesis

Plant basics

The process by which plants use light energy to make sugars from carbon dioxide and water, releasing oxygen. Those sugars support growth and other life processes.

Pollination

Ecology

Transfer of pollen to a receptive reproductive structure. In flowering plants, pollen reaches the stigma; successful fertilization is a later step.

Pollinator

Ecology

An animal that moves pollen between receptive flowers. Bees are familiar examples, but flies, beetles, moths, birds, and other animals also pollinate plants.

Propagation

Producing additional plants, either from seeds or from plant parts such as cuttings, divisions, and offsets.

See also: Cutting · Division · Germination

R

Respiration

Plant basics

Cellular reactions that release usable energy from sugars. Plant roots, stems, and leaves respire both day and night.

Rhizome

Plant basics

A stem that usually grows horizontally below or along the ground and can produce new roots and shoots. It is not a root.

Root hair

Plant basics

A fine extension of an outer root cell that increases the root’s absorbing surface. Root hairs are different from the larger branching roots.

Root rot

Plant care

Breakdown of root tissue, often involving pathogens favored by persistently wet, poorly aerated conditions. Similar symptoms can have different causes.

Rosette

Plant basics

Leaves arranged closely around a central growing point, often near ground level. Hens & Chicks forms compact rosettes.

S

Scarification

Propagation

A treatment that makes a resistant seed coat more permeable. Methods depend on the species and differ from the temperature treatments used in stratification.

Self-seeding

Propagation

A plant producing seed that germinates nearby without deliberate sowing. This is different from spreading by runners, rhizomes, or offsets.

Species

Plant basics

A basic unit used to classify organisms. Species boundaries reflect evidence about ancestry and biological differences and can be difficult to define in some plant groups.

See also: Genus · Botanical name · Hybrid

Stolon

Plant basics

A horizontal stem that extends across or near the surface and may form new plants at its nodes. Often called a runner.

Stomata

Plant basics

Adjustable pores in a plant’s surface, especially its leaves. They allow gas exchange and help regulate water loss.

See also: Transpiration · Photosynthesis

Stratification

Propagation

Holding seeds under specified moist and temperature conditions to help release dormancy. Some need cold, some warmth, and some a sequence of treatments.

See also: Scarification · Dormancy · Germination

Substrate

Soil and water

The material or surface in which a plant grows, such as soil, potting mix, bark, or rock. Match its air and water behavior to the plant.

See also: Drainage · Epiphyte · Lithophyte

Succulent

Plant basics

A plant with substantial water storage in fleshy leaves, stems, or roots. Succulence occurs in many unrelated plant families and does not always indicate a desert origin.

T

Taproot

Plant basics

A root system dominated by a main downward-growing root with smaller lateral branches. Its depth depends on species and soil conditions.

Tender

Climate

Describes a plant easily damaged by cold in the location being discussed. The harmful temperature varies by species, condition, and exposure time.

Terrestrial

Environment

Living or growing on land. In discussions of orchids, bromeliads, and cacti, it often distinguishes soil-growing species from epiphytes.

Transpiration

Soil and water

Water vapor leaving a plant, mainly through leaf pores. Water moving from roots toward leaves replaces this loss.

W

Weather

Climate

Atmospheric conditions over hours or days, such as tonight’s temperature or tomorrow’s rain. Weather is the immediate situation within a longer climate pattern.

X

Xerophyte

Environment

A plant adapted to dry conditions. Water storage is one strategy; small leaves, protective surfaces, or seasonal dormancy are other possibilities.

See also: Succulent · Drought tolerance

References and further reading

Definitions are written for this project. These botanical, Extension, and government resources provide further detail. Read care guidance for the particular species as well as the general term.

All project references · Updated 2026-09-25