Glossary of Terms
A
achene
A small, dry one-seeded indehiscent fruit that does not open at maturity to release the seed. Learn more.
actinomorphic
For a flower having radial symmetry, divisible into identical halves along two or more planes. Learn more.
adelgids
a family of aphid-like insects that feed exclusively on conifers and typically are covered with white waxy material. Learn more.
aeration
Loosening soil or compost to improve oxygen availability for roots and microbes. Learn more.
aeroponics
A method of growing plants in air or mist environments without the use of soil. Learn more.
aggregate stability
The ability of soil aggregates to resist disintegration from water or mechanical disturbance, influencing erosion and infiltration. Learn more.
agroecology
The study and application of ecological principles to agricultural systems to promote sustainability and biodiversity. Learn more.
agroecosystem
An ecosystem managed by humans for agricultural production while maintaining ecological processes and biodiversity. Learn more.
agroforestry
A land management system combining trees or shrubs with crops or livestock to enhance productivity and biodiversity. Learn more.
air layering
A propagation method where roots are induced to form on a stem while still attached to the parent plant. Learn more.
alkaline
having a basic reaction containing hydroxide ions (OH−) and turning red litmus blue when in solution. Learn more.
allele
One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome. Learn more.
allelic variation
Differences in the DNA sequence of alleles at the same gene locus, contributing to genetic diversity. Learn more.
allelopathy
Chemical inhibition of one plant by another through compounds released into the environment. Learn more.
alternaria leaf spot
A fungal disease caused by Alternaria species, leading to circular dark lesions with concentric rings on leaves. Learn more.
alternate
an arrangement of leaves or other parts not opposite or whorled; parts situated one at a node, as leaves on a stem. Learn more.
alternate host
one of two kinds of plants on which a parasitic insect or fungus (such as rust) must develop to complete its life cycle. Learn more.
angiosperms
Also known as “flowering plants,” they are the largest and most diverse group of plants on Earth and are distinguished by their flowers and the production of seeds protected by a fruit Learn more.
anion exchange capacity (aec)
The total amount of negatively charged ions a soil can adsorb, important for nutrient retention and availability. Learn more.
annual
A plant that completes its life cycle—from germination to seed production—within one growing season. Learn more.
annual bed
A garden bed replanted each year with new annuals for continuous seasonal color. Learn more.
anthracnose
A group of fungal diseases causing dark, sunken lesions on leaves, stems, or fruit. Learn more.
APG
Acronym for the Angiosperm Phylogeny Group, an organization that establishes modern plant classification systems. Learn more.
aphid
Small, soft-bodied insects that suck sap from plants, often causing curling leaves and transmitting viruses. Learn more.
apical meristem
A region of actively dividing cells at the tips of roots and shoots responsible for primary growth. Learn more.
apple scab
A fungal disease of apples and pears that causes dark, scabby lesions on leaves and fruit. Learn more.
aquaponics
A system combining aquaculture with hydroponics where fish waste provides nutrients for plants. Learn more.
arbor
A garden structure that supports climbing plants and often provides shade or a passageway. Learn more.
arid gardening
Gardening practices adapted to dry climates emphasizing water conservation. Learn more.
armyworm
Caterpillars that feed in large groups on grasses and crops, capable of rapid defoliation. Learn more.
armyworms
caterpillar species closely related to cutworms that often move in masses through crop stands while stripping foliage. Learn more.
aster yellows
A phytoplasma disease causing chlorosis and deformed flowers in many ornamentals and vegetables. Learn more.
authority
The person credited with publishing the first valid description and name for a plant. Learn more.
axillary bud
A bud that forms in the axil of a leaf and may develop into a branch or flower. Learn more.
B
bacteria
unicellular microscopic organisms that lack chlorophyll and multiply by fission. Learn more.
bacterial blight
A general term for diseases caused by pathogenic bacteria that lead to leaf spots, wilting, or dieback. Learn more.
bacterial soft rot
A bacterial disease that causes watery decay in vegetables and tubers, common in wet or humid conditions. Learn more.
bacterial spot (fruit trees/vegetables)
Bacterial infections that cause leaf spots and fruit blemishes on stone fruit and peppers. Learn more.
bacterial wilt
A bacterial infection that clogs plant vascular tissue, causing sudden wilting. Learn more.
bacterium
a single-celled microscopic organism that lacks chlorophyll and multiplies by fission. Learn more.
bagworm
Moth larvae that construct protective cases from silk and plant material and feed on foliage. Learn more.
bare root
A plant sold with its roots free of soil, typically dormant and suitable for transplanting. Learn more.
basal
pertaining to the base or point of attachment of an organ, such as leaves at the base of a plant. Learn more.
basal rosette
A circular arrangement of leaves at the base of a plant, common in biennials like carrots and dandelions. Learn more.
base saturation
The proportion of a soil’s cation exchange sites occupied by basic cations (Ca²⁺, Mg²⁺, K⁺, Na⁺), used to assess fertility. Learn more.
basionym
The first validly published name given to a genus or species, forming the base for later names. Learn more.
bean mosaic virus
A viral disease producing mottled, distorted leaves and reduced yields in legumes. Learn more.
beneficial insect
An insect that preys on pests or pollinates crops, aiding in pest control and reproduction. Learn more.
biennial
A plant that completes its life cycle over two growing seasons, flowering and setting seed in the second. Learn more.
biochar
Charred organic matter added to soil to improve fertility, structure, and carbon sequestration. Learn more.
biodegradable
Capable of being decomposed by bacteria or other natural organisms, reducing environmental impact. Learn more.
biodiversity
The variety of living organisms in an ecosystem, essential for ecological stability and resilience. Learn more.
biodynamic farming
A holistic agricultural system combining organic methods with lunar and cosmic cycles to enhance soil and crop vitality. Learn more.
biogeochemical cycle
The movement of elements such as carbon, nitrogen, and phosphorus through biological, geological, and chemical processes. Learn more.
biological control
The use of living organisms such as predators or pathogens to control pest populations. Learn more.
bipinnate
A compound leaf in which each leaflet is further divided into smaller leaflets. Learn more.
black spot (rose)
A common fungal disease on roses producing circular black lesions on leaves. Learn more.
blight
Rapid browning and death of plant tissue caused by fungi, bacteria, or environmental stress. Learn more.
blossom end rot
A physiological disorder caused by calcium imbalance, resulting in dark, sunken lesions on the blossom end of fruits. Learn more.
bokashi
An anaerobic fermentation process to pre-digest kitchen scraps before soil incorporation. Learn more.
bolt (bolting)
Premature flowering and seed production, often triggered by heat or day length. Learn more.
bonsai
The Japanese art of growing miniature trees in containers through pruning and training. Learn more.
Botanical garden
A garden dedicated to the collection, cultivation, and display of a wide range of plants labeled with their botanical names. Learn more.
Botanical illustration
The art and science of depicting plants with accurate botanical detail for identification and study. Learn more.
botany
The scientific study of plants, their structure, growth, reproduction, and ecology. Learn more.
botrytis blight (gray mold)
A fungal disease that infects flowers, leaves, and fruit under cool, damp conditions. Learn more.
boxwood blight
A serious disease of boxwood caused by Calonectria species, leading to leaf spots, defoliation, and stem lesions. Learn more.
bract
A modified or specialized leaf often associated with a reproductive structure such as a flower or inflorescence. Learn more.
bracts
a reduced leaf often scale-like and usually associated with a flower or inflorescence. Learn more.
broadfork
A hand tool with long tines used to aerate and loosen soil with minimal disturbance. Learn more.
brown patch
A turfgrass disease caused by Rhizoctonia solani leading to circular patches of brown turf. Learn more.
buffer strip
A vegetated area next to a water body that helps filter runoff and protect water quality. Learn more.
burlap
A coarse woven fabric used for root balls, winter protection, and erosion control. Learn more.
C
cabbage looper
A green caterpillar pest of cruciferous crops, named for its looping movement. Learn more.
caliche
A hardened soil layer cemented by calcium carbonate that impedes drainage and root growth. Learn more.
callus (plant)
Wound tissue that forms over cuts and can develop roots or shoots in propagation. Learn more.
calyx
the outer whorl of flower parts, usually green, that encloses the petals and other floral parts when in bud. Learn more.
cambial zone
The layer of meristematic tissue between the xylem and phloem where secondary growth occurs. Learn more.
cambium
The layer of actively dividing cells between the xylem and phloem that enables secondary growth in plants. Learn more.
canes
long, woody, and flexible stems rising from the ground, typical of brambles and roses. Learn more.
canker
Localized areas of dead tissue on stems or branches, often caused by fungal or bacterial infection. Learn more.
carbon cycle
The biogeochemical cycle through which carbon moves among the atmosphere, oceans, soil, and living organisms. Learn more.
carbon footprint
The total greenhouse gas emissions caused directly or indirectly by an individual, organization, or activity. Learn more.
carbon sequestration
The long-term storage of carbon dioxide in vegetation, soils, or the ocean to mitigate climate change. Learn more.
carpel
The basic female reproductive unit of a flower, consisting of ovary, style, and stigma. Learn more.
carrot rust fly
A root-feeding fly whose larvae tunnel into carrots, parsnips, and related crops. Learn more.
carrying capacity
The maximum population size of a species that an environment can sustain indefinitely. Learn more.
cast skins
the outer layer of an exoskeleton shed by an insect or mite and often seen on leaves or twigs. Learn more.
caterpillar
The larval stage of moths and butterflies, many species being major plant defoliators. Learn more.
cation
A positively charged ion, such as potassium (K⁺) or calcium (Ca²⁺), essential for plant nutrition and soil chemistry. Learn more.
cation exchange capacity
A measure of soil’s ability to hold and exchange positively charged nutrient ions. Learn more.
cedar-apple rust
A rust disease requiring juniper and apple hosts, producing galls on juniper and spots on apple leaves. Learn more.
chilling hours
Accumulated hours of cold required by some plants to break dormancy and flower properly. Learn more.
chlorosis
Yellowing of leaves due to insufficient chlorophyll, often from nutrient deficiency or poor conditions. Learn more.
clay mineralogy
The study of clay minerals and their structure, affecting soil texture, nutrient exchange, and water retention. Learn more.
clay soil
Soil with a high proportion of fine particles that holds water and nutrients but drains slowly. Learn more.
cleistogamy
A form of self-pollination where flowers do not open, ensuring seed set in adverse conditions. Learn more.
climate control (greenhouse)
The regulation of temperature, humidity, and light in greenhouse environments to optimize plant growth. Learn more.
cloche
A small, transparent cover placed over plants to protect them from cold and pests. Learn more.
clone
Genetically identical individuals derived from a single ancestor by asexual reproduction. Learn more.
closed-loop system
A self-sustaining system in which waste is reused or recycled to minimize resource loss. Learn more.
clubroot
A soilborne disease of brassicas causing swollen, distorted roots and stunted plants. Learn more.
cold frame
A low, unheated enclosure that protects plants and extends the growing season. Learn more.
cold stratification
A pre-germination treatment that exposes seeds to a cold, moist period to break dormancy. Learn more.
cole crop
Brassica vegetables like cabbage, broccoli, and kale grown for edible leaves or buds. Learn more.
companion planting
Placing certain plants together to enhance growth, deter pests, or improve yield. Learn more.
compost bin
A container used to hold and manage organic waste during the composting process. Learn more.
compost tea
A liquid extract made by steeping compost to apply as a soil drench or foliar spray. Learn more.
composting
The controlled decomposition of organic matter into nutrient-rich soil amendment called compost. Learn more.
contouring
A landscaping technique aligning planting beds along land contours to reduce erosion. Learn more.
coppicing
Cutting trees or shrubs back to ground level to promote new shoots from the base. Learn more.
corn earworm
A moth larva that feeds on corn ears and other crops, causing direct kernel damage. Learn more.
cortex
A layer of tissue between the epidermis and vascular tissue, involved in storage and transport of nutrients. Learn more.
corymb
A flat-topped or slightly convex inflorescence in which lower flower stalks are longer than upper ones. Learn more.
cotyledon
The embryonic leaf in seed-bearing plants that often emerges first during germination. Learn more.
cover crop
A crop grown primarily to protect and enrich the soil rather than for harvest. Learn more.
crop rotation
The practice of alternating the types of crops grown in a specific area to maintain soil fertility and reduce pests. Learn more.
cross-pollination
The transfer of pollen between flowers of different plants, promoting genetic diversity and hybrid vigor. Learn more.
crossbreeding
The mating of plants from different varieties or species to combine desirable traits. Learn more.
crown rot
Fungal or bacterial decay of the crown area at the base of the plant, often leading to wilting and death. Learn more.
cucumber beetle
A small beetle that damages cucurbits by feeding on leaves and transmitting bacterial wilt. Learn more.
cucurbit downy mildew
A foliar disease of cucumbers and melons caused by Pseudoperonospora cubensis, producing yellow spots and mold. Learn more.
cultivar
A cultivated variety selected for distinct, heritable traits maintained by propagation. Learn more.
cultivars
a plant variety that has been produced through cultivation by selective breeding. Learn more.
cultivated
plants or soil maintained or prepared by humans for growing crops or ornamentals. Learn more.
cultural control
Pest management via horticultural practices such as crop rotation or sanitation. Learn more.
curly top virus
A viral disease transmitted by leafhoppers that causes leaf curling and stunted growth. Learn more.
cytospora canker
A fungal disease of woody plants leading to sunken cankers and branch dieback. Learn more.
D
damping-off
A fungal or oomycete disease causing seedlings to collapse near the soil line, often from Pythium or Rhizoctonia. Learn more.
defoliation
The loss or removal of leaves from a plant, caused by pests, disease, or weather. Learn more.
dehiscent
A fruit or organ that splits open when ripe to release its contents, such as seeds or spores. Learn more.
denitrification
A microbial process that converts nitrates (NO₃⁻) into nitrogen gas (N₂), resulting in nitrogen loss from soil. Learn more.
determinate/indeterminate
Growth habits describing whether a plant stops at a set size or continues to grow and flower. Learn more.
dew point
The temperature at which air becomes saturated and water vapor condenses into dew. Learn more.
disk flower
A small tubular flower located in the center of composite flower heads, such as in sunflowers. Learn more.
division
A propagation method that separates a mature plant into sections each with roots and shoots. Learn more.
dormancy
A period of minimal growth and metabolic activity allowing plants to survive unfavorable conditions. Learn more.
downy mildew
A group of plant diseases producing yellow leaf spots and fuzzy gray growth on the undersides; caused by oomycetes. Learn more.
drainage
The movement of water through soil; essential for preventing waterlogging and root diseases. Learn more.
drip irrigation
A water-efficient irrigation method that delivers water directly to plant roots through tubing and emitters. Learn more.
drip line
The outermost circumference of a tree’s canopy where water drips from the leaves to the ground. Learn more.
drought
a prolonged period of deficient rainfall that reduces soil moisture and plant growth. Learn more.
drought tolerance
The ability of a plant to maintain function under limited water availability. Learn more.
drupe
A fleshy fruit with a single hard stone enclosing the seed, such as a cherry or peach. Learn more.
dutch elm disease
A vascular wilt disease of elms spread by bark beetles and caused by Ophiostoma fungi. Learn more.
E
early blight (tomato/potato)
A fungal disease caused by Alternaria species, producing concentric ring lesions on leaves and stems. Learn more.
earthworm casting
Nutrient-rich material produced by earthworms that enhances soil structure and fertility. Learn more.
earwig
Nocturnal insects that feed on decaying material and occasionally damage flowers and seedlings. Learn more.
ecological footprint
A measure of the environmental impact of human activities expressed in terms of land and resource use. Learn more.
ecosystem resilience
The ability of an ecosystem to recover from disturbances while maintaining its functions and structure. Learn more.
ecosystem restoration
The process of assisting the recovery of degraded ecosystems through active management and replanting. Learn more.
ecosystem services
The benefits humans derive from natural ecosystems, such as pollination, nutrient cycling, and water purification. Learn more.
ecotone
A transition area between two biological communities, where species from both ecosystems may coexist. Learn more.
edaphology
The study of how soils influence living things, particularly plants and agriculture. Learn more.
edging
Creating defined boundaries between lawn, beds, or paths for aesthetics and maintenance. Learn more.
edible landscaping
The integration of food-producing plants into ornamental garden designs for both beauty and function. Learn more.
eluviation
The process by which dissolved or suspended materials are removed from one soil horizon to another below. Learn more.
endodermis
The innermost layer of the cortex in plant roots that regulates water and nutrient flow into the vascular cylinder. Learn more.
endophyte
an organism, often a fungus or bacterium, that lives inside a plant without causing harm. Learn more.
ephemeral
A plant with a very short life cycle, often germinating, flowering, and dying within a few weeks. Learn more.
epidermis
The outermost layer of cells covering leaves, stems, and roots, serving as a protective barrier. Learn more.
eriophyid
tiny plant-feeding mites with only four legs, often host-specific and causing galls or leaf distortion. Learn more.
erosion
The process by which soil and rock are removed from the Earth’s surface by wind, water, or human activity. Learn more.
evaporative cooling
A cooling method using water evaporation to reduce air temperature inside a greenhouse. Learn more.
excurrent
Having a main trunk or stem that grows more strongly than the side branches, forming a conical shape. Learn more.
F
fibrous root
A root system made up of many thin, moderately branching roots growing from the stem base. Learn more.
field capacity
The amount of soil moisture remaining after excess water has drained away. Learn more.
fire blight
A bacterial disease of apples, pears, and related plants that blackens blossoms and shoots. Learn more.
flea beetle
Small, jumping beetles that chew small round holes in leaves of many vegetable crops. Learn more.
floral formula
A symbolic representation of the structure of a flower using letters, numbers, and symbols. Learn more.
floral morphology
The study of the structure and form of flowers and their reproductive organs. Learn more.
floriculture
The branch of horticulture concerned with the cultivation of flowering and ornamental plants. Learn more.
foliar feed
Applying nutrients to plant leaves in solution for absorption through foliage. Learn more.
food web
A complex network of interconnected food chains representing feeding relationships in an ecosystem. Learn more.
forcing
Inducing plants to grow or flower out of their natural season with environmental controls. Learn more.
forest gardening
A sustainable, multi-layered food production system modeled after a natural forest ecosystem. Learn more.
french drain
A gravel-filled trench with perforated pipe to redirect surface and groundwater. Learn more.
frost injury
Tissue damage in plants resulting from freezing temperatures that rupture cell walls. Learn more.
fruit fly
Small flies whose larvae feed within fruit; includes agricultural pests such as Drosophila and Ceratitis. Learn more.
fumigation
Application of gaseous pesticides to control soilborne or stored-product pests. Learn more.
fungus gnat
Tiny flies whose larvae feed on organic matter and roots in moist potting soil. Learn more.
fusarium wilt
Soilborne fungal disease causing yellowing and vascular browning in many crops. Learn more.
G
gall
Abnormal plant growths caused by insects, mites, fungi, or bacteria that result in swelling or distortion of tissues. Learn more.
gall wasp
Tiny wasps that lay eggs in plant tissues, producing characteristic galls, especially on oaks. Learn more.
Garden design
The art and process of creating functional and aesthetic outdoor planting spaces. Learn more.
Garden journal
A record kept by gardeners documenting planting dates, conditions, and observations. Learn more.
genotype
The genetic makeup of an organism that determines its hereditary potential and characteristics. Learn more.
geotextile
A permeable fabric used in landscaping to separate soil layers and prevent weed growth. Learn more.
germination
The process by which a seed begins growth into a seedling under suitable conditions. Learn more.
germination rate
The percentage of seeds that successfully sprout under specific conditions, used as a measure of seed viability. Learn more.
gibberellin
A class of plant hormones that stimulate stem elongation, germination, and flowering. Learn more.
girdling
Damage that removes bark around the circumference of a stem, interrupting nutrient flow and often killing the plant. Learn more.
girdling root
A root that encircles the trunk or other roots, restricting growth and transport. Learn more.
grasshopper
Chewing insects that feed on leaves and stems, occasionally causing severe defoliation. Learn more.
green manure
Crops grown specifically to be incorporated into the soil to add organic matter and nutrients. Learn more.
green roof
A vegetated roof system that improves insulation, absorbs rainwater, and supports urban biodiversity. Learn more.
greenfly
Common name for green-colored aphids that infest soft shoots and transmit viruses. Learn more.
grey mold
Another term for Botrytis cinerea, a fungal disease producing fuzzy gray growth on decaying tissues. Learn more.
greywater
Wastewater from sinks or showers that can be reused for irrigation after treatment. Learn more.
greywater recycling
The reuse of lightly used household water (from sinks, showers, etc.) for irrigation or flushing. Learn more.
groundwater
Water located beneath the Earth’s surface in soil pore spaces and rock formations. Learn more.
guava wilt
A fungal disease of guava trees caused by Fusarium oxysporum, leading to yellowing and wilting. Learn more.
gummosis
Exudation of sticky sap or gum from bark, often caused by fungal infection or mechanical injury. Learn more.
gypsy moth
A defoliating moth (Lymantria dispar) whose caterpillars feed on the foliage of many tree species. Learn more.
H
habitat fragmentation
The process by which large habitats are broken into smaller, isolated patches, often due to human activity. Learn more.
habitat restoration
The process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed. Learn more.
hardening off
Gradually acclimating seedlings to outdoor conditions before transplanting. Learn more.
hardiness zone
A geographic zone defined by minimum temperatures to guide plant selection. Learn more.
heat mat
An electric mat used to gently warm soil or trays to improve seed germination and root growth. Learn more.
heirloom
A cultivar maintained through open pollination over generations, often valued for heritage traits. Learn more.
heirloom seed
A traditional seed variety passed down through generations, often open-pollinated and non-hybridized. Learn more.
hermaphrodite
A plant or flower possessing both male (stamens) and female (carpels) reproductive organs. Learn more.
heterosis (hybrid vigor)
The improved or increased function of hybrid offspring compared to parents, often seen in growth or yield. Learn more.
homologous
Structures sharing a common evolutionary origin, even if functionally different. Learn more.
hornworm
the caterpillar stage of the hawk or sphinx moth, recognizable by a horn-like projection on its tail end. Learn more.
horticulture therapy
The use of gardening and plant-related activities for therapeutic purposes. Learn more.
hügelkultur
A raised bed technique built over woody debris to enhance moisture retention and fertility. Learn more.
humidity dome
A clear plastic cover placed over seed trays to maintain high humidity for germination. Learn more.
humus
Stable, decomposed organic material that contributes to soil structure and fertility. Learn more.
hybrid
Progeny from crossing different varieties or species, often denoted as F1 in cultivation. Learn more.
hybridization
The process of crossing different species or varieties to produce hybrid offspring with specific traits. Learn more.
hypanthium
A floral structure formed by the fusion of the basal parts of the calyx, corolla, and stamens. Learn more.
hypocotyl
The stem portion of a germinating seedling below the cotyledons and above the root. Learn more.
I
illuviation
The accumulation of leached materials such as clay, iron, or organic matter into a lower soil horizon. Learn more.
indeterminate growth
Growth that is not genetically limited, continuing throughout the life of the plant. Learn more.
insect gall
Plant swelling or deformation caused by insect activity such as egg laying or feeding, often species-specific. Learn more.
insecticidal soap
A mild pesticide made from potassium salts of fatty acids, used to control soft-bodied pests like aphids and mites. Learn more.
integrated farming
A system that combines crop and livestock production to maximize efficiency and reduce waste. Learn more.
integrated nutrient management
The balanced use of organic and inorganic fertilizers to sustain soil fertility and productivity. Learn more.
integrated pest management (ipm)
A sustainable pest control strategy combining biological, cultural, mechanical, and chemical methods. Learn more.
invasive species
Non-native organisms that spread rapidly and harm ecosystems or economies. Learn more.
J
K
keyhole garden
A raised bed with a central compost basket for watering and nutrient cycling. Learn more.
L
late blight (potato/tomato)
A devastating disease caused by Phytophthora infestans, leading to dark lesions and rapid plant collapse. Learn more.
lawn aerator
A device used to perforate the soil with small holes to allow air, water, and nutrients to reach roots. Learn more.
layering
A propagation method where a stem forms roots while still attached to the parent plant. Learn more.
leachate
Liquid that drains through soil or compost, carrying dissolved materials, nutrients, or pollutants. Learn more.
leaching zone
The upper layer of soil where minerals and nutrients are dissolved and carried downward by water. Learn more.
leaf blight
Rapid browning and death of leaf tissue caused by fungi, bacteria, or environmental stress. Learn more.
leaf miner
The larva of various insects that tunnels between leaf layers, creating visible trails. Learn more.
leaf mold
A fungal disease or composted leaf product; in tomatoes, it refers to Passalora fulva infection. Learn more.
leaf roll virus
Viral diseases of crops like potatoes and grapes that cause upward leaf curling and yield loss. Learn more.
leaf spot
Circular necrotic lesions on leaves caused by fungi or bacteria, often surrounded by yellow halos. Learn more.
leafminer
insect larvae that live between leaf surfaces, feeding on internal tissues and creating tunnels or blotches. Learn more.
legume
A pod-type fruit characteristic of the pea family that splits open along two seams. Learn more.
light intensity
The amount of light energy received per unit area, influencing photosynthesis and plant growth rate. Learn more.
lime (agricultural)
Calcium-containing materials applied to raise soil pH and reduce acidity. Learn more.
living mulch
A low-growing ground cover planted under crops to suppress weeds and retain moisture. Learn more.
locule
A small cavity or compartment within an organ, such as the chambers of an ovary or anther. Learn more.
lodicule
Small scale-like organs at the base of the ovary in grass flowers that aid in flower opening. Learn more.
looper
a caterpillar that moves in looping motions due to missing middle legs, such as inchworms. Learn more.
lygus bug
A group of plant bugs (Lygus spp.) that feed on developing buds and fruit, causing deformation. Learn more.
M
macro-nutrients (plants)
Essential elements required in larger amounts, typically N, P, K, Ca, Mg, and S. Learn more.
magnesium deficiency
A nutrient deficiency causing yellowing between leaf veins, common in tomatoes and citrus. Learn more.
mealybug
Small, white, cottony insects that suck sap from stems and leaves, often secreting honeydew. Learn more.
membranous
having a thin, parchment-like texture; often describing plant or insect tissue. Learn more.
microclimate
A localized climate that differs from the surrounding area, influenced by vegetation, terrain, or structures. Learn more.
micronutrients (plants)
Essential elements required in trace amounts such as Fe, Mn, Zn, Cu, B, Mo, and Cl. Learn more.
microspore
The smaller of two kinds of spores produced by seed plants, developing into male gametophytes. Learn more.
midrib/midvein
the central vein of a leaf that supports and transports water and nutrients. Learn more.
mildew
A common fungal disease characterized by white or gray powdery growth on leaf surfaces. Learn more.
minimal tillage
A soil conservation practice that reduces plowing to preserve structure and microbial life. Learn more.
mixed cropping
The practice of growing two or more crops simultaneously in the same field for better resource use. Learn more.
mold
A broad term for various filamentous fungi that decompose organic matter, sometimes pathogenic to plants. Learn more.
monocotyledon
A flowering plant with one cotyledon in the seed, such as grasses and lilies. Learn more.
monoculture
The agricultural practice of growing a single crop species in a field over a large area, often reducing biodiversity. Learn more.
mosaic disease (tobacco)
A viral disease of tobacco and related plants that causes mottled leaves and stunted growth. Learn more.
mosaic virus (plants)
A group of viruses causing mottled leaf patterns and stunted growth. Learn more.
moth caterpillar
The larval stage of moths that may feed on leaves, buds, or fruit depending on species. Learn more.
mucilage
A gelatinous substance produced by some plants that aids in water retention or seed germination. Learn more.
mulch
Material applied to the soil surface to conserve moisture, suppress weeds, and moderate temperature. Learn more.
mulch volcano
An improper mulching technique in which mulch is piled high against a tree trunk, potentially causing decay. Learn more.
mulching
The use of organic or inorganic material spread over soil to retain moisture, suppress weeds, and regulate temperature. Learn more.
multiple fruit
A fruit formed from the ovaries of several flowers growing in a cluster, such as a pineapple. Learn more.
mummy rot
A fungal infection that desiccates and hardens infected fruits, often overwintering as ‘mummies.’ Learn more.
mutation
A change in the DNA sequence that can lead to genetic variation and potentially new traits. Learn more.
mutualism
A symbiotic relationship in which both organisms benefit, such as pollinators and flowers. Learn more.
mycelium
The vegetative network of fungal filaments (hyphae) that spread through soil or tissue. Learn more.
mycorrhiza
A mutualistic association between plant roots and fungi that enhances nutrient uptake. Learn more.
mycorrhizal imbalance
A disruption in the symbiotic relationship between roots and beneficial fungi, often caused by soil disturbance or chemical fertilizers. Learn more.
N
n-p-k
Shorthand for the primary plant nutrients nitrogen, phosphorus, and potassium in fertilizers. Learn more.
native seed mix
A blend of locally adapted plant species for habitat restoration or naturalized gardens. Learn more.
natural pest control
The use of beneficial insects, birds, or companion planting to manage pest populations without synthetic chemicals. Learn more.
necrosis
The death of plant tissue, often appearing as brown or blackened patches on leaves, stems, or fruit. Learn more.
nematode
Microscopic roundworms; some species are plant parasites while others are beneficial. Learn more.
nematode (plant-parasitic)
Microscopic roundworms that feed on plant roots, causing galls, stunted growth, and yield loss. Learn more.
niche
The role and position of an organism within its environment, including its interactions with other species. Learn more.
nitrogen deficiency
A nutrient imbalance causing uniform yellowing of older leaves and reduced plant vigor. Learn more.
no-till gardening
A soil conservation method that avoids turning the soil, preserving structure and beneficial organisms. Learn more.
nursery pot
A reusable plastic or biodegradable container used for growing and selling plants. Learn more.
nymphs
immature forms of insects that resemble adults but lack fully developed wings or reproductive organs. Learn more.
O
oblanceolate
Reverse of lanceolate; broadest above the middle and tapering toward the base. Learn more.
oedema (edema)
Swelling or blistering of leaves due to excessive water uptake and poor transpiration. Learn more.
oomycete
Fungus-like microorganisms responsible for diseases such as downy mildew and root rot. Learn more.
open-pollinated
Plants pollinated by natural mechanisms, producing offspring true to type if isolated. Learn more.
organic certification
A process verifying that food or products are produced according to organic farming standards. Learn more.
organic matter
Decomposed plant or animal residues that improve soil fertility and structure. Learn more.
organic mulch
Mulch derived from plant or animal materials such as leaves, straw, or bark. Learn more.
overseeding
Sowing seed into existing turf to thicken coverage or introduce new varieties. Learn more.
overwinters
the ability of an organism or plant to survive through the winter season in a dormant or protected state. Learn more.
oxalate/oxalic acid
a naturally occurring acid in plants; high concentrations can be toxic. Learn more.
P
palmate
having leaflets or veins radiating from a single point like the fingers of a hand. Learn more.
pappus
A tuft of hairs or bristles attached to the seed of many members of the daisy family, aiding in dispersal. Learn more.
par (photosynthetically active radiation)
The portion of the light spectrum (400–700 nm) used by plants for photosynthesis. Learn more.
parasites
organisms that live on or within another organism (the host) and obtain nutrients from it. Learn more.
parasitic
relating to an organism that depends on a host for nourishment, often harming it. Learn more.
parenchyma
Fundamental plant tissue composed of living, thin-walled cells functioning in photosynthesis, storage, and regeneration. Learn more.
pathogen
Any organism such as a virus, bacterium, or fungus that causes disease in plants. Learn more.
peach leaf curl
A fungal disease of peaches and nectarines causing distorted, reddened leaves and reduced yield. Learn more.
pedology
The branch of soil science that studies the formation, classification, and mapping of soils in their natural environment. Learn more.
peony botrytis blight
A Botrytis infection of peony causing blackened buds and stems in cool, wet weather. Learn more.
perennial
A plant that lives for more than two years, often flowering annually once mature. Learn more.
perfect flower
A flower containing both stamens and carpels (male and female reproductive organs). Learn more.
permaculture
A design system for sustainable living and agriculture modeled after natural ecosystems. Learn more.
permeable paving
Paving materials designed to allow water to infiltrate into the ground, reducing stormwater runoff. Learn more.
persistent
Remaining attached instead of falling off, as in leaves or sepals that stay on the plant. Learn more.
petiole
The stalk that connects a leaf blade to the stem, supporting leaf orientation for light capture. Learn more.
ph (soil)
A measure of soil acidity or alkalinity influencing nutrient availability and microbial activity. Learn more.
phenotype
The observable physical and physiological traits of an organism, determined by genotype and environment. Learn more.
pheromone
a chemical signal released by an organism to influence the behavior of others of the same species. Learn more.
phloem fiber
Long, thick-walled sclerenchyma fibers associated with the phloem that provide mechanical support. Learn more.
photoperiod
The length of day and night that influences flowering and vegetative growth in plants. Learn more.
photoperiodism
Physiological responses of plants to the relative lengths of day and night. Learn more.
photosynthesis
The process by which plants convert light energy into chemical energy in the form of sugars. Learn more.
photovoltaic irrigation
The use of solar panels to power water pumps for energy-efficient irrigation. Learn more.
phyllody
A plant disease symptom in which floral parts become leaf-like, often caused by phytoplasmas. Learn more.
phytophthora root rot
Root and crown rots caused by Phytophthora species in poorly drained soils. Learn more.
phytoplasma disease
Diseases caused by wall-less bacteria that inhabit phloem tissue, transmitted by leafhoppers. Learn more.
pistil
The female reproductive organ of a flower, consisting of the stigma, style, and ovary. Learn more.
plant hardiness
The ability of a plant to survive adverse conditions such as cold or drought. Learn more.
plug (horticulture)
A small, individual seedling grown in a cell for efficient handling and transplanting. Learn more.
pollard
A pruning system where upper branches are cut back to promote a dense head of regrowth. Learn more.
pollen
Microscopic grains produced by anthers that contain male gametes for fertilization. Learn more.
pollinator
Any animal or agent that transfers pollen from the male to the female structures of flowers. Learn more.
pollinator corridor
A continuous habitat that supports bees, butterflies, and other pollinators across landscapes. Learn more.
polyploidy
The condition of having more than two complete sets of chromosomes, common in many plant species. Learn more.
potassium
An essential plant macronutrient involved in water regulation and enzyme activation. Learn more.
powdery mildew
A fungal disease that produces a white, powdery coating on leaves, stems, and flowers. Learn more.
powdery scab (potato)
A disease of potato tubers causing corky lesions and vectoring powdery scab pathogens. Learn more.
prop root
Aerial root that provides additional support to the stem, as in corn or banyan trees. Learn more.
propagation by tissue culture
A method of cloning plants under sterile laboratory conditions using small pieces of tissue. Learn more.
protandry
The condition in which the male parts of a flower mature before the female parts, reducing self-pollination. Learn more.
protogyny
The condition in which the female parts of a flower mature before the male parts. Learn more.
pupa
the nonfeeding, often immobile, transformation stage between larva and adult in insects with complete metamorphosis. Learn more.
Q
quarantine (plants)
Isolating new or diseased plants to prevent spread of pests or pathogens. Learn more.
quick composting
Managing moisture, aeration, and carbon-to-nitrogen ratio to accelerate decomposition. Learn more.
R
rain garden
A landscaped area designed to collect and absorb stormwater runoff from roofs or paved areas. Learn more.
rainwater harvesting
The collection and storage of rainwater for landscape irrigation and other uses. Learn more.
raised row
A gardening method using slightly elevated rows to improve drainage and soil warmth. Learn more.
receptacle
The part of a flower that supports the floral organs; in fruits, it may form edible tissue. Learn more.
regenerative agriculture
A holistic approach to farming that restores soil health, biodiversity, and ecosystem function. Learn more.
renewable energy
Energy derived from sources that are naturally replenished, such as solar, wind, or hydropower. Learn more.
rhizosphere microbiome
The community of microorganisms living in the soil closely associated with plant roots. Learn more.
ring spot virus
A viral disease causing circular chlorotic or necrotic patterns on leaves or fruit. Learn more.
rock garden
A garden designed with rocks and alpine plants adapted to well-drained conditions. Learn more.
rodent damage
Physical injury to plant roots, bark, or stems caused by gnawing mammals such as voles or mice. Learn more.
root ball
The mass of roots and adhering growing medium when a plant is removed from its container. Learn more.
root hair
A tiny hairlike outgrowth on a root that increases surface area for absorption. Learn more.
root maggot
The larval stage of certain flies that feed on plant roots, causing stunted growth or wilting. Learn more.
root rot
A condition where roots decay due to overwatering or soilborne fungi such as Pythium and Phytophthora. Learn more.
rosette
a circular cluster of leaves radiating from a central stem near the ground surface. Learn more.
runner
A horizontal stem or stolon that grows along the ground and produces new plants at its nodes. Learn more.
rust (fungal disease)
A common fungal infection producing orange or brown pustules on leaves and stems. Learn more.
S
sandy soil
Soil dominated by large particles with rapid drainage and low nutrient-holding capacity. Learn more.
sanitation
the removal or destruction of diseased plant material and contaminated tools to prevent spread. Learn more.
scab
A plant disease causing rough, corky lesions on fruit, leaves, or tubers, often fungal in origin. Learn more.
scale insect
Small, immobile insects that attach to plant stems and leaves, feeding on sap and excreting honeydew. Learn more.
scarification (seed)
Physically or chemically weakening a seed coat to encourage germination. Learn more.
sclerenchyma
Strengthening plant tissue with thick, lignified cell walls that provide rigidity to stems and leaves. Learn more.
sclerotinia rot (white mold)
A fungal disease producing cottony white growth and black sclerotia on stems and fruit. Learn more.
seed dormancy
A state in which viable seeds fail to germinate until specific conditions are met. Learn more.
selection
The process of choosing plants with desired traits for breeding or cultivation. Learn more.
self-pollination
Fertilization of a flower by its own pollen, ensuring genetic uniformity in offspring. Learn more.
self-watering container
A planter with a reservoir that supplies water to the soil via capillary action. Learn more.
septoria leaf spot
A fungal disease causing small, dark-bordered spots on leaves of tomato and other crops. Learn more.
shade cloth
Fabric used to reduce sunlight and heat for plants in greenhouses or outdoor beds. Learn more.
shade house
A structure covered with shade cloth that reduces sunlight exposure for delicate or shade-loving plants. Learn more.
sheaths
tubular structures that encase or protect other plant organs, such as leaf bases. Learn more.
sheet mulching
A layering technique using cardboard and organic matter to smother weeds and build soil. Learn more.
shepherds crook
a curved symptom of shoots resembling the handle of a cane, often from disease. Learn more.
silique
An elongated seed capsule that splits open when mature, typical of the mustard family. Learn more.
slug
Soft-bodied mollusks that feed on leaves and seedlings, leaving slime trails and irregular holes. Learn more.
smut
A group of fungal diseases that produce black, powdery spores on cereals and grasses. Learn more.
soil
The natural medium for plant growth composed of minerals, organic matter, water, and air. Learn more.
soil carbon
The carbon stored in soil organic matter, vital for fertility and climate regulation. Learn more.
soil compaction
Compression of soil that reduces pore space, limiting air and water movement. Learn more.
soil health
The continued capacity of soil to function as a living ecosystem that sustains plants, animals, and humans. Learn more.
soil horizon
A distinct layer of soil with specific physical and chemical characteristics, forming part of a soil profile. Learn more.
soil organic matter
The organic fraction of soil derived from decomposed residues and organisms. Learn more.
soil profile
The vertical section of soil showing all its horizons, revealing structure, texture, and composition. Learn more.
soil structure
The arrangement of soil particles into aggregates influencing porosity and root growth. Learn more.
soil taxonomy
The system used to classify soils based on their physical, chemical, and biological properties. Learn more.
soil test
Analytical assessment of soil properties to guide fertilization and amendments. Learn more.
soil texture
The proportion of sand, silt, and clay in soil, determining water retention and aeration. Learn more.
solarization (soil)
Using clear plastic to trap solar heat and reduce soilborne pests and weeds. Learn more.
sooty blotch and flyspeck
A complex of superficial fungal blemishes on apple fruit surfaces. Learn more.
sooty mold
Black fungal growth that develops on honeydew deposits from aphids and scale insects. Learn more.
spider mite
Tiny arachnids that feed on plant sap, causing stippling, webbing, and leaf discoloration. Learn more.
spore
A reproductive unit capable of developing into a new organism without fusion with another cell. Learn more.
spores
reproductive cells produced by fungi, ferns, and some plants capable of developing into a new organism. Learn more.
sprinkler irrigation
Applying water to crops by spraying it into the air and letting it fall like rain. Learn more.
stem rot
Fungal infection causing decay at the base or crown of plants, leading to collapse. Learn more.
stippling
tiny pale or yellow spots on leaves caused by piercing-sucking insects like mites or leafhoppers. Learn more.
stolon (runner)
A horizontal stem that grows along the surface and produces new plants at nodes. Learn more.
stratification (seed)
Exposing seeds to moist chilling or other conditions to break dormancy. Learn more.
style
The slender stalk of the pistil connecting the stigma to the ovary, guiding pollen tubes. Learn more.
succession (ecology)
The gradual process of change in species composition and community structure over time. Learn more.
sucker (plant)
A shoot arising from a plant’s root system or base, often removed to direct growth. Learn more.
sustainable agriculture
Farming that meets current food needs without compromising the environment or future generations. Learn more.
sustainable yield
The level of resource harvest that can be maintained without degrading the ecosystem. Learn more.
systemic
referring to a substance or infection that moves internally through plant tissues. Learn more.
T
taxonomy (plants)
The classification of plants into hierarchical groups based on relationships. Learn more.
thallus
A plant body not differentiated into root, stem, and leaves, as in algae or lichens. Learn more.
thermal composting
A controlled composting process using high temperatures to accelerate decomposition and kill pathogens. Learn more.
thermal mass
Materials that absorb and store heat energy during the day and release it slowly at night to stabilize temperatures. Learn more.
thinning (plants)
Removing excess seedlings or branches to reduce competition and improve growth. Learn more.
thrips
Minute insects that feed by rasping and sucking, causing silvered patches on leaves and deformed flowers. Learn more.
toxin
a naturally occurring poison produced by living organisms such as plants, fungi, or bacteria. Learn more.
transplant shock
Physiological stress experienced by plants after moving to a new location. Learn more.
trophic level
The position an organism occupies in a food chain, such as producer, consumer, or decomposer. Learn more.
U
underplanting
Planting low-growing species beneath taller plants to fill space and suppress weeds. Learn more.
urban farming
The practice of cultivating, processing, and distributing food in or around cities. Learn more.
USDA Plant Hardiness Map
A map of minimum winter temperatures used to guide plant selection. Learn more.
V
vascular bundle
A strand of xylem and phloem tissues that transport water, nutrients, and sugars throughout the plant. Learn more.
vascular plant
A plant with specialized tissue (xylem and phloem) for transporting fluids. Learn more.
ventilation rate
The frequency at which air is exchanged in a greenhouse, controlling temperature, humidity, and CO₂ levels. Learn more.
vermiculite
Expanded mica used to increase water retention and aeration in potting media. Learn more.
vernalization
Exposure to a period of cold required by some plants to initiate flowering. Learn more.
verticillium dahliae
A species causing Verticillium wilt in many woody and herbaceous plants. Learn more.
verticillium wilt
A soilborne fungal disease that clogs vascular tissue, leading to leaf yellowing and plant death. Learn more.
virus
Microscopic pathogens that invade plant cells, often spread by insects, causing mottling or stunting. Learn more.
virus (plant)
A pathogenic agent causing systemic or localized disease symptoms in plants. Learn more.
virus indexing
Testing plant material to ensure it is free from specific viruses before propagation. Learn more.
viruses
plural of virus; infectious agents composed of genetic material within a protein coat. Learn more.
W
water conservation
Strategies and technologies used to reduce water usage and waste in gardening and agriculture. Learn more.
water infiltration
The process by which water enters and moves downward through the soil surface. Learn more.
watershed
An area of land that drains all rainfall and runoff into a common outlet such as a river or lake. Learn more.
whitefly
Small, sap-sucking insects that excrete honeydew and transmit plant viruses, common in greenhouses. Learn more.
whorl
a circular arrangement of three or more leaves, petals, or other organs at the same node. Learn more.
winter sowing
Sowing seeds outdoors in covered containers during winter for natural stratification. Learn more.
X
xeriscaping
Landscaping designed to reduce or eliminate the need for irrigation, common in arid regions. Learn more.
xylem ray
Radial sheets of parenchyma cells in xylem that transport water and nutrients laterally within stems. Learn more.
Y
yellowing (chlorosis)
A symptom of nutrient deficiency, waterlogging, or disease leading to pale or yellow leaves. Learn more.
yield gap
The difference between potential and actual crop yields due to environmental or management factors. Learn more.
Z
zero tillage
Crop or garden establishment without prior soil tillage to conserve structure and moisture. Learn more.
zero waste gardening
A gardening philosophy that minimizes waste through composting, reuse, and efficient resource use. Learn more.
zonate leaf spot
A fungal disease forming concentric ring patterns on leaves, characteristic of Gloeocercospora sorghi. Learn more.
zone (hardiness)
A classification based on minimum temperatures to indicate plant survivability. Learn more.