World Food Crops Glossary
Note to Students
Please let me know if there are words used in the course that you think
should be included in this glossary! kimberly@oregonstate.edu
Sources
Garden Web Glossary of Botanical Terms http://glossary.gardenweb.com/glossary/
Glossary of Crop Science Terms, Crop Science Society of America
http://www.crops.org/cropgloss/
International Rice Research Institute. A Glossary of Rice Terminology
http://www.knowledgebank.irri.org/glossary/whnjs.htm
Levetin
and McMahon. 2003. Plants and Society. 3rd edition. McGraw-Hill, New
York, NY.
http://highered.mcgraw-hill.com/sites/dl/free/0072909498/57896/glossary.pdf
Lumpkin, T.A. 1995. WORLD CROPS lab manual, Washington State University
Schlegel, R. Plant Breeding Updates http://www.desicca.de/plant_breeding/
Schlindwein, B. A Hypermedia Glossary of Genetic Terms. http://www.weihenstephan.de/~schlind/genglos.html
University of California, Berkeley, Museum of Paleontology. Glossary.
http://www.ucmp.berkeley.edu/glossary/glossary.html
World Resources Institute. Biodiversity Glossary of Terms.
http://www.wri.org/wri/biodiv/gbs-glos.html
Directory of Genetics Glossaries
Glossaries of Genome / Human Genetics Terms http://www.kumc.edu/gec/glossary.html
A
- Accession
- A sample of a crop variety collected at a specific location and time;
may be of any size.
- Adaptation
- A genetically determined characteristic that enhances an organism's
ability to cope with its environment.
- Agrobiodiversity
- The diversity of plants, animals, and ecologies found in agricultural systems
- Alien species
- A species occurring in an area outside of its historically known natural
range as a result of intentional or accidental dispersal by human activities.
Also known as introduced species.
- Allele
- One of several forms of the same gene.
- Alternation of Generations
- Alternation between a haploid gametophyte phase and a diploid sporophyte
phase in the life cycle of sexually reproducing organisms.
- Aneuploid
- Having one more or less than the normal, euploid number of chromosomes.
- Anther
- Male reproductive structure that produces pollen.
- Anthesis
- The time of flowering or pollination.
- Asexual Reproduction
- Any form of reproduction not involving the union of gametes.
- Auricles
- Finger-like projections that grow out from the opposite corners of
the collar and are important in the identification of grasses.
- Awn
- A slender appendage found on the end or back of the lemma.
- Axillary Tillers
- The tillers that emerge from the leaf axils.
B
- Biodiversity
- The totality of genes, species, and ecosystems in a region or the
world.
- Biogeography
- The scientific study of the geographic distribution of organisms.
- Biological Resources
- Those components of biodiversity of direct, indirect, or potential
use to humanity. (Used interchangeably with "Biotic Resources")
- Biome
- A major portion of the living environment of a particular region (such
as a fir forest or grassland), characterized by its distinctive vegetation
and maintained by local climatic conditions.
- Bioregion
- A territory defined by a combination of biological, social, and geographic
criteria, rather than geopolitical considerations; generally, a system
of related, interconnected ecosystems.
- Biota
- All of the organisms, including animals, plants, fungi, and microorganisms,
found in a given area.
- Biotechnology
- Any technique (e.g., recombinant DNA methods, protein engineering,
cell fusion, nucleotide synthesis, biocatalysis, fermentation, cell
cultures, cell manipulations etc.) that uses living organisms or parts
of them to make or modify products, to improve organisms or to make
them available for specific uses.
- Biotic
- Pertaining to any aspect of life, especially to characteristics of
entire populations or ecosystems.
- Blade
- The flat expanded portion of a leaf.
- Bracts
- Special modified leaves found in monocot inflorescences that replace
the calyx and corolla.
- Buffer zone
- The region near the border of a protected area; a transition zone
between areas managed for different objectives.
C
- Calyx
- A collective term that refers to all the sepals together.
- Carrying Capacity
- The maximum number of people, or individuals of a particular species,
that a given part of the environment can maintain indefinitely.
- Caryopsis
- The one-seeded dry fruit of grasses in which the testa and pericarp
are completely fused and inseparable at maturity.
- Center of Diversity
- Geographic region with high levels of genetic or species diversity.
- Center of Endemism
- Geographic region with numerous locally endemic species.
- Central dogma of biology
- DNA from alleles at a genetic locus translates into proteins.
- Characteristic Diversity
- The pattern of distribution and abundance of populations, species,
and habitats under conditions where humanity's influence on the ecosystem
is no greater than that of any other biotic factor.
- Chiasmata
- The x-shaped configuration formed by two chromatids of homologous
chromosomes as they remain attached to each other during prophase I
of meiosis.
- Chromatid
- One of the two strands of a chromosome; they are united by a centromere.
- Class
- In taxonomy, a category just beneath the phylum and above the order;
a group of related, similar orders.
- Climax Community
- The end of a successional sequence; a community that has reached stability
under a particular set of environmental conditions.
- Cline
- Change in population characteristics over a geographical area, usually
related to a corresponding environmental change.
- Clone
- A population of individuals all derived asexually from the same single
parent.
- Coleoptile
- Protective structures found in monocot seeds that cover the embryonic
shoot bud or plumule
- Coleorhiza
- Protective structures found in monocot seeds that cover the embryonic
root
- Coleoptilar Tiller
- The tiller that emerges from the coleoptilar node.
- Collar
- The junction of the leaf blade with the sheath.
- Co-management
- The sharing of authority, responsibility, and benefits between government
and local communities in the management of natural resources.
- Common Property Resource Management
- The management of a specific resource (such as a forest or pasture)
by a well-defined group of resource users with the authority to regulate
its use by members and outsiders.
- Community
- An integrated group of species inhabiting a given area; the organisms
within a community influence one another's distribution, abundance,
and evolution. (A Human Community is a social group of any size whose
members reside in a specific locality.)
- Comparative Advantage
- Relative superiority with which a region or state may produce a good
or service.
- Complete Flower
- A flower that has all essential and accessory components.
- Compound Leaf
- A leaf composed of leaflets; the arrangement of the leaflets on the
petiole can be either palmate, all the leaflets attached at the same
point at the end of the petiole, or pinnate, the leaflets attached along
the longitudinal axis of the petiole.
- Conservation
- The management of human use of the biosphere so that it may yield
the greatest sustainable benefit to current generations while maintaining
its potential to meet the needs and aspirations of future generations:
Thus conservation is positive, embracing preservation, maintenance,
sustainable utilization, restoration, and enhancement of the natural
environment.
- Conservation of Biodiversity
- The management of human interactions with genes, species, and ecosystems
so as to provide the maximum benefit to the present generation while
maintaining their potential to meet the needs and aspirations of future
generations; encompasses elements of saving, studying, and using biodiversity.
- Corm
- The enlarged fleshy base of a stem, bulb-like but solid.
- Corolla
- A collective term that refers to all the petals together.
- Cortex
- the region of a stem or root surrounding the vascular cylinder but
inside the epidermis. Undifferentiated loosely packed cells that can
function as storage tissues.
- Cosmopolitan
- Widely distributed over the globe.
- Cotyledon
- An embryo leaf that usually serves as the major food reserve for dicot
seedlings May absorb food for seedling growth
- Crossing-over
- The exchange of corresponding segments of chromatids between homologous
chromosomes during prophase I of meiosis.
- Crown
- Several nodes whose internodes do not elongate at the junction of
the stem and the root.
- Cryogenics
- The branch of physics relating to the effects and production of very
low temperatures; as applied to living organisms, preservation in a
dormant state by freezing, drying, or both.
- Cultivar
- A cultivated variety (genetic strain) of a domesticated crop plant.
- Cultural diversity
- Variety or multiformity of human social structures, belief systems,
and strategies for adapting to situations in different parts of the
world.
D
- Decomposition
- The breakdown of organic materials by organisms in the environment,
releasing energy and simple organic and inorganic compounds.
- Demography
- The rate of growth and the age structure of populations, and the processes
that determine these properties.
- Detritivores
- Organisms consuming non-living material, such as many fungi, bacteria,
and earthworms.
- Dioecious
- Having staminate and pistillate flowers on different plants of the
same species.
- Diploid
- An individual having two chromosome sets in each of its cells.
- Dominant
- An allele that expresses its phenotypic effect even when heterozygous
with a recessive allele.
- Donor Control
- A predator-prey interaction in which the predator does not control
the prey population size.
E
- Ecosystem
- The organisms of a particular habitat, such as a pond or forest, together
with the physical environment inwhich they live; a dynamic complex of
plant, animal, fungal, and microorganism communities and their associated
non-living environment interacting as an ecological unit. Ecosystems
have no fixed boundaries; instead, their parameters are set according
to the scientific, management, or policy question being examined. Depending
upon the purpose of analysis, a single lake, a watershed, or an entire
region could be an ecosystem.
- Ecotype
- A genetically differentiated subpopulation that is restricted to a
specific habitat.
- Egg
- A nonmotile female gamete.
- Elongation Region
- Existing root cells enlarge in size which moves the roots through
the soil.
- Embryo
- The rudimentary plant in a seed. The embryo arises from the zygote.
- Embryonic Stem
- This structure is composed of two parts. The epicotyl is that portion
of the stem above the cotyledons and below the plumule. The hypocotyl
is stem tissue between the cotyledons and the radicle.
- Endemic
- Restricted to a specified region or locality.
- Endodermis
- Usually a single layer of root cells surrounding the stele.
- Endosperm
- Triploid tissue of monocots that arises from the triple fusion of
a sperm nuclei with the polar nuclei of the embryo sac. In seeds of
certain species, the endosperm persists as a storage tissue and is used
by the seedling during germination for growth. It is composed mostly
of starch cells
- Environmental Heterogeneity
- The physical or temporal patchiness of the environment. Heterogeneity
exists at all scales within natural communities, ranging from habitat
differences between the top and underside of a leaf, to habitat patches
created by treefalls within a forest, to the pattern of forests and
grasslands within a region.
- Epidermis
- Outermost layer of cells on roots, stems, and leaves which serves
a protective function.
- Epigeal Emergence
- A type of emergence common in dicots characterized by the elongation
of the hypogeal pulling the cotyledons to the ground surface
- Evolution
- Any gradual change. Organic evolution is any genetic change in organisms
from generation to generation.
- Ex situ Conservation
- A conservation method that entails the removal of germplasm resources
(seed, pollen, sperm, individual organisms, from their original habitat
or natural environment. Keeping components of biodiversity alive outside
of their original habitat or natural environment.
- Extinction
- The evolutionary termination of a species caused by the failure to
reproduce and the death of all remaining members of the species; the
natural failure to adapt to environmental change.
F
- Fauna
- All of the animals found in a given area.
- Fertilization (syngamy)
- Formation of a zygote through the fusion of two gametes.
- Fibrous Root System
- The primary root (radicle) is not dominant in relation to those of
its secondary and tertiary branches.
- Filament
- Structure that supports the anther so that it can disseminate pollen
to flowers on the same plant or flowers on other plants.
- Flora
- All of the plants found in a given area.
- Floret
- Monocot flower that consists of a lemma and palea, lodicules, stamens,
and the pistil.
- Frugivore
- An animal that eats fruit.
- Fruit
- A mature ovary usually containing seeds (one or many). The outside
covering consists of the ovary wall (pericarp) and any other flower
components such as the withered remains of the stamens, sepals, petals,
etc. that may still be attached
G
- Gametes
- A sex cell; one of two cells that unite, forming a zygote.
- Gametophyte
- The haploid (n) gamete-producing phase of the life cycle of an organism
that exhibits Alternation of Generations.
- Gene
- The functional unit of heredity; the part of the DNA molecule that
encodes a single enzyme or structural protein unit.
- Gene Bank
- A facility established for the ex situ conservation of individuals
(seeds), tissues, or reproductive cells of plants or animals.
- Gene Pool
- All of the alleles available among the reproductive members of a population from which gametes can be drawn.
- Genetic Diversity
- Variation in the genetic composition of individuals within or among
species; the heritable genetic variation within and among populations.
- Genetic Erosion
- An irreversible loss in genetic diversity, usually of crop plants or
domestic animals.
- Genetic Vulnerability
- Potential for rapid, large-scale disease or insect epidemics, usually due
to genetic uniformity of domesticated crops or animals.
- Genome
- The entire complement of genetic material in a chromosome set.
- Genotype
- The set of genes possessed by an individual organism.
- Germination
- A time beginning with water uptake by the seed (imbibition) continuing
as the radicle breaks through the seed coat before the shoot does, ending
with the start of elongation by the embryonic axis, usually the radicle.
The first step in germination is the absorption of water and oxygen
by the seed. During and following this water absorption stage, enzymes
are formed which convert starch, fats, and protein into smaller more
soluble forms which can be transported to sites of growth. A seed is
germinated when the radicle and shoot have elongated and broken through
the seed coat.
- Germplasm
- The genetic material, especially its specific molecular and chemical
constitution, that comprises the physical basis of the inherited qualities
of an organism. In plant breeding, the terms often refers
to the genetic base of
a particular crop, including individuals, populations, or relatives that
may contribute genetically to its improvement.
- Glumes
- Two hardened or thin and chaffy bracts at the base of a spikelet.
- Growing Point
- The plant part where differentiation of leaves, tillers, and the
inflorescence occurs.
- Guard Cells
- Control the opening and closing of the stomata.
- Guild
- A group of organisms that share a common food resource.
H
- Habitat
- The environment in which an organism lives. Habitat can also refer
to the organisms and physical environment in a particular place.
- Heritability
- The proportion of total phenotypic variance at the population level
that is contributed by genetic variance (also called heritability in
the broad sense). Heritability in the narrow sense: The proportion of
phenotypic variance that can be attributed to additive genetic variance.
- Heterozygote
- An individual having unlike alleles at one or more corresponding loci.
- Hilum
- A detachment scar found on the dicot seed surface
- Homeologous Chromosomes
- Partially homologous chromosomes, usually indicating that they were derived
from a common ancestry.
- Homologous Chromosomes
- Pairs of chromosomes that associate together in prophase I of meiosis;
each member of a pair is derived from a different parent.
- Homozygote
- An individual aving like alleles at corresponding loci on homologous
chromosomes.
- Hybridization
- Crossing of individuals from genetically different strains, populations,
or species.
- Hypogeal Emergence
- A type of emergence common in monocots characterized by the elongation
of the epicotyl and the cotyledons remaining below ground
I
- Imperfect Flower
- A flower that is missing either the pistil or stamens, the essential
components.
- Inbreeding
- A mating system involving the mating or breeding of closely related
individuals, the most extreme form of which is self-fertilization. It
is used to "fix" economically useful genetic traits in genetically improved
populations; however, it also can result in fixation of deleterious
recessive alleles.
- Inbreeding Depression
- A reduction in fitness or vigor as a result of fixation of deleterious,
recessive alleles from consistent inbreeding in a normally outbreeding
population.
- Indicator Species
- A species whose status provides information on the overall condition
of the ecosystem and of other species in that ecosystem.
- Indigenous Peoples
- People whose ancestors inhabited a place or country when persons from
another culture or ethnic background arrived on the scene and dominated
them through conquest, settlement, or other means and who today live
more in conformity with their own social, economic, and cultural customs
and traditions than with those of the country of which they now form
a part (also: "native peoples" or "tribal peoples").
- Inflorescence
- A cluster of flowers.
- In situ Conservation
- A conservation method that attempts to preserve the genetic integrity
of gene resources by conserving them within the evolutionary dynamic
ecosystems of the original habitat or natural environment.
- Intellectual Property Right
- A right enabling an inventor to exclude imitators from the market
for a limited time.
- Internode
- Areas between stem nodes which contain elongated cells.
- Introduced Species
- A species occurring in an area outside of its historically known natural
range as a result of intentional or accidental dispersal by human activities.
Also known as alien species.
- In vitro
- Storage of plant or animal germplasm in tissue-culture form in glass
containers.
J
K
- Keystone Species
- A species whose loss from an ecosystem would cause a greater than
average change in other species populations or ecosystem processes.
L
- Landraces
- A crop cultivar or animal breed that evolved with and has been genetically
improved by traditional agriculturalists, but has not been influenced
by modern breeding practices. Often referred to as "local varieties".
May be heterogeneous mixtures.
- Leaf Axil
- The junction of the leaf with the main stem.
- Leaf Blades
- One of the two components of a monocot leaf that is responsible for
most of the photosynthesis that occurs in plants.
- Lemma and Palea
- Two protective bracts at the base of each floret.
- Life Form
- Characteristic structure of a plant or animal.
- Ligule
- A thin membrane arising from the upper side of the leaf blade at
the junction of the blade with the sheath which is important in the
identification of grasses.
- Locus
- A specific place on a chromosome where a gene is located.
- Lodicules
- Structure found at the base of the pistil in the floret that will
enlarge in size, forcing open the lemma and palea so that cross pollination
can occur, after absorbing water.
M
- Maturation Region
- Root cells differentiate into specialized tissues such as the xylem,
phloem, cortex, root hairs, etc..
- Meiosis
- The process of two successive nuclear divisions through which segregation
of genes occurs and a single diploid (2n) cell becomes four haploid
(n) cells.
- Meristem Region
- A part of the root where cells are actively dividing by a process
called mitosis.
- Micropyle
- A small seed surface opening usually found in dicot seeds where the
pollen tube entered the ovule
- Minimum Viable Population
- The smallest isolated population having a good chance of surviving
for a given number of years despite the foreseeable effects of demographic,
environmental, and genetic events and natural catastrophes. (The probability
of persistence and the time of persistence are often taken to be 99
percent and 1000 years, respectively.)
- Mitosis
- The process of nuclear division (karyokinesis) in cells that produces
daughter cells that are genetically identical to each other and to the
parent cell.
- Monocropping
- Production of a single crop species in a field.
- Monoculture
- Same as Monocropping.
- Monoecious
- A plant that has separate pistillate and staminate flowers such as
maize.
- Mutualism
- Relationship between two or more species that benefits all parties.
- Mycorrhizal Fungi
- A fungus living in a mutualistic association with plants and facilitating
nutrient and water uptake.
N
- National Income Accounts
- System of record by which the vigor of a nation's economy is measured.
(Results are often listed as Gross National Product, or Gross Domestic
Product.)
- Native Species
- Plants, animals, fungi, and microorganisms that occur naturally in
a given area or region.
- Nitrogen Fixation
- A process whereby nitrogen fixing bacteria living in mutualistic associations
with plants convert atmospheric nitrogen to nitrogen compounds that
plants can utilize directly.
- Nectarivore
- An animal that eats nectar.
- Node
- Areas of compressed stem tissue which give rise to other specialized
plant parts such as leaves, branches, and flowers.
- Non-governmental Organization (NGO)
- A non-profit group or association organized outside of institutionalized
political structures to realize particular social objectives (such as
environmental protection) or serve particular constituencies (such as
indigenous peoples). NGO activities range from research, information
distribution, training, local organization, and community service to
legal advocacy, lobbying for legislative change, and civil disobedience.
NGOs range in size from small groups within a particular community to
huge membership groups with a national or international scope.
O
- Orthodox Seed
- Seed that can be dried to moisture levels between 4 and 6 percent
and kept at low temperatures.
- Ovary
- Female reproductive structure that contains eggs within one or more
ovules.
P
- Palisade Parenchyma
- Internal leaf cells that contain the majority of the chloroplasts.
- Parataxonomists
- Field-trained biodiversity collection and inventory specialists recruited
from local areas.
- Patent
- A government grant of temporary monopoly rights on innovative processes
or products.
- Pathogen
- A disease-causing microorganism; a bacterium, fungus or virus.
- Pedicel
- Stem tissue that supports the flowers.
- Peduncle
- Specialized stem tissue for the support of a flower or an inflorescence.
The last elongated internode which supports the inflorescence.
- Perfect Flower
- A flower that contains both the pistil and the stamens, the essential
components.
- Pericycle
- Root tissue immediately inside the endodermis and outside the vascular
tissue that consists of parenchyma cells and is the site of lateral
root formation.
- Petal
- A flower structure that can protect the surrounding reproductive
components or can attract insect pollinators.
- Petiole
- Modified stem tissue that supports a simple or compound leaf and
contains the vascular bundles.
- Phenotype
- The morphological, physiological, biochemical, behavioral, and other
properties of an organism that develop through the interaction of genes
and environment. (See genotype.)
- Phylogenetic
- Pertaining to the evolutionary history of a particular group of organisms.
- Phylum
- In taxonomy, a high-level category just beneath the kingdom and above
the class; a group of related, similar classes.
- Pistil
- Female reproductive structure that consists of the stigma, style,
and ovary. It is sometimes called the gynoecium.
- Pith
- Central tissue of stems and roots.
- Plant Variety Protection
- In the US, the Plant Variety Protection Act provides patent-like protection
for sexually (i.e., seed) reproduced plants, other than fungi or bacteria,
and to
crops reproduced by tubers. The variety must be distinct from all other
varieties, uniform, and stable.
- Pleiotropy
- The effect of a single gene on more than one trait.
- Plumule
- The embryonic shoot
- Pollination
- Fertilization of the embryo by pollen.
- Polyploid
- An individual that carries more than two complete sets of homologous
chromosomes.
- Population
- A group of individuals with common ancestry that are much more likely
to mate with one another than with individuals from another such group.
- Predator Control
- A predator-prey interaction in which the predator controls the prey
population size; that is, in which the predator population is the limiting
factor for the prey population size.
- Primary [or natural] forest
- A forest largely undisturbed by human activities.
- Primary Productivity
- The transformation of chemical or solar energy to biomass. Most primary
production occurs through photosynthesis, whereby green plants convert
solar energy, carbon dioxide, and water to glucose and eventually to
plant tissue. In addition, some bacteria in the deep sea can convert
chemical energy to biomass through chemosynthesis. Primary production
refers to the amount of material produced. Net primary production is
the measure of the actual accumulation of biomass after some of the
products of photosynthesis (or chemosynthesis) are expended for the
plant's own maintenance. Productivity, or the rate of production, is
affected by various environmental factors, including the amount of solar
radiation, the availability of water and mineral nutrients, and temperature.
- Primary Tiller
- A tiller produced by a node on the main stem.
- Protected Area
- A legally established land or water area under either public or private
ownership that is regulated and managed to achieve specific conservation
objectives.
Q
R
- Rachilla
- The supporting stem-like structure of the spikelet.
- Rachis
- The central axis of a raceme or spike.
- Radicle
- The embryonic root; the first structure to emerge during seed germination
- Raphe
- A seed surface ridge found in some dicots
- Recalcitrant Seed
- Seed that does not survive drying and freezing.
- Recepticle
- Enlarged portion of the pedicel at the base of the flower.
- Recessive
- The member of an allelic pair that is not expressed when the other,
dominant allele is present on the homologous chromosome.
- Rehabilitation
- The recovery of specific ecosystem services in a degraded ecosystem
or habitat.
- Restoration
- The return of an ecosystem or habitat to its original community structure,
natural complement of species, and natural functions.
- Rhizome
- A horizontal, underground stem.
- Root Cap
- Dead plant cells at the end of the root which serve protective and
lubricative functions.
- Root Hairs
- Short-lived extensions of root epidermal cells that increase the
absorptive capacity of the root system by 20 to 30%.
S
- Scutellum
- The modified cotyledon structure found in monocot seeds that absorbs
food reserves from the endosperm and transports it to the embryo.
- Secondary Tiller
- A tiller produced by a primary tiller.
- Seed
- A mature ovule with its normal coverings. A seed consists of the seed
coat, embryo, and in certain plants, an endosperm.
- Seedbank
- A facility designed for the ex situ conservation of individual plant
varieties through seed preservation and storage.
- Selection
- Natural selection is the differential contribution of offspring to
the next generation by various genetic types belonging to the same populations.
Artificial selection is the intentional manipulation by man of the fitness
of individuals in a population to produce a desired evolutionary response.
- Seminal Roots
- The roots originating from the seed.
- Sepal
- Small flower structure below the outermost whorl of petals.
- Sexual Reproduction
- Reproduction involving the union of gametes.
- Sheath
- One of the two parts of a monocot leaf consisting of tissue arising
from each node that is folded around the stem.
- Species
- A group of organisms capable of interbreeding freely with each other
but not with members of other species.
- Species Diversity
- A function of the distribution and abundance of species. Approximately
synonymous with Species Richness. In more technical literature, includes
considerations of the evenness of species abundances. An ecosystem is
said to be more diverse, according to the more technical definition,
if species present have equal population sizes and less diverse if many
species are rare and some are very common.
- Species Richness
- The number of species within a region. A term commonly used as a measure
of Species Diversity, but technically only one aspect of diversity.
- Sperm
- A male gamete; it is usually motile and smaller than the corresponding
female gamete.
- Spikelet
- A monocot inflorescence component that consists of two glumes, one
or more florets, and the rachilla.
- Spongy Mesophyll Parenchyma
- Internal leaf cells that are frequently lobed and are separated by
intercellular spaces stages of development.
- Spores
- A reproductive cell or aggregation of cells capable of developing
directly into a gametophyte or other body without uniting with another
cell;sexual spores formed as a result of meiosis occurring are often
called meiospores; spores produced by mitosis may be referred to as
vegetative spores.
- Spore Mother Cells
- A diploid cell that becomes four haploid spores or nuclei as a result
of undergoing meiosis.
- Sporophyte
- The diploid (2n) spore-producing phase of the life cycle of an organism
exhibiting Alternation of Generations.
- Stability
- A function of several characteristics of community or ecosystem dynamics,
including the degree of population fluctuations, the community's resistance
to disturbances, the speed of recovery from disturbances, and the persistence
of the community's composition through time. Also refers to a cultivar's
capacity to maintain high yield potential across a range of environments.
- Stamens
- Male reproductive structures of a flower composed of filaments and
anthers. It is also referred to in the literature as the androecium.
- Standard Wings & Keel
- The specialized petals of the five-part corolla found in the Fabaceae
(Leguminosae) family.
- Stele
- Root tissue composed of the xylem, phloem, and pericycle.
- Stigma
- Female reproductive structure that receives/collects pollen.
- Stipules
- A pair of bracts at the base of the petiole that protects the axillary
bud.
- Stolon
- A horizontal stem (runner) that grows along the ground surface;
it may form adventitious roots and plantlets.
- Stomata
- Pores in the leaf epidermis that allow carbon dioxide to enter and
water vapor to leave.
- Style
- Female reproductive structure that connects the stigma to the ovary;
the pollen tube must pass through this tissue to reach the eggs in the
ovary.
- Subspecies
- A subdivision of a species; a population or series of populations
occupying a discrete range and differing genetically from other subspecies
of the same species.
- Succession
- The more or less predictable changes in the composition of communities
following a natural or human disturbance. For example, after a gap is
made in a forest by logging, clearing, fire, or treefall, the initial
(or "pioneer") species are often fast-growing and shade-intolerant.
These species are eventually replaced by shade-tolerant species that
can grown beneath the pioneers. If a community is not further disturbed,
the outcome of the successional sequence may be a so-called climax community
whose composition is unchanging. In practice, many communities are frequently
disturbed and may never reach a climax composition.
- Sustainable development
- Development that meets the needs and aspirations of the current generation
without compromising the ability to meet those of future generations.
- Systematics
- The study of the historical evolutionary and genetic relationships
among organisms and of their phenotypic similarities and differences.
T
- Tap Root System
- The primary root (radicle) is dominant in relation to those of its
secondary and tertiary branches.
- Taxon (pl. taxa)
- The named classification unit (e.g. Homo sapiens, Hominidae, or Mammalia)
to which individuals, or sets of species, are assigned. Higher taxa
are those above the species level.
- Taxonomy
- The naming and assignment of organisms to taxa.
- Tertiary Tiller
- A tiller produced by a secondary tiller.
- Tiller
- A shoot that arises from buds at the base of a plant.
- Transformation
- The directed modification of a genome by the external application
of DNA from a cell of a different genotype.
- Trophic Level
- Position in the food chain, determined by the number of energy-transfer
steps to that level.
- Tuber
- An enlarged underground stem tip having numerous buds or eyes and used
for food storage.
U
- Utility Patent
- Provides patent protection for plant varieties, traits, parts, and processes.
V
- Variety
- Often used as a synonym for Cultivar. A variety in the botanical
sense is a subtaxon to a species.
- Vascular Plants
- Plants with a well-developed vascular system that transports water,
minerals, sugars, and other nutrients throughout the plant body. Excludes
the bryophytes: mosses, hornworts, and liverworts.
- Venation
- The arrangement of leaf veins which may be parallel, the main veins
run side by side from the base to the apex without branching or intersection,
or net, with veins arranged in all directions with branching and intersecting.
W
X
Y
Z
- Zygote
- The product of the union of two gametes.
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