Horticulture & Soils Terms Flashcards
Xylem
Vascular tissue that carries water and minerals upward in plants. It is closer to the top of a leaf than the Phloem.
2 types in woody plants:
- Sapwood is active xylem
- Heartwood is inactive Xylem
Phloem
Vascular tissue that moves sugars through plants. It’s closer to the bottom of a leaf than Xylem. This is why aphids like leaf undersides.
Vascular cambium
Merestematic tissue that can become Xylem or Phloem cells. It sits between the two.
Meristem tissue
Tissue that can develop into other tissues. Includes Apical (shoot & root tips, buds) and Lateral (cambium)
Apical Meristem
Meristematic tissue found in shoot tips, root tips, axillary buds. It enables the plant to develop new tissue and grow taller (vs wider).
Lateral Meristem
Meristematic tissue that helps plants develop greater width ( vs height). Includes vascular cambium and cork cambium.
Crown
The transition zone between the roots and the shoot.
Palisade cells
Long cells just below the upper epidermis that contain most of the chloroplasts.
Stomata
An opening on the underside of a leaf that is involved in transpiration. Stomata are surrounded by guard cells which facilitate opening & closing.
Monocotyledon / Monocot
(list key characteristics)
A class of flowering plants (grasses, Lilies, orchids, palms)
- One seed leaf (cotyledon)
- Parallel venation
- Flower and sepal petals come in 3s
- Vascular tissue is scattered thru stem (typically no cambia)
- fibrous roots (no tap root)
- Herbaceous
Dicotyledon / Dicot
(List key traits)
A class of flowering plants
- 2 seed leaves ( cotyledons)
- Branched venation ( palmate or pinnate)
- Flower & sepal petals in 4s or 5s
- Vascular tissue is in a circular pattern or in a ring
- have tap roots
- not herbaceous
Variety
A species sub-classification that is naturally occurring in the wild (vs cultivated)
Cultivar
A human developed variety (cultivated variety)
Clone
One of a group of genetically identical plants that originate from a single individual and are reproduced by vegetative means (cuttings, grafts).
A cloned is a specific type of cultivar.
Hybrid
The progeny of a cross between individuals that differ by one or more specific genes.
Spermatophyte
A Division of Seed bearing plants. Includes both:
Gymnosperms - plants whose seeds are exposed at the base of scales (cones) and don’t flower
Angiosperms - flowering plants whose seeds are enclosed in a dry or fleshy fruit that develops from the ovary.
Annuals
Plants that complete their full lifecycle (seed, flowering, reseeding) in one year or season.
Biennials
Plants that complete their lifecycle over 2 years or growing seasons. Reproduction takes place in the second year.
Perennials
Plants that continue growing for multiple years. Reproduction doesn’t start until the plant reaches maturity.
Photosynthesis
The conversion of CO2 & H2O to glucose and O2 in the presence of light and chlorophyll.
Transformation of light energy into stored chemical energy.
Only occurs in tissues with chlorophyll.
Respiration
Controlled breakdown of carbohydrates for use as energy.
Essentially the reverse of photosynthesis
Occurs in all living tissues, even dormant and post harvest tissues.
Transpiration
Evaporative loss of H2O vapor via the stomata.
Translocation
The movement of H2O, minerals, food etc from one part of the plant to another.
Mainly takes place in Xylem and Phloem.
Plant Hormones / Phytohormones
(list them)
Auxins- cell enlargement, shoot growth, suppress lateral bud development
Gibberellins- cell division, stem elongation, flowering
Cytokinins- cell division
Ethylene- accelerates ripening, senescence
Abscisic acid- regulates dormancy in shoots/seeds, stomata closing
Apical dominance
A phenomenon in plants where a top shoot (apical) dominates and inhibits the outgrowth of other (lateral) shoots.
Vegetative growth stages
Development of root, stem, or leaf tissues
- Seed germination - beginning of growth & development. Starts when a seed takes in H2O and ends when the seedling is self sustaining
- Juvenility- from seedling stage to maturity. Vigorous growth stage.
- Maturity- when the plant is fully developed & capable of initiating flowers. Bulbs, tubers, fleshy roots & runners also can develop at this stage.
Reproductive development stages (list)
Development of flower, fruit, and seed tissues.
Flower induction- begins when meristems (buds, shoots) are induced to produce reproductive organs (flowers). Ends with fruit formation or senescence.
Flower & fruit development- pollination, fertilization, fruit set
Fruit ripening- sugars & aromatic compounds accumulate to contribute to flavor.
Vernalization
The induction of the flowering process by exposure to long periods of cold.
Hardening
Toughening plants for transplant by gradual sun exposure and withholding H2O, nitrogen fertilizer
Petiole
The stalk that joins a leaf blade to a stem.
Supports leaves turning to collect the sun.
Not all leaves have petioles.
Lamina
The leaf blade in a monocot (grass), which sits above the collar (meristematic tissue) and sheath (stem).
Collar
A band of meristematic tissue in monocots that sits above the Sheath (stem) and below the Lamina (blade).
Sheath
The name for the stem in monocots (grasses). It sits below the Collar and Lamina ( leaf blade).
Perfect Flowers
Have both male and female parts. Most plants have perfect flowers.
Male parts- STAMEN: anther; filament
Female parts- PISTIL: stigma, style, ovary
Imperfect Flowers
Have either male or female parts, not both.
Male only- Staminate
Female only- Pistilate
Monoecious- male and female flowers are separate but on the same plant
Dioecious- male and female flowers are on different plants.
Composite flowers
Have a head of flowers that looks like a single flower but is comprised of many smaller flowers (florets). The Daisy family is a good example.
Ray flowers (male)
Disk flowers (female)
Abiotic
Physical rather than biological.
Plant Taxonomy. (List)
Division Domain
Subdivision. Kingdom
Class. Phylum
Order. Order
Family. Family
Genus. Genus
Species. Species
Sink
Structures within a plant that receive food priority; includes meristems and fruits
Fruit
Plant part that contains a mature, swollen ovary and the seed
Seeds
Contain embryonic plant tissue in a dormant state with food reserves to sustain it through germination
Sepal
Small leaflike structures at the base of flowers. Sits above the receptacle. (Examples- cap on a tomato or a strawberry)
Receptacle
Sits below the sepal. This is where the floral structures are attached to the plant
Buds
Meristematic structures along the stem comprised of compressed, immature leafy shoots, flowers or both.
Internode
The interval on the stem between the nodes
Floral induction
The process in which the apical meristem (growing tip) of a flowering plant switches from vegetative growth to reproductive growth and becomes competent to develop flowers.
Pollination
The transfer of pollen to the female style, ovary , or flower to enable fertilization
Stamen
The male reproductive parts of a flower, comprising the anther and the filament
Pistil
The female parts of a flower, comprising the stigma, style, and ovary
Monoecious
Angiosperms in which the male and female flowers are on the same plant.
Dioecious
Angiosperms in which the male and female flowers are on separate plants.
Turgor pressure
Pressure exerted by fluids in a cell that pushes the cell membrane against the cell wall, giving rigidity to the plant tissue.
Pectin
A polysaccharide that serves as a cementing agent between cells
Adventitious roots
Arise from some part of the plant other than roots.
Compound leaf
Has multiple petioles and blade segments that are called leaflets.
Stratification
Species that need exposure to cold temps (< 45) to germinate
Radicle
First thing to emerge from a germinating seed- a tiny bit of root
Hypocotyl
Structure that emerges from a germinating seed and becomes the stem
Cotyledons
First leaves to emerge from a germinating seed. They don’t photosynthesize though, just give stored energy to feed the growing plant until the true leaves come out.
Tilth
A measure of Soil fitness as medium for growing plants
Soil Texture
The relative proportions of Sand, Silt, and clay mineral particles
Adsorption (in soils)
The attraction of ions or molecules to the surface of a solid (such as soil).
Ex. Clay soil carries a net negative charge and attracts positively charged ions (Mg, Ca, K, NH4 etc. )
Absorption
Active or passive movement into something. Example- movement of ions or water into roots
Cation Exchange Capacity. (CEC)
Measures the amount of cations that can be adsorbed or held by a soil.
It’s important because when cations are released from the soil they can be available for absorption by roots. Higher capacity= more fertile soil.
Bulk Density (in soils)
A measure of the air or pore space in a soil (it does not measure pore size though)
Soil Structure
The way in which groups of soil particles (aggregates or peds) are arranged.
Clorpt Equation
A measure of factors influencing soil formation:
CLimate
Organisms
Relief
Parent material
Time
Soil Saprophytes
Beneficial micro organisms ( bacteria & fungi). That decompose organic material into humus and available nutrients.
Microrrhizae
Associations between plant roots and soil fungi. >75% of plants form these associations. Most are beneficial to both organisms.
Soil Moisture Tension (SMT)
The strength of soil water adhesion
Field Capacity (FC)
The max amount of water a soil can hold against the downward force of gravity after a soil has been saturated.
Permanent Wilting Capacity (PWC)
The amount of water remaining in the soil when the water in the soil is held too tightly for plants to absorb it and plants wilt permanently
Plant-available Water
The soil water held between FC (field capacity) and PWP (permanent wilt percentage
Leaching
The loss of water , dissolved nutrients, and salts that move down into the soil profile beyond the root zone.
Infiltration
When water moves into the soil and doesn’t run off.
Percolation
Movement of water THROUGH the soil, deeper into the soil horizon.
it is often accompanied by leaching.
Mineral Particles
Sand, silt, clay
Organic Matter
Carbon-based compounds; living organisms in the soil, roots, anything that was once alive and in the process of or already has decomposed.
Agregates
Sand, silt, clay, and organic matter bound together into water-stable aggregates.
They can look like peas or cottage cheese in the soil.
Physical Soil Structure
How the parent rock breaks apart, related to how water is able to move through the soil.
Biological Soil Structure.
The arrangement of aggregates built by the microbial community so there is space for H2O & gas to move into and be held in pore spaces and move deeper into The soil.
Pores
Space where H2O & gas can be held in soil.
Nutrient
Substance that provides nourishment, promotes growth, or provides energy to sustain life.
pH
The potential of hydrogen. The acidity or alkalinity of a solution.
The relative concentration of H+ and OH- ions in soil.
Soil Solution
Free flowing water in the soil that occupies soil pore spaces and contains nutrients, microbes etc.
Ion
An atom or molecule with a positive or negative charge
Cation
An ion with a net positive electrical charge
Anion
An ion with a net negative electrical charge
Soil Food Web
All living organisms and how they interact in the soil
Microbes
Organisms so small they require a microscope to be seen.
Main soil microbes:
Bacteria
Fungi
Protozoa
Nematodes
Microarthropods
Nutrient Cycling
(in the soil food web)
The way nutrients change form as they go through different organisms
Rhizosphere
The area immediately around plant roots comprising roots and symbiotic mycorrhizal fungi.
Exudates
The substances that come out of roots , many of which are the result of photosynthesis.
Saprotrophic Organisms
Organisms that decompose organic matter and can extract minerals from parent rock.
Also known as decomposers.
Symbiosis
Organisms that associate with other organisms, typically in a mutually beneficial way.
Pedogenesis
How soil forms
Soil Profile
The combination of layers or soil ‘horizons’ of a given soil. Most soils have 3 major horizons (A,B,C).
O- humus or organic
A- topsoil
E- eluviated
B- subsoil
C- parent soil
R- bedrock (not part of the soil)
Soil Degradation
Process that impairs the capacity of soil to function. Can be caused by humans or nature.
Examples: Salinization, contamination, desertification, erosion.
Rhizophagy
A cyclical nutrient uptake mechanism in which plant roots engulf microbes, extract nutrients and then expel them into the rhizosphere to repeat the cycle.
Mulch
Material put on top of soil.
Can be carbon based (wood chips, bark, straw) which hold moisture in.
Can be mineral based like pebbles, rock dust, or sand.
Compost
Organic matter that has been broken down, usually under aerobic conditions, so that the original material is no longer recognizable.
Can be completely plant based or contain animal manure.
Amendment
A substance added to soil to alter one or more of its physical, chemical or biological properties.
Examples; compost, worm castings, manure, wood fines, coir, lime, gypsum.
Fertilizer
Commonly used to mean an organic or synthetic substance added to soil to provide plants with essential nutrients.
Labeled with NPK ratio (by weight)
Organic fertilizer
Fertilizers that contain carbon. Microbes may be required to make the fertilizer available to plants.
Synthetic Fertilizer
Chemically manufactured materials containing one or more essential nutrients. The nutrients are in a form the plant can directly take up.
IPM
(Integrated Pest Management)
An ecosystem based strategy that focuses on long term prevention of pests and disease/damage.
Uses biological, cultural, mechanical/physical, and chemical controls in a way that minimizes risks to the health of humans, beneficial organisms, and the environment.
Biocide
A chemical compound or biological product used to kill, control growth, or repel a specific organism.
Includes; herbicides, fungicides, insecticides, pesticides.
Raised Bed
A structure that sits on top of the soil rather than an impermeable surface. Water and roots can move into the soil below.
Container
A vessel either with a bottom or that sits on a solid surface like concrete or asphalt.
Hydrophobic Soil
Soil that does not absorb water.
Soil Compaction
Has reduced pore space making it difficult for water and air to penetrate
Is difficult to irrigate and may erode due to water runoff.
Minerals in Soil
Sand, silt, clay and larger materials; lava rock, pebbles, vermiculite, perlite.
Will not break down significantly over time. Can become compacted if not cared for.
Organic matter in soil
Consists of plant or animal tissue in various stages of decomposition (compost, woody amendment, coir, organic fertilizers).
Serves as food for microbes, which may cause the soil level to drop.
Mineral Amendments
Inorganic soil additives examples; greensand (K and Fe), gypsum (Sulfer and Ca), and lime (Ca). Some impact soil pH.
Carbon Sequestration
The process of capturing and storing carbon dioxide. Goal is to stabilize Carbon in solid and dissolved forms to minimize impact on global warming.
Albedo
Describes the reflectivity of a surface.
Urban Heat Island
Urbanized areas that experience higher temps than outlying areas.
Roads, buildings, and other infrastructure absorb and re-emit the suns heat more so than natural landscapes.
