Plant Science Terms - F

Fallow - a system in which land is left unplanted without a crop for one or more growing seasons to accumulate moisture and restore nutrients

Family - a sub-order in the classification of plants

Fasciation - distortion of a plant that results in thin, flattened, and sometimes curved shoots

Fastigiate - (of a tree or shrub) having the branches sloping upward more or less parallel to the main stem 

Feeder roots - fine roots and root branches with a large absorbing area (root hairs.) Responsible for taking up the majority of a plant’s water and nutrients from the soil

Fertility (soil) - presence of minerals necessary for plant life

Fertilization - fusion of male and female germ cells following pollination; the addition of plant nutrients to the environment around a plant

Fertilizer - any substance added to the soil (or sprayed on plants) to supply those elements required in plant nutrition

Fertilizing - to add nutrition to your plants using either commercial or non commercial fertilizers or compost

Fertilizer analysis - minimum amount of nitrogen, phosphorus (as P2O5), and potassium (as K2O) in a fertilizer expressed as a percentage of total fertilizer weight as stated on the label. Nitrogen (N) is always listed first, phosphorus (P) second, and potassium (K) third. An example would be as 16-4-8

Fertilizer ratio - the smallest whole number relationship in relative proportion of N, P2O5, and K2O. The ratios of 16-4-8 and 8-2-4 are both 4:1:2, which means 4 parts nitrogen to 1 part phosphorus to 2 parts potassium

Fibrous root - a root system that branches in all directions, often directly from the plant’s crown, rather than branching in a hierarchical fashion from a central root. (See also Taproot.)

Field capacity - amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This usually takes place 2–3 days after rain or irrigation in pervious soils of uniform structure and texture

Field signature - distribution pattern of the disease over all plants of the same species

Filament - stalk supporting a flower’s anthers

Filler - plants that fill in the middle area of a container connecting the spillers and fillers and making the container look full

Flag or Flagging - loss of turgor and drooping of plant parts, usually as a result of water stress. Can be seen as branch loss in a tree

Flecking or stippling - numerous very small chlorotic or necrotic points

Floating row covers - covers, usually of a cloth-like material, placed over growing plants and used to protect the plants growing beneath from undesirable pests and climate

Floricane - second-year growth of cane berries. Produces fruit on laterals

Floriculture - study of growing, marketing, and arranging flowers and foliage plants

Flower - a shoot of determinate (limited in number) growth with modified leaves that is supported by a short stem; the structure involved in the reproductive processes of plants that bear enclosed seeds in their fruits

Flower bud - a type of bud that produces one or more flowers

Foliar fertilization/feeding - fertilization of a plant by applying diluted soluble fertilizer, such as fish emulsion or kelp, directly to the leaves

Foot-candle - a unit of measure of the intensity of light falling on a surface, equal to one lumen per square foot and originally defined with reference to a standardized candle burning at one foot from a given surface

Force - to bring a plant into early growth, generally by raising the temperature or transplanting it to a warmer situation. Tulips and paper whites are examples of plants that often are forced

Forcing - manipulation of environmental factors which makes it possible to produce a marketable pot plant or cut flower out of season

Form - a naturally occurring characteristic different from other plants in the same population; growth habit (shape) of a plant

Formal - a garden that is laid out in precise symmetrical patterns; a flower, such as some camellias, that consists of layers of regularly overlapping petals

Foundation seed - seed stock handled to most nearly maintain specific genetic identity and purity under supervised or approved production methods certified by the agency

Frass - excrement of insect larvae

Frond - specifically, the foliage of ferns, but often applied to any foliage that looks fernlike, such as palm leaves

Frost-Free Date - average date in spring when your area no longer experiences frost and the average date in fall for when your area experiences the first frost.  This date is important for knowing when to plant in spring. Knowing both spring and fall frost dates will help you determine the length of your growing season

Frost pocket - a depression in the ground into which cold air drains but from which it cannot escape, thus causing it to be an area very subject to freeze injury

Fruit - an expanded and ripened ovary with attached and subtending reproductive structures that develops after fertilization occurs

Fruit rot - decay of fruit. May be firm or soft

Fruiting body - any spore-producing structure of a fungus. Many are small and dark. Some grow on the surface of leaves or stems

Fruiting habit - location and manner in which fruit is borne on woody plants

Full Sun - 6 or more hours of direct sun a day 

Full Shade - less than 4 hours of direct sun a day

Fumigation - application of a toxic gas or other volatile substance to disinfect soil or a container, such as a grain bin

Fungicide - a compound toxic to fungi

Fungus (Fungi) - a plant organism that lacks chlorophyll, reproduces via spores, and usually has filamentous growth. Examples are molds, yeasts, and mushrooms


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