Floral Diagram - A composite diagram of a transverse section through a flower to show the position of the various parts, and their relation with other parts.

Floral Envelope - The calyx and corolla, or perianth.

Floral Formula - A summary of the characteristics of a flower. K=calyx, C=corolla, A=Androecium (stamens), G=gynoecium (carpels). The number following represents the number of parts means that the parts are fused, e.g. C(5) means 5 fused petals. indicates I whorl fused to another, e.g. C(S)A would mean a corolla of S fused parts to which are joined S free stamens. A line below the figure for the gynoecium, means that it is superior, e.g. G5,  beside it, that it is perigynous, e.g. G(5)-, and above it inferior, e.g. G(3).
Floral Leaf - (1) A bract or bracteole. (2) A petal or sepal.

Flore Pleno - Used for a double flower in which carpels have also become modified into petals e.g., in Ranunculus aconitifoloius 'flore pleno'.

Floret - A small flower e.g., disco or ray floret which makes up the capitulum inflorescence of family Compositae. In grasses,lemma, palea and the flower within them comprise a floret.

Floristics - Dealing with the study which is involving taxonomic identification and the listing of all the plant species present in a community and the list so prepared gives the floristic composition of the community.

Flower - Used for the reproductive stem of the angiosperms. Typically it is comosed of a calyx of sepals, a corolla of petals, (these two being the perianth), an androecium of stamens, and a gynoecium of carpels. Any of these parts may not be present in a particular flower. The floral axis is the receptacle.

Fluid-Mosaic Model - According to this model, the structure of plasma membrane is like a fluid in which both phospholipid and proteins constituting the membrane are capable of lateral movement within the membrane.

Flushing - Used for a process by which soluble substances in the lower layers of the soil come upwards and get deposited at or near the soil surface. It occurs, for example, in water medows, fenlands and in area having springs.

FMN (flavin mononucleotide). A riboflavin-derived coenzyme similar to FAD. It acts as a prosthetic goup to several dehydrogenase. NADH dehydrogenase is an example of FMN con­taining enzyme.

Folic Acid - Used for a member of B group of vitamins which were first isolated from spinach leaves. Its activated form (tetra hydro folic acid), acts as a coenzyme in reactions which are involving transfer of hydroxymethyl, formyl and methyl groups.

Foliose - Used for organisms which are having leaf-like shape. This term is generally used to describe leaf-like plant body of lower plants e.g., certain lichens and liverworts.

Follice - (1) A many-seeded dry fruit which is derived from a single carpel, and splitted longitudinally down one side at dehiscence. (2) A small bladder present on the leaves of some mosses.

Food Body - A mass of cells present on the outside of a seedcoat, attracting ants which help in dispersal. The attraction is due to stored food, usually oils.

Food Chain - Describing the linear sequence of organisms which represent their prey-predator relationships in the ecosystem. Chain usually starts from a producer (autotrophic chain) and rarely has more than five steps in the series. Each organism at each step of chain is corresponding to one trophic level. Example of food chain is as follows: Festuca ovina (grass) ← Microtus agrestis (vole)  ← Mustela (weasel).
or Chaetoceros ← Calamus ← Ammodytes ← Clupea ← PhaIacrocorax ←  Navicula ←  Temora 

Food Web - Used for a network which is representing all the feeding relationships of organisms in an ecosystem. It com­prises of branched an inter-linked food chains.

Foot - Describing the basal portion of an embryo, sporophyte or spore producing body which is embedded in the parental tissue. It serves to anchor and absorbs nutrition from the parent.

Foot Rot - A plantdisease which is characterized by rotting of root system and lower portion of the stem. Example is foot rot of tomato which is caused by Phytohpthora cryptagea.
Forest - A major type of biotic community which is characterized           by dominance of  trees. Three major types of forests have been
recognized on the basis of climatic regions; cold forests tempera tee forests and tropical forests.
Form Genus, Form Species - A group of species having similar morphologica characters, but are not known certainly to be related by descent. The species form species.
Formic Dehydrogenase - An enzyme breaking down formic acid to carbon dioxide and water in the presence of co-enzyme I.
Formic Hydrogenlyase - An enzyme in a few groups of bacteria catalysing the combination of carbon dioxide and hydrogen, or bicarbonate ions and hydrogen to form formates.
            CO2­+ H2­ →  H+ + HC02­-
            HC03 -+H2­  →   HCOO - +H2­O

Fossils - A term used for the remains of organisms from past geo­logical ages which were preserved mostly in sedementary rocks as actual structures or as impressions, casts or moulds of structures which are no more living. Processes of fossil formation are carbonization, petrification etc. Remains of macroscopic parts e.g., branches, petioles, leaves, fruits and seeds are known as megafossils and those of microscopic structures e.g., pollens and spores are known as microfossils.

Founder Principle - According to this, a small pioneer com­mununity established in genetic isolation from the parent population will possess a small and possibly non-random selection of geness from the parental gene pool. Consequently, the community that is developing may take a different evolu­tionary course from that of the parent community.

Fraction I Protein - Used for soluble stroma protein of chloro­
plasts which accounts for 'SO per cent of the soluble stroma protein content. It consists of enzyme ribulose biphosphate carboxylase (RuBP). Its particles are almost isodiametric, between 10-12 nm in diameter and each is made up of twenty to thirty identical, smaller particles which are arranged in a cubic or octahedral 3-dimensionaJ array.