A varient of a species.

a subdivision of a species below the rank of variety (Bot. Code, Art. 4). In this sense forms are distinguished on morphological grounds. `A subdivision of a species of a parasitic or symbiotic microorganism distinguished primarily by adaptation to a particular host`; forma specialis (Bact. Code, Rec. 8a (5)).

A subdivision of species which occurs occasionally in the wild, seldom breeds true, and does not develop a natural population or distribution.

A subdivision within a species or variety.

In its strict philosophical usage, form is limited to its signification of the intrinsic principle of existence in any determinate essence. All species or nature, whether in itself material or existent as immaterial, is called a form. It is not unusual to speak of the angelic form, or even of the form of God, as signifying the nature, or essence, of the angel or of God.

species or subspecies; distinct, identifiable population

Any significant distinguishing taxonomical difference in appearance or shape from the type classification, though not resulting in new species or subspecies recognition.

A category below the species level; interpretation varies on the basis of date of use (see Appendix A).

pl. formae A minor variation within a species that is sufficiently distinctive to warrant recognition as a separate taxon. In cultivated plants, it is current practice to name these forms as cultivars.

A distinctive variant within a species which occurs at a frequency greater than 0.01%, and so is characterized by genetic continuity from generation to generation, and is maintained in the species by some selective advantage. Form is here used synonymously with "morph."

In botanical nomenclature, a form (forma) is a taxon at a rank below that of variety; it is an infraspecific taxon. Its name consists of three parts: a genus name, a specific epithet, and an infraspecific epithet. The abbreviation "f." or the full "forma" should be put before the infraspecific epithet to indicate the rank.