FACULTATIVE: Not restricted to a particular way of life.
FALCATE: Hooked; curved like a scythe or sickle; falciform.
FALCIFORM: Sickle-shaped; falcate.
FALLOW: Plowed and left unseeded; left for a considerable time unworked or unseeded after tillage; untilled; uncultivated.
FALLS: The drooping or horizontal petals of irises.
FAMILY: This consists of genera (singular is genus, go see) that resemble one another in certain broad characteristics. The family usually consists of numerous genera, though some only consist of one. The family name usually ends with -aceae or -ae. For example, Compositae, which is the largest family of plants, consists of 950 genera and 20,000 species. Asters, Sunflowers, Mums, and Dahlias are all well-known members of that family and these genera contain numerous species.
FAN-TRAINING: A method of training a tree or vine on a trellis or wall in a way that causes the branches radiate from the trunk at regular intervals and at continually smaller angles, the lower branch on each side being horizontal.
FARINOSE: Covered with mealy powder (i.e. leaves of certain plants
FASCIATE: Banded or compacted together; exhibiting fasciation. Also fasciated.
FASCIATION: A malformation in plants, in which a stem or branch becomes expanded into a flat, ribbon-like shape, as if several stems were joined together lengthwise.
FASCICLE: A close cluster or bundle, as of leaves, stems, or flowers. Sometimes limited in use to a compacted cyme.
FASTIGIATE: With erect branches and close together.
FASTIGIATE TREES: Trees grown for their narrow, columnar shape.
FAVEOLATE: Honeycombed; alveolate. In botany, also favose.