Glossary: F

FAC: Facultative: plant is equally likely to occur in wetlands or non-wetlands (probability 34%-66%).
FAC-: Facultative: plant is equally likely to occur in wetlands or non-wetlands (probability 34%-66%). Minus sign indicates tendency toward the lower end of the category (less frequently found in wetlands).
FAC+: Facultative: plant is equally likely to occur in wetlands or non-wetlands (probability 34%-66%). Plus sign indicates tendency toward the higher end of the category (more frequently found in wetlands).
FACU: Facultative Upland: plant usually occurs in non-wetlands (probability 67-99%), but occasionally found in wetlands (probability 1%-33%).
FACU-: Facultative Upland: plant usually occurs in non-wetlands (probability 67-99%), but occasionally found in wetlands (probability 1%-33%). Minus sign indicates tendency toward the lower end of the category (less frequently found in wetlands).
FACU+: Facultative Upland: plant usually occurs in non-wetlands (probability 67-99%), but occasionally found in wetlands (probability 1%-33%). Plus sign indicates tendency toward the higher end of the category (more frequently found in wetlands).
FACW: Facultative Wetland: plant usually occurs in wetlands (probability 67%-99%), but occasionally found in non-wetlands.
FACW-: Facultative Wetland: plant usually occurs in wetlands (probability 67%-99%), but occasionally found in uplands. Minus sign indicates tendency toward the lower end of the category (less frequently found in wetlands).
FACW+: Facultative Wetland: plant usually occurs in wetlands (probability 67%-99%), but occasionally found in uplands. Plus sign indicates tendency toward the higher end of the category (more frequently found in wetlands).
falcate: Sickle-shaped.
false indusium: A flap of unspecialized tissue, such as an inrolled leaf edge, that covers and protects the sorus of a fern.
family: The grouping in a taxonomic hierarchy that encompasses related genera.
farina: Inflated hairs that create a mealy coating on a surface.
farinose: With a mealy coating.
fascicle: Compact cluster.
fasciculate: With leaflets or needles in a bundle or compact cluster.
fenestrate: With openings or window-like slits.
fern: A non-flowering plant that produces spores, which themselves germinate to form sexual plantlets whose offspring in turn become the spore-bearing plant.
fibrillose: Separating into fibers (fibrous).
filament: The stalk supporting the pollen-bearing structure (anther).
filiform: Thread-like.
fimbriate: Fringed.
flabellate: Fan-shaped.
fleshy: Succulent, with a high water content.
flexuous: Sinuous, curving alternately in different directions.
floret: The ultimate unit of the spikelet of the Poaceae, consisting of a flower and usually two subtending the scales (lemma, palea).
floret: Small or single flower (flower plus lemma and palea in Poaceae).
floricane: Second-year flowering stem of Rubus (compare "primocane").
floriferous: Bearing flowers.
flower: The reproductive structure of a plant.
foliaceous: Leaf-like.
foliose: Like a leaf in form or texture.
follicle: A dehiscent fruit with a single ovary, that splits along a single seam on one side of the mature carpel to release the seeds.
forb: Herbaceous plant usually less than 2 meters (6 feet) tall.
fork: A vein that branches.
fornix: A scale or appendage in the corolla tube of some Boraginaceae.
free: Not fused with another dissimilar structure, such as stamens that are not connected with petals.
frond: The leafy part of a fern, including the stipe (petiole) and blade (pinnae).
fruit: The mature or ripened ovary and any associated structures that ripen and unite with it.
funneliform: Shaped like a flaring tube (funnel).
furrow: Longitudinal groove or channel.
fusiform: Narrowly tapering at both ends and fat in the middle (spindle-shaped).