Fertile (fertilis). Capable of producing progeny, especially bearing pollen or ovules which develop into seeds.
Filament (filamentum). The lower narrow part (the stalk) of the stamen.
Filiform (filiformis). Thread-shaped, i.e., cylindrical and very slender.
Flexuous (flexuosus). Bent alternately in opposite directions.
Foliaceous (foliaceus). Leaf-like, i.e., having the shape and texture of a foliage-leaf.
Foliole (foliolum). Leaflet, i.e., one of the leaf-like parts of a compound leaf, which are jointed to the rachis.
Follicle (folliculus). A one-celled fruit opening lengthwise (at the ventral suture).
Forked (furcatus). Divided into two subequal branches.
Free (liber). Not united, not even at the base.
Funicle (funiculus). The stalk of the ovule.