falcate (1 image): sickle-shaped; curved like a hawk's beak.

farina: mealy- or powderylike covering, often on the underside of leaves.

farinose: covered with a meal-like powder.

fascicle (5 images): a close bundle or cluster.

fastigiate: crowded close together, more or less parallel, and generally erect.

fellfield: windblown alpine or tundra slopes or scree fields dominated by low-growing plants.

fenestrate: with 1 or more window-like openings.

ferruginous (1 image): rust-colored.

fibrillose: covered with hairlike appendages.

filament (3 images): the stalk of a stamen.

filiform (1 image): very slender, thread-like.

fimbriate (3 images): fringed.

fistulose (fistulous): hollow.

flabellate: fan-shaped.

flabelliform: same as flabellate.

flaccid: weak and lax, hardly if at all capable of supporting its own weight.

fleshy (1 image): thick and juicy.

floccose: covered with very long, soft, loosely spreading and more or less tangled hairs.

floret (3 images): a little flower; an individual flower of a definite cluster.

foliaceous: leafy in texture.

foliose: leafy.

follicle (6 images): a dry fruit composed of 1 carpel, which at maturity dehisces along the seed-bearing suture only.

fornix (4 images): one of a set of small scales or appendages in the tube or throat of the corolla of some flowers, common in Boraginaceae.

fovea (1 image): a little pit.

free (3 images): not fused (adnate) to other organs.

free-central placenta: one consisting of a free-standing column or projection from the base of a compound, 1-celled ovary.

frutescent: shrublike or shrubby.

fruit (1 image): a ripened ovary, together with any other structures that ripen with it and form a unit with it.

fugacious: fleeting; lasting only a short time.

fulvous: tawny, dull yellow.

fuscous: gray-brown.

fusiform: spindle-shaped.