Botany Terms Starting With F

Fertilization in plants is the fusion of a male sperm cell with a female egg cell inside the ovule, producing a zygote that develops into an embryo.

In flowering plants, the pollen tube germinates from a pollen grain on the stigma, grows through the style guided by chemical signals from synergid cells, and delivers two non-motile sperm cells directly into the embryo sac. One sperm fuses with the egg cell to form the diploid zygote, while the second fuses with two polar nuclei to form the triploid primary endosperm nucleus, a process unique to angiosperms called double fertilization. This double fertilization was first described by the Russian botanist Sergei Nawaschin in 1898, working with lily (Lilium) and fritillary (Fritillaria) flowers.

The endosperm produced by the second fusion event nourishes the developing embryo and, in grains such as wheat (Triticum aestivum), forms the starchy tissue that humans consume as food.

Filament is the slender stalk of a stamen that supports the anther and positions it for pollen dispersal.

Filament length varies from nearly absent in some flowers to several centimeters in others, directly determining whether anthers remain enclosed within the corolla or project beyond it. In Easter lily (Lilium longiflorum), filaments extend 5 to 7 centimeters, positioning the anthers well outside the perianth where visiting insects and air currents contact pollen readily. Filament tissue contains xylem and phloem that supply water and nutrients to the metabolically active anther above, supporting the energy-intensive process of meiosis and pollen maturation.

The angle and rigidity of the filament also influence pollen presentation timing; in some sage species (Salvia), a lever mechanism involving the filament deposits pollen precisely on the back of a visiting bee.

Floral ovary is the enlarged basal portion of the pistil that encloses one or more ovules and typically develops into a fruit after fertilization.

The position of the ovary relative to the attachment points of sepals, petals, and stamens is a key character in plant classification. A superior ovary sits above these attachments, as in tulips (Tulipa) and tomatoes (Solanum lycopersicum), while an inferior ovary sits below them, embedded in the receptacle, as in apples (Malus domestica) and cucumbers (Cucumis sativus). The ovary wall, called the pericarp, may be thin and papery as in peas, fleshy as in peaches, or hard and woody as in walnuts, depending on the species.

Each ovary contains one or more carpels, and the number and arrangement of carpels determines the internal compartment structure, called locules, visible when a fruit is cut in cross-section.

Floral symmetry describes the geometric arrangement of a flower's parts, specifically whether the flower can be divided into mirror-image halves along multiple planes, as in a buttercup, or along only one plane, as in a snapdragon.

A flower divisible into equal halves along any vertical plane through its center is called actinomorphic or radially symmetrical, a condition seen in tulips, roses, and cherry blossoms. When only a single vertical plane produces mirror halves, the flower is called zygomorphic or bilaterally symmetrical, as in orchids, violets, and mints. Zygomorphic flowers often restrict pollinator access to a specific approach angle, increasing the precision of pollen placement on the pollinator’s body and reducing pollen waste.

Evolutionary transitions from actinomorphic to zygomorphic flowers have occurred independently in at least 25 angiosperm lineages, and genetic studies show that a small number of transcription factor genes, including CYCLOIDEA in the snapdragon family, control the shift between the two symmetry types.

Flower is the reproductive structure of angiosperms, bearing the organs that produce pollen, ovules, or both, and that generate seeds following pollination and fertilization.

A complete flower carries four whorls on a receptacle: the calyx of sepals that protects the unopened bud, the corolla of petals that attracts pollinators through color and scent, the androecium of stamens that produces pollen, and the gynoecium of one or more carpels that encloses the ovules. Petals in many species reflect ultraviolet wavelengths visible to bees but not to humans, creating nectar guides that direct pollinators toward the nectary. In cherry trees (Prunus serrulata), flowers open weeks before leaves expand, concentrating pollinator visits on the reproductive organs before foliage competes for attention.

Some flowers, such as those of the titan arum (Amorphophallus titanum), generate heat through a process called thermogenesis, raising their temperature up to 10 degrees Celsius above ambient air to volatilize scent compounds and attract carrion-feeding insects.

Frond is the large leaf of a fern or palm, often pinnately divided into many leaflets and bearing the photosynthetic and, in ferns, reproductive surfaces of the plant.

Fern fronds begin as tightly coiled structures called fiddleheads that unroll through a process called circinate vernation as the leaf expands over days to weeks. Bracken fern (Pteridium aquilinum) produces fronds reaching 2 to 4 meters in height, with two to three levels of pinnate divisions that maximize photosynthetic surface area on shaded forest floors. On the undersides of fertile fronds, sporangia cluster into groups called sori, each sorus containing dozens to hundreds of individual sporangia that collectively release millions of spores per frond per season.

Unlike the leaves of flowering plants, fern fronds lack flowers and fruits entirely, reproducing instead through spores that germinate into a separate, free-living gametophyte generation.

Fruit is the mature ovary of a flowering plant that develops after fertilization and encloses one or more seeds within a pericarp derived from the ovary wall.

Fruits develop from the ovary wall, or pericarp, following fertilization, and botanists classify them as either fleshy or dry based on pericarp texture at maturity. Fleshy types include berries, drupes, and pomes, while dry types include achenes, capsules, legumes, and nuts. Tomato fruits develop from the ovary and can reach up to 300 grams, with succulent tissue protecting seeds inside.

Dry fruits such as the legumes of garden peas split along two sutures to release seeds directly, while fleshy fruits such as apples attract animals that disperse seeds after consumption. Wings on maple samaras aid wind dispersal, and hooked burs on burdock catch animal fur, demonstrating how pericarp structure shapes dispersal strategy.