Flower

[2] Most flowering plants depend on animals, such as bees, moths, and butterflies, to transfer their pollen between different flowers, and have evolved to attract these pollinators by various strategies, including brightly colored, large petals with patterns only visible to under ultraviolet light, attractive scents, and the production of nectar, a food source for pollinators.

[2] Flowers have long been appreciated for their beauty and pleasant scents, and also hold cultural significance as religious, ritual, or symbolic objects, or sources of medicine and food.

A stereotypical flower is made up of four kinds of structures arranged in whorls around the tip of a short stalk or axis, called a receptacle.

[11][2] The four main whorls (starting from the base of the flower or lowest node and working upwards) are the calyx, corolla, androecium, and gynoecium.

[13] The petals, collectively called corolla, are almost or completely fiberless leaf-like structures that form the innermost whorl of the perianth.

The use of schematic diagrams can replace long descriptions or complicated drawings as a tool for understanding both floral structure and evolution.

The molecular interpretation of these signals is through the transmission of a complex signal known as florigen, which involves a variety of genes, including Constans, Flowering Locus C, and Flowering Locus T. Florigen is produced in the leaves in reproductively favorable conditions and acts in buds and growing tips to induce several different physiological and morphological changes.

Three gene activities interact in a combinatorial manner to determine the developmental identities of the primordia organ within the floral apical meristem.

[48] Flowers use animals including: insects (entomophily), birds (ornithophily), bats (chiropterophily), lizards,[51] and even snails and slugs (malacophilae).

[68] Flowers are also specialized in shape and have an arrangement of the stamens that ensures that pollen grains are transferred to the bodies of the pollinator when it lands in search of its attractant.

Because of this, plants typically have many thousands of tiny flowers which have comparatively large, feathery stigmas; to increase the chance of pollen being received.

[48][81] The principal adaptive function of flowers is the promotion of cross-pollination or outcrossing, a process that allows the masking of deleterious mutations in the genome of progeny.

Charles Darwin in his 1889 book The Effects of Cross and Self-Fertilization in the Vegetable Kingdom[83] at the beginning of chapter XII noted, "The first and most important of the conclusions which may be drawn from the observations given in this volume, is that generally cross-fertilisation is beneficial and self-fertilisation often injurious, at least with the plants on which I experimented."

This number appears to be growing, as the temperature increases due to climate change mean that plants are producing more pollen[citation needed], which is also more allergenic.

[92] Following the formation of zygote it begins to grow through nuclear and cellular divisions, called mitosis, eventually becoming a small group of cells.

This method falls under the umbrella term zoochory, while endozoochory, also known as fruigivory, refers specifically to plants adapted to grow fruit in order to attract animals to eat them.

[102][103] They can be eaten by birds (ornithochory), bats (chiropterochory), rodents, primates, ants (myrmecochory),[104] non-bird sauropsids (saurochory), mammals in general (mammaliochory),[102] and even fish.

Adaptations for this usually involve the fruits exploding and forcing the seeds away ballistically, such as in Hura crepitans,[111] or sometimes in the creation of creeping diaspores.

The apparently sudden appearance of relatively modern flowers in the fossil record posed such a problem for the theory of evolution that it was called an "abominable mystery" by Charles Darwin.

Island genetics is believed to be a common source of speciation, especially when it comes to radical adaptations which seem to have required inferior transitional forms.

While many such symbiotic relationships remain too fragile to survive competition with mainland organisms, flowers proved to be an unusually effective means of production, spreading (whatever their actual origin) to become the dominant form of land plant life.

Color may be modulated by shifting the transition point between absorption and reflection and in this way a flowering plant may specify which pollinator it seeks to attract.

[126] Antoine Laurent de Jussieu (1748–1836) was a French botanist whose 1787 work Genera plantarum: secundum ordines naturales disposita set out a new method for classifying plants; based instead on natural characteristics.

Plants were divided at the highest level by the number of cotyledons and the nature of the flowers, before falling into orders (families), genera, and species.

[128] Following the development in scientific thought after Darwin's On the Origin of Species, many botanists have used more phylogenetic methods and the use of genetic sequencing, cytology, and palynology has become increasingly common.

[137] In modern times, people have sought ways to cultivate, buy, wear, or otherwise be around flowers and blooming plants, partly because of their agreeable appearance and smell.

Some edible flowers include nasturtium, chrysanthemum, carnation, cattail, Japanese honeysuckle, chicory, cornflower, canna, and sunflower.

[142] Flowers such as chrysanthemum, rose, jasmine, Japanese honeysuckle, and chamomile, chosen for their fragrance and medicinal properties, are used as tisanes, either mixed with tea or on their own.

[143] Flowers have been used since prehistoric times in funeral rituals: traces of pollen have been found on a woman's tomb in the El Miron Cave in Spain.

In Egypt, burial objects from the time around 1540 BC[citation needed] were found, which depicted red poppy, yellow Araun, cornflower and lilies.