Flowers - An Overview

A flower, (<Old French flo(u)r<Latin florem<flos), also known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called sperms). The flower structure contains the plant's organs, and its function is to produce seeds through reproduction. For the higher plants, seeds are the next generation, and serve as the primary means by which individuals of a species are dispersed across the landscape. After fertilization, portions of the flower develop into a fruit containing the seeds.

Types of Flowers

• Rose
• Tulip
• Lily
• Sunflower
• Freesia
• Gerbera
• Hibiscus
• Peony
• Sweet pea
• Hydrangea
• Amaryllis
• Curcuma
• Protea
• Anemone
• Bird of Paradise
• Carnation

Evolution of flowers

While land plants have existed for about 425 million years, the first ones reproduced by a simple adaptation of their aquatic counterparts; spores. In the sea, plants -- and some animals -- can simply scatter out little living copies of themselves to float away and grow elsewhere. This is how early plants are thought to have, like modern ferns, reproduced. But plants soon began protecting these copies to deal with drying out and other abuse which is even more likely on land than in the sea. The protection became the seed...but not, yet, flowers. Early seed-bearing plants include the ginko, conifers (like pines), and fir trees. But the first fossil proof of actual flowers appears only 130 million years ago.

Unfortunately, there is no fossil evidence of exactly how flowers evolved; the evidence has them springing in advanced form into the fossil record. This was recognized almost immediately during the development of evolution theory, the strange appearance of flowers in the fossil record being called by Charles Darwin the Abominable Mystery.

The general assumption is that the function of flowers, from the start, was to involve other animals in the reproduction process. Pollen can be scattered without bright colors and obvious shapes, which would therefore be a liability, using the plant's resources, unless they provide some other benefit. One proposed reason for the sudden, fully developed appearance of flowers is that they evolved in an isolated setting like an island, or chain of islands, where the plants bearing them were able to develop a highly specialized relationship with some specific animal (a wasp, for example), the way many island species develop today. This symbiotic relationship, with a hypothetical wasp bearing pollen from one plant to another much the way fig wasps do today, could have eventually resulted in both the plant(s) and their partners developing a high degree of specialization. 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. Note that the wasp example is not incidental; bees, apparently evolved specifically for symbiotic plant relationships, are descended from wasps.

Likewise, most fruit used in plant reproduction comes from the enlargement of parts of the flower. This fruit is frequently a tool which depends upon animals wishing to eat it, and thus scattering the seeds it contains.

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

While there is only hard proof of such flowers existing about 130 million years ago, there is some circumstantial evidence that they did exist up to 250 million years ago. A chemical used by plants to defend their flowers, oleanane, has been detected in fossil plants that old, including gigantopterids, which evolved at that time and bear many of the traits of modern, flowering plants, though they are not known to be flowering plants themselves, because only their stems and prickles have been found preserved in detail; one of the earliest examples of petrification.

The similarity in leaf and stem structure can be very important, because flowers are genetically just an adaptation of normal leaf and stem components on plants, a combination of genes normally responsible for forming new shoots. The most primitive flowers are thought to have had a variable number of flower parts, often separate from (but in contact with) each other. The flowers would have tended to grow in a spiral pattern, to be bisexual (in plants, this means both male and female parts on the same flower), and to be dominated by the ovary (female part). As flowers grew more advanced, some variations developed parts fused together, with a much more specific number and design, and with either specific sexes per flower or plant, or at least "ovary inferior".

Flower evolution continues to the present day; modern flowers have been so profoundly influenced by humans that many of them cannot be pollinated in nature. Many modern, domesticated flowers used to be simple weeds, which only sprouted when the ground was disturbed. Some of them tended to grow with human crops, and the prettiest did not get plucked because of their beauty, developing a dependence upon and special adaptation to human affection.