Parts of FlowersFlowers are beautiful to us, but for the plant they serve a critical function. Flowers are how plants produce seeds to reproduce. In many cases, the flower contains male and female parts, roughly equivalent to the male and female sexes of animals. The male parts of the flower are called the stamens and are made up of the anther at the top and the stalk or filament that supports the anther. The female elements are collectively called the pistil. The top of the pistil is called the stigma, which is a sticky surface receptive to pollen. The bottom of the pistil contains the ovary and the narrowed region in between is called the style. The male contribution or pollen is produced in the anther, and seeds develop in the ovary. Many of the fruits we eat are the thickened ovary walls surrounding the seeds. Show
Not only does the flower contain the sexual parts necessary for reproduction, they are also like flashy roadside billboards advertising a rich supply of nectar and pollen ready and waiting for pollinating insects and other creatures. That is the bargain offered. Flowers trade rewards (in the form of sugary nectar and pollen) in return for the service that insects and other pollinators perform. Pollination is simply the transfer of pollen grains from an anther to a stigma. Fertilization occurs much later when the pollen grains germinate on the stigma and send down a pollen tube which releases the sex cells to fertilize the ovules. After fertilization, the ovules become the seeds, and the ovary wall becomes the fruit. The sexual nature of flowers and the role of the many forms, colors and scents in attracting pollinators was discovered in 1759 by Arthur Dobbs. Angiosperms. Flowering plants that have a condensed shoot tip specialized for reproduction. Anthers. The bright yellow sacs that produce and contain the pollen grains. Composites. Flowers such as daisies, sunflowers and their relatives that are made up of lots of tiny flowers but look just like a single flower. Filament. The thin stalk that supports the anther in the male portion of the flower. Gametes. The sex cells of a flower, both male and female. The gametes are porduced within the anthers of the male part and the ovary of the female part of the flower. Gymnosperms. Plants that produce seeds without flowers, such as conifers. Nectar. A sugary liquid reward for pollinators that is produced by the nectaries. Nectaries. The tissue at the base of a flower (or elsewhere) that secrete nectar. Some plants, such as cotton, have nectaries on the leaves or stems. These are called extrafloral nectaries, and may serve to attract beneficial insects. An example is the extrafloral nectaries of peonies (a flower) that attract ants that in turn protect the unopened flower buds from caterpillars. Ovary. The base of the female portion of the flower containing the ovules which become seeds. Perfect flower. Perfect flowers contain both the male parts and female parts within a single flower structure. Petals. The colorful, thin structures that surround the sexual parts of the flower. Not only attract pollinators, but also protect the pistil and stamen. May also produce a scent. Pollen grains. The powdery particles that contain the male sex cells (gametes). Also a nutritious, protein-rich food for bees. Pollination. The act of transferring pollen from the anther to the stigma. The pollen may be carried by the wind or water, but is usually transported by a go-between insect, bird or bat. Sepals. Commonly green, leaflike structures that protect the bud prior to opening. Stamen. Male part of flower consisting of anther and filament. Stigma. Sticky surface where the pollen lands and germinates.
 Return to homepageAngiosperms, which evolved in the Cretaceous period, are a diverse group of plants which protect their seeds within an ovary called a fruit. Key Points
Key Terms
Evolution of AngiospermsUndisputed fossil records place the massive appearance and diversification of angiosperms in the middle to late Mesozoic era. Angiosperms (“seed in a vessel”) produce a flower containing male and/or female reproductive structures. Fossil evidence indicates that flowering plants first appeared in the Lower Cretaceous, about 125 million years ago, and were rapidly diversifying by the Middle Cretaceous, about 100 million years ago. Earlier traces of angiosperms are scarce. Fossilized pollen recovered from Jurassic geological material has been attributed to angiosperms. A few early Cretaceous rocks show clear imprints of leaves resembling angiosperm leaves. By the mid-Cretaceous, a staggering number of diverse, flowering plants crowd the fossil record. The same geological period is also marked by the appearance of many modern groups of insects, including pollinating insects that played a key role in ecology and the evolution of flowering plants. Although several hypotheses have been offered to explain this sudden profusion and variety of flowering plants, none have garnered the consensus of paleobotanists (scientists who study ancient plants). New data in comparative genomics and paleobotany have, however, shed some light on the evolution of angiosperms. Rather than being derived from gymnosperms, angiosperms form a sister clade (a species and its descendents) that developed in parallel with the gymnosperms. The two innovative structures of flowers and fruit represent an improved reproductive strategy that served to protect the embryo, while increasing genetic variability and range. Paleobotanists debate whether angiosperms evolved from small woody bushes, or were basal angiosperms related to tropical grasses. Both views draw support from cladistic studies. The so-called woody magnoliid hypothesis (which proposes that the early ancestors of angiosperms were shrubs) also offers molecular biological evidence. The most primitive living angiosperm is considered to be Amborellatrichopoda, a small plant native to the rainforest of New Caledonia, an island in the South Pacific. Analysis of the genome of A. trichopoda has shown that it is related to all existing flowering plants and belongs to the oldest confirmed branch of the angiosperm family tree. A few other angiosperm groups, known as basal angiosperms, are viewed as primitive because they branched off early from the phylogenetic tree. Most modern angiosperms are classified as either monocots or eudicots based on the structure of their leaves and embryos. Basal angiosperms, such as water lilies, are considered more primitive because they share morphological traits with both monocots and eudicots. Flowers and Fruits as an Evolutionary AdaptationAngiosperms produce their gametes in separate organs, which are usually housed in a flower. Both fertilization and embryo development take place inside an anatomical structure that provides a stable system of sexual reproduction largely sheltered from environmental fluctuations. Flowering plants are the most diverse phylum on Earth after insects; flowers come in a bewildering array of sizes, shapes, colors, smells, and arrangements. Most flowers have a mutualistic pollinator, with the distinctive features of flowers reflecting the nature of the pollination agent. The relationship between pollinator and flower characteristics is one of the great examples of coevolution. Following fertilization of the egg, the ovule grows into a seed. The surrounding tissues of the ovary thicken, developing into a fruit that will protect the seed and often ensure its dispersal over a wide geographic range. Not all fruits develop from an ovary; such structures are “false fruits.” Like flowers, fruit can vary tremendously in appearance, size, smell, and taste. Tomatoes, walnut shells and avocados are all examples of fruit. As with pollen and seeds, fruits also act as agents of dispersal. Some may be carried away by the wind. Many attract animals that will eat the fruit and pass the seeds through their digestive systems, then deposit the seeds in another location. Cockleburs are covered with stiff, hooked spines that can hook into fur (or clothing) and hitch a ride on an animal for long distances. The cockleburs that clung to the velvet trousers of an enterprising Swiss hiker, George de Mestral, inspired his invention of the loop and hook fastener he named Velcro. Contributions and Attributions
What does the ovule develop into in angiosperms?In angiosperms (flowering plants), one or more ovules are enclosed by the ovary, which develops into the fruit.
What does the ovary develops into?The ovary contains ovules, which develop into seeds upon fertilization. The ovary itself will mature into a fruit, either dry or fleshy, enclosing the seeds. A simple or unicarpellate ovary is formed from a single carpel, an evolutionarily modified leaf.
What happens to the angiosperm ovary during development of the seed?As the seed develops, the walls of the ovary thicken and form the fruit. The seed forms in an ovary, which also enlarges as the seeds grow. In botany, a fertilized and fully grown, ripened ovary is a fruit.
Have seeds that are enclosed in an ovary that develops into a fruit like flowers?Angiosperms, also called flowering plants, have seeds that are enclosed within an ovary (usually a fruit), while gymnosperms have no flowers or fruits, and have unenclosed or “naked” seeds on the surface of scales or leaves.
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Angiosperm ovules are enclosed inside the ovary, which develops into the ______.
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