Flowering plant
Flowering plants, or angiosperms, represent the most diverse and ecologically dominant group of plants on Earth, vital to nearly every terrestrial ecosystem and human civilization itself. From the towering Eucalyptus to the minuscule Wolffia, they display an astonishing range of forms and adaptations. Their unique reproductive strategy, centered on the flower and enclosed seeds, truly unlocked an evolutionary explosion that continues to shape our world. Angiosperms are distinguished by their flowers, which enclose seeds within fruits, a key innovation driving their incredible success. They are the foundation of global food systems and provide numerous essential resources, making human civilization profoundly dependent on them. A remarkable coevolutionary dance with pollinators, coupled with diverse adaptations, allowed flowering plants to rapidly diversify and dominate nearly every habitat.
AI Summary
Flowering plants, or angiosperms, represent the most diverse and ecologically dominant group of plants on Earth, vital to nearly every terrestrial ecosystem and human civilization itself. From the towering Eucalyptus to the minuscule Wolffia, they display an astonishing range of forms and adaptations. Their unique reproductive strategy, centered on the flower and enclosed seeds, truly unlocked an evolutionary explosion that continues to shape our world.
- Angiosperms are distinguished by their flowers, which enclose seeds within fruits, a key innovation driving their incredible success.
- They are the foundation of global food systems and provide numerous essential resources, making human civilization profoundly dependent on them.
- A remarkable coevolutionary dance with pollinators, coupled with diverse adaptations, allowed flowering plants to rapidly diversify and dominate nearly every habitat.
Meet the Angiosperms: Earth's Floral Dynamos
Flowering plants are known scientifically as Angiospermae—a name rooted in ancient Greek, where 'angeion' means container or vessel, and 'sperma' means seed. This elegantly describes their defining characteristic: seeds enclosed within a protective fruit. You might remember them by their older name, Magnoliophyta, but angiosperm is the term you'll hear most often today.
These incredible plants are the undisputed champions of the plant kingdom. With an astonishing 300,000 known species, they vastly outnumber all other land plant groups combined. They encompass everything from the smallest aquatic duckweeds to the tallest trees, and from vibrant garden flowers to essential food crops.
What Makes a Flowering Plant Unique?
While all seed plants have roots, stems, leaves, and seeds, angiosperms stand apart from their cousins, the gymnosperms (like conifers), through several groundbreaking evolutionary features. These innovations paved the way for their global dominance and incredible adaptability.
Feature Description Flowers The unique reproductive organs of flowering plants, never seen in other seed plants. Reduced Gametophytes Smaller male and female reproductive structures lead to faster fertilization, often within days or weeks, compared to up to a year for gymnosperms. Endosperm A nutritive tissue that forms after fertilization, providing food for the developing embryo and seedling, a crucial energy reserve. Closed Carpel Ovules are enclosed within a carpel, which develops into the fruit after fertilization, completely enveloping the seeds. Xylem Vessel Elements Their water-conducting xylem tissue features vessel elements—efficient, continuous tubes—unlike the less efficient tapered tracheids found in gymnosperms.
The Unsung Heroes of Human Civilization
Our lives are inextricably linked to flowering plants. Agriculture, the very foundation of human society, relies almost entirely on angiosperms. Just three families—grasses (Poaceae), peas (Fabaceae), and nightshades (Solanaceae)—provide the bulk of our food.
Think about it: rice, maize, and wheat, all members of the grass family, supply half of the world's calorie intake. Beyond food, angiosperms give us wood, paper, cotton, countless ingredients for drinks, sugar, traditional medicines, and modern pharmaceuticals. And let's not forget the sheer beauty of ornamental flowers, which enrich our cultures and spirits worldwide.
A World of Diversity: Adapting to Every Niche
Giants and Miniatures
Flowering plants showcase an incredible range in size. Australia's Eucalyptus gum trees and Southeast Asia's Shorea rainforest trees can soar to nearly 100 meters (330 ft) tall. On the other end of the spectrum are the tiny Wolffia duckweeds, freshwater plants less than 2 millimeters across, barely visible to the naked eye.
From Sun Worshippers to Resource Pirates
Most flowering plants, about 99% of them, are photosynthetic autotrophs—they capture sunlight to create their own food, just like the broad-leaved Gunnera. But some have adopted a more unusual lifestyle.
The remaining 1% are parasitic. Some, like broomrapes, have no leaves and steal all their nutrients directly from other plants. Others, like certain orchids, are myco-heterotrophic, drawing resources from fungi for part or all of their life cycle. It's a testament to their evolutionary ingenuity!
Thriving in Extremes: Hot, Cold, Wet, Dry
Angiosperms are truly cosmopolitan, inhabiting almost every corner of the Earth. You'll find them flourishing in hot, dry deserts like the saguaro cactus, and in cold, arctic environments, such as the hardy mountain avens. They dominate most land habitats, with only frigid moss-lichen tundras and dense coniferous forests seeing fewer of them.
They've even conquered water. The sacred lotus graces warm freshwaters across Asia, while certain seagrasses have adapted to grow underwater in sheltered coastal marine environments, spreading through the seabed with their rhizomes.
Acid, Alkaline, and Everything in Between
Specialized angiosperms thrive in habitats with extreme soil chemistry. Carnivorous sundews, for example, flourish in nutrient-poor acid bogs, supplementing their diet by trapping and digesting insects. Conversely, the spring gentian is perfectly adapted to the alkaline, calcium-rich soils found in limestone areas.
Herbs, Trees, and Climbers
Their growth habits are just as varied. You'll find delicate herbaceous annuals and biennials, like herb-Robert, that complete their life cycle in one or two seasons. Then there are long-lived, massive woody perennial trees, such as the silver birch, that can live for centuries. Some, like the lianas, don't even bother growing a strong trunk, instead climbing other plants to reach the sunlight.
An Evolutionary Masterpiece: The Flower
The flower is the defining characteristic of an angiosperm—a marvel of biological engineering designed to ensure the fertilization of ovules and the subsequent development of seeds encased in fruit. These beautiful structures can appear at the end of a shoot or from a leaf's axil, often forming complex arrangements called inflorescences.
Within the flower, two types of reproductive cells are produced: microspores, which develop into pollen grains (the male cells, borne in stamens), and megaspores, which become the egg cell (contained within the ovule, enclosed by the carpel). Sometimes, simple flowers, like those of wind-pollinated willows, consist of just these essential parts.
For plants that rely on animals for pollination, flowers feature additional structures. Sepals form the outer, often green, protective layer of the bud. Petals, usually brightly colored and fragrant, attract pollinators with their visual appeal, scent, and nectar. In some flowers, like the magnolia, sepals and petals are indistinguishable, called tepals.
Most flowers are hermaphroditic, meaning they contain both male and female parts. However, many have clever strategies to prevent self-fertilization, which can reduce genetic diversity. Some have physically separated male and female parts of different lengths. Others use biochemical self-incompatibility to recognize and reject their own pollen.
Some plants take it further: dioecious species, like holly, have separate male and female flowers on entirely different plants. Monoecious plants, such as maize, bear distinct male and female flowers on the same plant, often relying on wind for pollination, or sometimes insects, as seen in squashes.
The Miracle of Double Fertilization
One of the most remarkable processes in angiosperm reproduction is double fertilization, a unique event requiring two sperm cells. It begins when a pollen grain lands on the stigma, germinates, and grows a long pollen tube down into the ovary. This tube delivers two haploid sperm cells to an ovule.
Here's where the 'double' comes in: one sperm fertilizes the egg cell, forming a diploid zygote that will become the embryo. The second sperm fuses with two central cell nuclei, creating a triploid cell. This triploid cell develops into the endosperm, which acts as a nutrient-rich food supply for the developing embryo. Meanwhile, the entire ovary matures into a fruit, with each ovule transforming into a seed.
Fruit and Seed: Nature's Clever Packages
As the embryo and endosperm grow, the ovule's outer layers harden, forming the protective seed coat. Simultaneously, the ovary wall undergoes a remarkable transformation, developing into the pericarp—the fruit itself. The fruit's form is intricately linked to how the seeds will be dispersed, whether by wind, water, or animals.
Sometimes, other flower parts join the party! In an apple, for instance, the fleshy, edible part we enjoy isn't just the ripened ovary; it's largely formed from the hypanthium, a floral cup, surrounding the central core of tough, seed-containing ovary tissue.
While fertilization is usually required, some angiosperms, like certain citrus varieties, can reproduce through apomixis, meaning they can produce seeds without fertilization. This allows them to create genetic clones of themselves, a fascinating bypass of the typical sexual reproduction cycle.
A Deep Dive into Angiosperm Evolution
A Shifting View: History of Classification
The journey to understand angiosperms taxonomically has been a long one. The term 'angiosperm' itself was coined by Paul Hermann in 1690, though its meaning has evolved. Initially, it described plants with seeds enclosed in capsules. Robert Brown later broadened it to any seed plant with enclosed ovules.
The modern understanding, encompassing all flowering plants (monocots and dicots), solidified with Wilhelm Hofmeister's work in 1851. Today, the Angiosperm Phylogeny Group (APG) continuously refines the classification using molecular phylogenetics, grouping plants by their genetic relationships. The most recent system, APG IV (2016), recognizes 64 orders and 416 families of angiosperms, constantly updating our family tree of life.
The 'Abominable Mystery' and Explosive Diversification
For a long time, the sudden appearance of flowering plants in the fossil record, particularly in the Early Cretaceous period (around 130 million years ago), was a puzzle Charles Darwin famously called an 'abominable mystery.' While molecular evidence suggests their ancestors diverged from gymnosperms much earlier—perhaps 365 million years ago—their rapid diversification in the Cretaceous is undeniable.
This 'Cretaceous Terrestrial Revolution' saw angiosperms quickly become the dominant plant group, replacing conifers as the primary canopy-forming trees by the late Cretaceous. This explosive radiation was a game-changer for Earth's ecosystems, setting the stage for the world we know today.
Coevolution: The Secret to Their Success
A major driver of angiosperm success is their incredible coevolutionary relationship with animal pollinators, especially insects, birds, and bats. Unlike wind-reliant gymnosperms, flowering plants developed specialized traits to attract specific visitors: vibrant colors, alluring scents, and sugary nectar.
This mutualism led to 'pollination syndromes,' where a flower's shape, size, and even scent perfectly match its primary pollinator. Think of tube-shaped flowers perfectly suited for hummingbirds' long beaks. This precise fit ensures efficient pollination and even contributes to the formation of new species by promoting reproductive isolation—a brilliant evolutionary strategy.
Article
Flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words ἀγγεῖον (angeion; 'container, vessel') and σπέρμα (sperma; 'seed'), meaning that the seeds are enclosed within a fruit. The group was formerly called Magnoliophyta.
Angiosperms are by far the most diverse group of land plants with 64 orders, 416 families, approximately 13,000 known genera and 300,000 known species. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of broad-leaved trees, shrubs and vines, and most aquatic plants. Angiosperms are distinguished from the other major seed plant clade, the gymnosperms, by having flowers, xylem consisting of vessel elements instead of tracheids, endosperm within their seeds, and fruits that completely envelop the seeds. The ancestors of flowering plants diverged from the common ancestor of all living gymnosperms before the end of the Carboniferous, over 300 million years ago. In the Cretaceous, angiosperms diversified explosively, becoming the dominant group of plants across the planet.
Agriculture is almost entirely dependent on angiosperms, and a small number of flowering plant families supply nearly all plant-based food and livestock feed. Rice, maize and wheat provide half of the world's staple calorie intake, and all three plants are cereals from the Poaceae family (colloquially known as grasses). Other families provide important industrial plant products such as wood, paper and cotton, and supply numerous ingredients for drinks, sugar production, traditional medicine and modern pharmaceuticals. Flowering plants are commonly grown for decorative purposes, with certain flowers playing significant cultural roles in many societies. Many flowering plants are threatened by habitat destruction and by climate change.
Distinguishing features
Flowering plant
Angiosperms are terrestrial vascular plants; like the gymnosperms, they have roots, stems, leaves, and seeds. They differ from other seed plants in several ways.
<table><thead><tr><th>Feature</th><th>Description</th><th>Image</th></tr></thead><tbody><tr><td>Flowers</td><td>The reproductive organs of flowering plants, not found in any other seed plants.</td><td></td></tr><tr><td>Reduced gametophytes, three cells in male, seven cells with eight nuclei in female (except for basal angiosperms)</td><td>The gametophytes are smaller than those of gymnosperms. The smaller size of the pollen reduces the time between pollination and fertilization, which in gymnosperms is up to a year.</td><td></td></tr><tr><td>Endosperm</td><td>Endosperm forms after fertilization but before the zygote divides. It provides food for the developing embryo, the cotyledons, and sometimes the seedling.</td></tr><tr><td>Closed carpel enclosing the ovules.</td><td>Once the ovules are fertilised, the carpels, often with surrounding tissues, develop into fruits. Gymnosperms have unenclosed seeds.</td><td></td></tr><tr><td>Xylem made of vessel elements</td><td>Open vessel elements are stacked end to end to form continuous tubes, whereas gymnosperm xylem is made of tapered tracheids connected by small pits.</td><td></td></tr></tbody></table>
Diversity
Ecological diversity
• Largest and smallest • Eucalyptus regnans, a tree almost 100 m tall • Wolffia arrhiza, a rootless floating freshwater plant under 2 mm across
The largest angiosperms are Eucalyptus gum trees of Australia, and Shorea faguetiana, dipterocarp rainforest trees of Southeast Asia, both of which can reach almost 100 metres (330 ft) in height. The smallest are Wolffia duckweeds which float on freshwater, each plant less than 2 millimetres (0.08 in) across.
• Photosynthetic and parasitic • Gunnera captures sunlight for photosynthesis over the large surfaces of its leaves, which are supported by strong veins. • Orobanche purpurea, a parasitic broomrape with no leaves, obtains all its food from other plants.
Considering their method of obtaining energy, some 99% of flowering plants are photosynthetic autotrophs, deriving their energy from sunlight and using it to create molecules such as sugars. The remainder are parasitic, whether on fungi (myco-heterotrophic, formerly thought to be saprophytic) like the orchids for part or all of their life-cycle, or on other plants, either wholly like the broomrapes, Orobanche, or partially like the witchweeds, Striga.
• Hot, cold, wet, dry, fresh, salt • Carnegiea gigantea, the saguaro cactus, grows in hot dry deserts in Mexico and the southern United States. • Dryas octopetala, the mountain avens, lives in cold arctic and montane habitats in the far north of America and Eurasia. • Nelumbo nucifera, the sacred lotus, grows in warm freshwater across tropical and subtropical Asia. • Zostera seagrass grows on the seabed in sheltered coastal waters.
In terms of their environment, flowering plants are cosmopolitan, occupying a wide range of habitats on land, in fresh water and in the sea. On land, they are the dominant plant group in every habitat except for frigid moss-lichen tundra and coniferous forest. The seagrasses in the Alismatales grow in marine environments, spreading with rhizomes that grow through the mud in sheltered coastal waters.
• Acid, alkaline • Drosera anglica, a sundew, lives in nutrient-poor acid bogs, deriving nutrients from trapped insects. • Gentiana verna, the spring gentian, flourishes in dry limestone habitats.
Some specialised angiosperms are able to flourish in extremely acid or alkaline habitats. The sundews, many of which live in nutrient-poor acid bogs, are carnivorous plants, able to derive nutrients such as nitrate from the bodies of trapped insects. Other flowers such as Gentiana verna, the spring gentian, are adapted to the alkaline conditions found on calcium-rich chalk and limestone, which give rise to often dry topographies such as limestone pavement.
• Herbaceous, woody, climbing • Geranium robertianum, herb-Robert, is an annual or biennial herb of Europe and North America. • Betula pendula, the silver birch, is a perennial deciduous tree of Eurasia. • Lianas Austrosteenisia, Parsonsia, and Sarcopetalum climbing trees in Australia
As for their growth habit, the flowering plants range from small, soft herbaceous plants, often living as annuals or biennials that set seed and die after one or two growing seasons, to large perennial woody trees that may live for many centuries and grow to many metres in height. Some species grow tall without being self-supporting like trees by climbing on other plants in the manner of vines or lianas.
Taxonomic diversity
The number of species of flowering plants is estimated to be in the range of 250,000 to 400,000. This compares to around 12,000 species of moss and 11,000 species of pteridophytes. The APG system seeks to determine the number of families, mostly by molecular phylogenetics. In the 2009 APG III there were 415 families. The 2016 APG IV added five new orders (Boraginales, Dilleniales, Icacinales, Metteniusales and Vahliales), along with some new families, for a total of 64 angiosperm orders and 416 families.
The diversity of flowering plants is not evenly distributed. Nearly all species belong to the eudicot (75%), monocot (23%), and magnoliid (2%) clades. The remaining five clades contain a little over 250 species in total; i.e. less than 0.1% of flowering plant diversity, divided among nine families. The 25 most species-rich of 443 families, containing over 166,000 species between them in their APG circumscriptions, are:
<table><thead><tr><th></th><th>Group</th><th>Family</th><th>English name</th><th>No. of spp.</th></tr></thead><tbody><tr><td>1</td><td>Eudicot</td><td>Asteraceae or Compositae</td><td>daisy</td><td>22,750</td></tr><tr><td>2</td><td>Monocot</td><td>Orchidaceae</td><td>orchid</td><td>21,950</td></tr><tr><td>3</td><td>Eudicot</td><td>Fabaceae or Leguminosae</td><td>pea, legume</td><td>19,400</td></tr><tr><td>4</td><td>Eudicot</td><td>Rubiaceae</td><td>madder</td><td>13,150</td></tr><tr><td>5</td><td>Monocot</td><td>Poaceae or Gramineae</td><td>grass</td><td>10,035</td></tr><tr><td>6</td><td>Eudicot</td><td>Lamiaceae or Labiatae</td><td>mint</td><td>7,175</td></tr><tr><td>7</td><td>Eudicot</td><td>Euphorbiaceae</td><td>spurge</td><td>5,735</td></tr><tr><td>8</td><td>Eudicot</td><td>Melastomataceae</td><td>melastome</td><td>5,005</td></tr><tr><td>9</td><td>Eudicot</td><td>Myrtaceae</td><td>myrtle</td><td>4,625</td></tr><tr><td>10</td><td>Eudicot</td><td>Apocynaceae</td><td>dogbane</td><td>4,555</td></tr><tr><td>11</td><td>Monocot</td><td>Cyperaceae</td><td>sedge</td><td>4,350</td></tr><tr><td>12</td><td>Eudicot</td><td>Malvaceae</td><td>mallow</td><td>4,225</td></tr><tr><td>13</td><td>Monocot</td><td>Araceae</td><td>arum</td><td>4,025</td></tr><tr><td>14</td><td>Eudicot</td><td>Ericaceae</td><td>heath</td><td>3,995</td></tr><tr><td>15</td><td>Eudicot</td><td>Gesneriaceae</td><td>gesneriad</td><td>3,870</td></tr><tr><td>16</td><td>Eudicot</td><td>Apiaceae or Umbelliferae</td><td>parsley</td><td>3,780</td></tr><tr><td>17</td><td>Eudicot</td><td>Brassicaceae or Cruciferae</td><td>cabbage</td><td>3,710</td></tr><tr><td>18</td><td>Magnoliid dicot</td><td>Piperaceae</td><td>pepper</td><td>3,600</td></tr><tr><td>19</td><td>Monocot</td><td>Bromeliaceae</td><td>bromeliad</td><td>3,540</td></tr><tr><td>20</td><td>Eudicot</td><td>Acanthaceae</td><td>acanthus</td><td>3,500</td></tr><tr><td>21</td><td>Eudicot</td><td>Rosaceae</td><td>rose</td><td>2,830</td></tr><tr><td>22</td><td>Eudicot</td><td>Boraginaceae</td><td>borage</td><td>2,740</td></tr><tr><td>23</td><td>Eudicot</td><td>Urticaceae</td><td>nettle</td><td>2,625</td></tr><tr><td>24</td><td>Eudicot</td><td>Ranunculaceae</td><td>buttercup</td><td>2,525</td></tr><tr><td>25</td><td>Magnoliid dicot</td><td>Lauraceae</td><td>laurel</td><td>2,500</td></tr></tbody></table>
Evolution
History of classification
From 1736, an illustration of Linnaean classification
The botanical term "angiosperm", from Greek words angeíon (ἀγγεῖον 'bottle, vessel') and spérma (σπέρμα 'seed'), was coined in the form "Angiospermae" by Paul Hermann in 1690, including only flowering plants whose seeds were enclosed in capsules. The term angiosperm fundamentally changed in meaning in 1827 with Robert Brown, when angiosperm came to mean a seed plant with enclosed ovules. In 1851, with Wilhelm Hofmeister's work on embryo-sacs, Angiosperm came to have its modern meaning of all the flowering plants including Dicotyledons and Monocotyledons. The APG system treats the flowering plants as an unranked clade without a formal Latin name (angiosperms). A formal classification was published alongside the 2009 revision in which the flowering plants rank as the subclass Magnoliidae. From 1998, the Angiosperm Phylogeny Group (APG) has reclassified the angiosperms, with updates in the APG II system in 2003, the APG III system in 2009, and the APG IV system in 2016.
Coevolution with pollinators
The evolutionary success and rapid diversification of angiosperms are largely attributed to their coevolutionary relationships with animal pollinators, particularly insects, birds, and bats. Unlike gymnosperms, which rely primarily on wind for pollen dispersal, flowering plants developed specialized traits—such as nectar production, vivid pigmentations, and complex volatile scents—to attract specific floral visitors. This mutualism often leads to pollination syndromes, where the morphology of a flower evolves to match the anatomy and sensory capabilities of its primary pollinator. For example, tube-shaped flowers often coevolve with long-tongued insects or hummingbirds, ensuring high pollination efficiency through physical "fit." This specialized relationship acts as a driver for reproductive isolation, as minor changes in floral structure can shift a plant's pollinator reliance, leading to the formation of new species and contributing to the immense taxonomic diversity of the clade.
External
In 2019, a molecular phylogeny of plants placed the flowering plants in their evolutionary context:
Internal
<table><thead><tr><th></th><th>Basal angiosperms Core angiosperms</th></tr></thead><tbody><tr><td> Angiosperms </td><td></td></tr><tr><td></td><td>Amborellales 1 sp. New Caledonia shrub</td></tr><tr><td></td><td>Nymphaeales c. 80 spp. water lilies & allies</td></tr><tr><td></td><td>Austrobaileyales c. 100 spp. woody plants</td></tr><tr><td></td><td>Magnoliids c. 10,000 spp. 3-part flowers, 1-pore pollen, usu. branch-veined leaves</td></tr><tr><td></td><td>Chloranthales 77 spp. Woody, apetalous</td></tr><tr><td></td><td>Monocots c. 70,000 spp. 3-part flowers, 1 cotyledon, 1-pore pollen, usu. parallel-veined leaves </td></tr><tr><td></td><td>Ceratophyllales c. 6 spp. aquatic plants</td></tr><tr><td></td><td>Eudicots c. 175,000 spp. 4- or 5-part flowers, 3-pore pollen, usu. branch-veined leaves</td></tr></tbody></table>
<table><thead><tr><th>Detailed cladogram of the 2016 Angiosperm Phylogeny Group (APG) IV classification.</th></tr></thead><tbody><tr><td>Angiosperms</td><td></td></tr><tr><td></td><td>Amborellales Melikyan, Bobrov & Zaytzeva 1999</td></tr><tr><td></td><td>Nymphaeales Salisbury ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Austrobaileyales Takhtajan ex Reveal 1992</td></tr><tr><td>Mesangiosperms</td><td></td></tr><tr><td></td><td>Chloranthales Mart. 1835</td></tr><tr><td>Magnoliids</td><td></td></tr><tr><td></td><td>Canellales Cronquist 1957</td></tr><tr><td></td><td>Piperales von Berchtold & Presl 1820</td></tr><tr><td></td><td>Magnoliales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Laurales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td>Monocots</td><td></td></tr><tr><td></td><td>Acorales Link 1835</td></tr><tr><td></td><td>Alismatales Brown ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Petrosaviales Takhtajan 1997</td></tr><tr><td></td><td>Dioscoreales Brown 1835</td></tr><tr><td></td><td>Pandanales Brown ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Liliales Perleb 1826</td></tr><tr><td></td><td>Asparagales Link 1829</td></tr><tr><td>Commelinids</td><td></td></tr><tr><td></td><td>Arecales Bromhead 1840</td></tr><tr><td></td><td>Poales Small 1903</td></tr><tr><td></td><td>Zingiberales Grisebach 1854</td></tr><tr><td></td><td>Commelinales de Mirbel ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Ceratophyllales Link 1829</td></tr><tr><td>Eudicots</td><td></td></tr><tr><td></td><td>Ranunculales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Proteales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Trochodendrales Takhtajan ex Cronquist 1981</td></tr><tr><td></td><td>Buxales Takhtajan ex Reveal 1996</td></tr><tr><td>Core eudicots</td><td></td></tr><tr><td></td><td>Gunnerales Takhtajan ex Reveal 1992</td></tr><tr><td></td><td>Dilleniales de Candolle ex von Berchtold & Presl 1820</td></tr><tr><td>Superrosids</td><td></td></tr><tr><td></td><td>Saxifragales von Berchtold & Presl 1820</td></tr><tr><td>Rosids</td><td></td></tr><tr><td></td><td>Vitales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td>Fabids</td><td></td></tr><tr><td></td><td>Zygophyllales Link 1829</td></tr><tr><td></td><td>Celastrales Link 1829</td></tr><tr><td></td><td>Oxalidales von Berchtold & Presl 1820</td></tr><tr><td></td><td>Malpighiales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Fabales Bromhead 1838</td></tr><tr><td></td><td>Rosales von Berchtold & Presl 1820</td></tr><tr><td></td><td>Cucurbitales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Fagales Engler 1892</td></tr><tr><td>(eurosids I)</td></tr><tr><td>Malvids</td><td></td></tr><tr><td></td><td>Geraniales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Myrtales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Crossosomatales Takhtajan ex Reveal 1993</td></tr><tr><td></td><td>Picramniales Doweld 2001</td></tr><tr><td></td><td>Sapindales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Huerteales Doweld 2001</td></tr><tr><td></td><td>Malvales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Brassicales Bromhead 1838</td></tr><tr><td>(eurosids II)</td></tr><tr><td>Superasterids</td><td></td></tr><tr><td></td><td>Berberidopsidales Doweld 2001</td></tr><tr><td></td><td>Santalales Brown ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Caryophyllales</td></tr><tr><td>Asterids</td><td></td></tr><tr><td></td><td>Cornales Link 1829</td></tr><tr><td></td><td>Ericales von Berchtold & Presl 1820</td></tr><tr><td>Lamiids</td><td></td></tr><tr><td></td><td>Icacinales Van Tieghem 1900</td></tr><tr><td></td><td>Metteniusales Takhtajan 1997</td></tr><tr><td></td><td>Garryales Mart. 1835</td></tr><tr><td></td><td>Gentianales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Solanales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Boraginales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td></td><td>Vahliales Doweld 2001</td></tr><tr><td></td><td>Lamiales Bromhead 1838</td></tr><tr><td>(euasterids I)</td></tr><tr><td>Campanulids</td><td></td></tr><tr><td></td><td>Aquifoliales Senft 1856</td></tr><tr><td></td><td>Escalloniales Mart. 1835</td></tr><tr><td></td><td>Asterales Link 1829</td></tr><tr><td></td><td>Bruniales Dumortier 1829</td></tr><tr><td></td><td>Apiales Nakai 1930</td></tr><tr><td></td><td>Paracryphiales Takhtajan ex Reveal 1992</td></tr><tr><td></td><td>Dipsacales de Jussieu ex von Berchtold & Presl 1820</td></tr><tr><td>(euasterids II)</td></tr></tbody></table>
In 2024, Alexandre R. Zuntini and colleagues constructed a tree of some 6,000 flowering plant genera, representing some 60% of the existing genera, on the basis of analysis of 353 nuclear genes in each specimen. Much of the existing phylogeny is confirmed; the rosid phylogeny is revised.
Tree of Angiosperm phylogeny 2024
Fossil history
Adaptive radiation in the Cretaceous created many flowering plants, such as Sagaria in the Ranunculaceae.
Fossilised spores suggest that land plants (embryophytes) have existed for at least 475 million years. However, angiosperms appear suddenly and in great diversity in the fossil record in the Early Cretaceous (~130 mya). Claimed records of flowering plants prior to this are not widely accepted, as all supposed pre-Cretaceous "flowers" can be explained through being misidentifications of other seed plants. Furthermore, almost all of these controversial fossils are described in papers co-authored by the researcher Xin Wang, such as the particularly debated Nanjinganthus. Molecular evidence suggests that the ancestors of angiosperms diverged from the gymnosperms during the late Devonian, about 365 million years ago. The origin time of the crown group of flowering plants remains contentious. By the Late Cretaceous, angiosperms appear to have dominated environments formerly occupied by ferns and gymnosperms. Large canopy-forming trees replaced conifers as the dominant trees close to the end of the Cretaceous, 66 million years ago. The radiation of herbaceous angiosperms occurred much later. Fossils from the Dakota Formation in Kansas suggest that Beetles had already developed a symbiotic relationship with flowering plants such as Archaeanthus by the late-Albian.
Reproduction
Flowers
Angiosperm flower showing reproductive parts and life cycle
The characteristic feature of angiosperms is the flower. Its function is to ensure fertilization of the ovule and development of fruit containing seeds. It may arise terminally on a shoot or from the axil of a leaf. The flower-bearing part of the plant is usually sharply distinguished from the leaf-bearing part, and forms a branch-system called an inflorescence.
Flowers produce two kinds of reproductive cells. Microspores, which divide to become pollen grains, are the male cells; they are borne in the stamens. The female cells, megaspores, divide to become the egg cell. They are contained in the ovule and enclosed in the carpel; one or more carpels form the pistil.
The flower may consist only of these parts, as in wind-pollinated plants like the willow, where each flower comprises only a few stamens or two carpels. In insect- or bird-pollinated plants, other structures protect the sporophylls and attract pollinators. The individual members of these surrounding structures are known as sepals and petals (or tepals in flowers such as Magnolia where sepals and petals are not distinguishable from each other). The outer series (calyx of sepals) is usually green and leaf-like, and functions to protect the rest of the flower, especially the bud. The inner series (corolla of petals) is, in general, white or brightly colored, is more delicate in structure, and attracts pollinators by colour, scent, and nectar.
Most flowers are hermaphroditic, producing both pollen and ovules in the same flower, but some use other devices to reduce self-fertilization. Heteromorphic flowers have carpels and stamens of differing lengths, so animal pollinators cannot easily transfer pollen between them. Homomorphic flowers may use a biochemical self-incompatibility to discriminate between self and non-self pollen grains. Dioecious plants such as holly have male and female flowers on separate plants. Monoecious plants have separate male and female flowers on the same plant; these are often wind-pollinated, as in maize, but include some insect-pollinated plants such as Cucurbita squashes.
Fertilisation and embryogenesis
Double fertilization requires two sperm cells to fertilise cells in the ovule. A pollen grain sticks to the stigma at the top of the pistil, germinates, and grows a long pollen tube. A haploid generative cell travels down the tube behind the tube nucleus. The generative cell divides by mitosis to produce two haploid (n) sperm cells. The pollen tube grows from the stigma, down the style and into the ovary. When it reaches the micropyle of the ovule, it digests its way into one of the synergids, releasing its contents including the sperm cells. The synergid that the cells were released into degenerates; one sperm makes its way to fertilise the egg cell, producing a diploid (2n) zygote. The second sperm cell fuses with both central cell nuclei, producing a triploid (3n) cell. The zygote develops into an embryo; the triploid cell develops into the endosperm, the embryo's food supply. The ovary develops into a fruit and each ovule into a seed.
Fruit and seed
The fruit of the horse chestnut tree, showing the large seed inside the fruit, which is dehiscing or splitting open.
As the embryo and endosperm develop, the wall of the embryo sac enlarges and combines with the nucellus and integument to form the seed coat. The ovary wall develops to form the fruit or pericarp, whose form is closely associated with type of seed dispersal system.
Other parts of the flower often contribute to forming the fruit. For example, in the apple, the hypanthium forms the edible flesh, surrounding the ovaries which form the tough cases around the seeds.
Apomixis, setting seed without fertilization, is found naturally in about 2.2% of angiosperm genera. Some angiosperms, including many citrus varieties, are able to produce fruits through a type of apomixis called nucellar embryony.
Sexual selection
Sexual selection is a mechanism of evolution in which members of one sex choose mates of the other sex (inter-sexual selection), and compete with members of the same sex for access to members of the opposite sex (intra-sexual selection). It is an accepted concept in zoology, but more controversial in botany. It could work through two principal mechanisms:
• Intra-sexual (male–male) competition: Competing pollen donors vie for ovule fertilization via traits such as pollen packaging, timing of release, and flower morphology. • Female or pistil-mediated mate choice: Post-pollination filters—such as pollen-recipient compatibility, pollen-tube growth rates, and selective seed abortion — enable differential siring success.
These two mechanisms are, in theory, the main driving forces of sexual selection in flowering plants and their potential relevance to botany is clear, but more complicated than in zoology. The complexity of applying the concept of sexual selection to plants arises from the facts that most plants are hermaphrodites and are non-sentient, meaning that the more obvious elements of female choice (e.g. aesthetic judgements on male secondary sexual characteristics) do not apply. The research challenge currently facing botanists is mainly empirical, namely how significant these processes have actually been in plant evolution.
Adaptive function of flowers
Charles Darwin in his 1878 book The Effects of Cross and Self-Fertilization in the Vegetable Kingdom in the initial paragraph 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." Flowers emerged in plant evolution as an adaptation for the promotion of cross-fertilisation (outcrossing), a process that allows the masking of deleterious mutations in the genome of progeny. The masking effect is known as genetic complementation. Meiosis in flowering plants provides a direct mechanism for repairing DNA through genetic recombination in reproductive tissues. Sexual reproduction appears to be required for maintaining long-term genomic integrity and only infrequent combinations of extrinsic and intrinsic factors permit shifts to asexuality. Thus the two fundamental aspects of sexual reproduction in flowering plants, cross-fertilization (outcrossing) and meiosis appear to be maintained respectively by the advantages of genetic complementation and recombinational repair.
Human uses
Practical uses
Harvesting rice in Arkansas, 2020
Food from plants: a dish of Dal tadka, Indian lentil soup
Agriculture is almost entirely dependent on angiosperms, which provide virtually all plant-based food and fodder for livestock. Much of this food derives from a small number of flowering plant families. For instance, half of the world's calorie intake is supplied by just three members of the grass family – wheat, rice and maize.
<table><thead><tr><th>Family</th><th>English</th><th>Example foods from that family</th></tr></thead><tbody><tr><td>Poaceae</td><td>Grasses, cereals</td><td>Most feedstocks, inc. rice, maize, wheat, barley, rye, oats, pearl millet, sugar cane, sorghum</td></tr><tr><td>Fabaceae</td><td>Legumes, pea family</td><td>Peas, beans, lentils; for animal feed, clover, alfalfa</td></tr><tr><td>Solanaceae</td><td>Nightshade family</td><td>Potatoes, tomatoes, peppers, aubergines</td></tr><tr><td>Cucurbitaceae</td><td>Gourd family</td><td>Squashes, cucumbers, pumpkins, melons</td></tr><tr><td>Brassicaceae</td><td>Cabbage family</td><td>Cabbage and its varieties, e.g. Brussels sprout, broccoli; mustard; oilseed rape</td></tr><tr><td>Apiaceae</td><td>Parsley family</td><td>Parsnip, carrot, parsley, coriander, fennel, cumin, caraway</td></tr><tr><td>Rutaceae</td><td>Rue family</td><td>Oranges, lemons, grapefruits</td></tr><tr><td>Rosaceae</td><td>Rose family</td><td>Apples, pears, cherries, apricots, plums, peaches</td></tr></tbody></table>
Flowering plants provide a diverse range of materials in the form of wood, paper, fibers such as cotton, flax, and hemp, medicines such as digoxin and opioids, and decorative and landscaping plants. Coffee and hot chocolate are beverages from flowering plants (in the Rubiaceae and Malvaceae respectively).
Cultural uses
Bird-and-flower painting: Kingfisher and iris kachō-e woodblock print by Ohara Koson (late 19th century)
Both real and fictitious plants play a wide variety of roles in literature and film. Flowers are the subjects of many poems by poets such as William Blake, Robert Frost, and Rabindranath Tagore. Bird-and-flower painting (Huaniaohua) is a kind of Chinese painting that celebrates the beauty of flowering plants. Flowers have been used in literature to convey meaning by authors including William Shakespeare. Flowers are used in a variety of art forms which arrange cut or living plants, such as bonsai, ikebana, and flower arranging. Ornamental plants have sometimes changed the course of history, as in tulipomania. Many countries and regions have floral emblems; a survey of 70 of these found that the most popular flowering plant family for such emblems is Orchidaceae at 15.7% (11 emblems), followed by Fabaceae at 10% (7 emblems), and Asparagaceae, Asteraceae, and Rosaceae all at 5.7% (4 emblems each).
Conservation
Viola calcarata, a species highly vulnerable to climate change.
Human impact on the environment has driven a range of species extinct and is threatening even more today. Multiple organizations such as IUCN and Royal Botanic Gardens, Kew suggest that around 40% of plant species are threatened with extinction. The majority are threatened by habitat loss, but activities such as logging of wild timber trees and collection of medicinal plants, or the introduction of non-native invasive species, also play a role.
Relatively few plant diversity assessments have considered climate change, yet it is starting to impact plants as well. About 3% of flowering plants are very likely to be driven extinct within a century at 2 °C (3.6 °F) of global warming, and 10% at 3.2 °C (5.8 °F). In worst-case scenarios, half of all tree species may be driven extinct by climate change over that timeframe.
Conservation in this context is the attempt to prevent extinction, whether in situ by protecting plants and their habitats in the wild, or ex situ in seed banks or as living plants. Some 3000 botanic gardens around the world maintain living plants, including over 40% of the species known to be threatened, as an "insurance policy against extinction in the wild." The United Nations' Global Strategy for Plant Conservation asserts that "without plants, there is no life". It aims to "halt the continuing loss of plant diversity" throughout the world.