Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae () or Magnoliophyta. The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit.
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
Angiosperms are terrestrial vascular plants; like the gymnosperms, they have roots, stems, leaves, and seeds. They differ from other seed plants in several ways.
Feature Description ImageFlowers The reproductive organs of flowering plants, not found in any other seed plants. Reduced gametophytes, three cells in male, seven cells with eight nuclei in female (except for basal angiosperms) 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. Endosperm Endosperm forms after fertilization but before the zygote divides. It provides food for the developing embryo, the cotyledons, and sometimes the seedling. Closed carpel enclosing the ovules. Once the ovules are fertilised, the carpels, often with surrounding tissues, develop into fruits. Gymnosperms have unenclosed seeds. Xylem made of vessel elements Open vessel elements are stacked end to end to form continuous tubes, whereas gymnosperm xylem is made of tapered tracheids connected by small pits.
Diversity
Ecological diversity
The largest angiosperms are Eucalyptus gum trees of Australia, and Shorea faguetiana, dipterocarp rainforest trees of Southeast Asia, both of which can reach almost in height. The smallest are Wolffia duckweeds which float on freshwater, each plant less than across.
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.
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.
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.
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:
+ The 25 largest angiosperm families Group Family English name No. of spp. 1 Eudicot Asteraceae or Compositae daisy 22,750 2 Monocot Orchidaceae orchid 21,950 3 Eudicot Fabaceae or Leguminosae pea, legume 19,400 4 Eudicot Rubiaceae madder 13,150 5 Monocot Poaceae or Gramineae grass 10,035 6 Eudicot Lamiaceae or Labiatae mint 7,175 7 Eudicot Euphorbiaceae spurge 5,735 8 Eudicot Melastomataceae melastome 5,005 9 Eudicot Myrtaceae myrtle 4,625 10 Eudicot Apocynaceae dogbane 4,555 11 Monocot Cyperaceae sedge 4,350 12 Eudicot Malvaceae mallow 4,225 13 Monocot Araceae arum 4,025 14 Eudicot Ericaceae heath 3,995 15 Eudicot Gesneriaceae gesneriad 3,870 16 Eudicot Apiaceae or Umbelliferae parsley 3,780 17 Eudicot Brassicaceae or Cruciferae cabbage 3,710 18 Magnoliid dicot Piperaceae pepper 3,600 19 Monocot Bromeliaceae bromeliad 3,540 20 Eudicot Acanthaceae acanthus 3,500 21 Eudicot Rosaceae rose 2,830 22 Eudicot Boraginaceae borage 2,740 23 Eudicot Urticaceae nettle 2,625 24 Eudicot Ranunculaceae buttercup 2,525 25 Magnoliid dicot Lauraceae laurel 2,500
Evolution
History of classification
The botanical term "angiosperm", from Greek words ( 'bottle, vessel') and ( '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.
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.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.
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.
Phylogeny
External
In 2019, a molecular phylogeny of plants placed the flowering plants in their evolutionary context:
Internal
The main groups of living angiosperms are:
Detailed cladogram of the 2016 Angiosperm Phylogeny Group (APG) IV classification.
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.
Fossil history
Fossilised spores suggest that land plants (embryophytes) have existed for at least 475 million years. However, angiosperms appeared suddenly and rapidly diversified during the Early Cretaceous (beginning ~130 mya), much later than other major plant groups. 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 to early Carboniferous, around 371-338 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
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.