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 and σπέρμα, 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, 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. 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	Image
Flowers	The reproductive organs of flowering plants, not found in any other seed plants.	File:Daffodil flower in section, labelled.svg\|thumb\|none\|A Narcissus flower in section. Petals and sepals are replaced here by a fused tube, the corona, and tepals.
Reduced gametophytes, three cells in male, seven cells with eight nuclei in female	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.	File:Angiosperm embryo sac with female gametophyte.JPG\|thumb\|none\|Embryo sac is a reduced female gametophyte.
Endosperm	Endosperm forms after fertilization but before the zygote divides. It provides food for the developing embryo, the cotyledons, and sometimes the seedling.	File:Angiosperm embryo sac with female gametophyte.JPG\|thumb\|none\|Embryo sac is a reduced female gametophyte.
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 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, 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, monocot, and magnoliid 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:

	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 angeíon and spérma, 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. 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 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.

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 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.