List of the largest genera of flowering plants


There are over 80 genera of flowering plants estimated to contain at least 500 described species. The largest of these is currently the legume genus Astragalus, with over 3,000 species.
The sizes of plant genera vary widely from those containing a single species to genera containing thousands of species, and this disparity became clear early in the history of plant classification. The largest genus in Carl Linnaeus' seminal Species Plantarum was Euphorbia, with 56 species; Linnaeus believed that no genus should contain more than 100 species.
Part of the disparity in genus sizes is attributable to historical factors. According to a hypothesis published by Max Walters in 1961, the size of plant genera is related to the age, not of the taxon itself, but of the concept of the taxon in the minds of taxonomists. Plants which grew in Europe, where most of the early taxonomy was based, were therefore divided into relatively small genera, while those from the tropics were grouped into much larger and more heterogeneous genera. Likewise, plants which shared common medicinal properties, such as the many species of Euphorbia, were united into a single genus, while plants of diverse uses, such as the grasses, were split into many genera. Where there were many classical names for groups of plants, such as in Apiaceae / Umbelliferae or Brassicaceae / Cruciferae, small genera were defined, whereas groups not subdivided by classical authors remained as larger genera, such as Carex. A number of biological factors also influence the number of species. For instance, the occurrence of apomixis allows the recognition of large numbers of agamospecies, and such taxa have helped to bolster genera such as Ranunculus and Potentilla.
The introduction of infrageneric taxa in the 19th century by botanists including Augustin Pyrame de Candolle allowed the retention of large genera that would otherwise have become unwieldy. E. J. H. Corner believed that studying large genera might enable greater insights into evolutionary biology, and he concentrated his efforts on large tropical genera such as Ficus.

Largest genera

, there are a total of 86 genera of flowering plants with at least 500 species. It is clear that there are other genera with over 500 species, as the work of taxonomists continues. Currently, the number of species included in many genera is very different, so their ranking is subject to changes. The actual number of species is also imprecisely known because of different approaches of taxonomists, and many of the genera have not been the subject of recent monographs. For instance, estimates of the number of species in the orchid genus Pleurothallis range from 1,120 to 2,500. Genera from some other groups of vascular plants, which have similarly large numbers of species, include Selaginella, Asplenium and Cyathea.
File:Astragalusagnicidus.jpg|thumb|Astragalus is the largest flowering plant genus, with more than 3,200 species, including Astragalus agnicidus.|alt=A legume with inflorescences of up to 40 elongated, ivory-coloured flowers, and pinnate leaves with many pairs of leaflets.
File:Bulbophyllumguttulatum24.JPG|thumb|Bulbophyllum is the second largest flowering plant genus, with more than 2,000 species, including Bulbophyllum guttulatum.|alt=Five orchid flowers, each with spotted tepals and a pink labellum.
File:Starr 020925-0087 Psychotria mariniana.jpg|thumb|Psychotria is the third largest flowering plant genus, with more than 1,900 species, including Psychotria mariniana.|alt=A shrub with large, leathery, simple leaves, and bearing clusters of round, green fruit.
File:Euphorbia amygdaloides - Berlin Botanical Garden - IMG 8500.JPG|thumb|Euphorbia is the fourth largest flowering plant genus, with more than 1,800 species, including Euphorbia amygdaloides.|alt=A group of unbranched herbs grow beside a plant label. The upper leaves and bracts grade from green to yellow.
File:Carex pilulifera habitus.jpeg|thumb|Carex is the fifth largest flowering plant genus, with more than 1,700 species, including Carex pilulifera.|alt=Several small, grass-like plants with thin leaves, each with a stalk bearing a cluster of small round fruits.
RankGenusSpeciesFamilySpecies list
1Astragalus 3,239FabaceaeAstragalus species|List of Astragalus species]
2Taraxacum 2,387AsteraceaeList of [Taraxacum species|List of Taraxacum species]
3Hieracium 2,349AsteraceaeList of [Hieracium species|List of Hieracium species]
4Carex 2,328CyperaceaeList of [Carex species|List of Carex species]
5Bulbophyllum 2,190OrchidaceaeList of [Bulbophyllum species|List of Bulbophyllum species]
6Piper 2,169PiperaceaePiper species|List of Piper species]
7Euphorbia 2,157EuphorbiaceaeList of [Euphorbia species|List of Euphorbia species]
8Begonia 2,144BegoniaceaeList of [Begonia species|List of Begonia species]
9Miconia 1,939MelastomataceaeList of [Miconia species|List of Miconia species]
10Epidendrum 1,872OrchidaceaeList of [Epidendrum species|List of Epidendrum species]
11Rubus 1,732RosaceaeList of [Rubus species|List of Rubus species]
12Senecio 1,681AsteraceaeList of [Senecio species|List of Senecio species]
13Psychotria 1,650RubiaceaeList of [Psychotria species|List of Psychotria species]
14Dendrobium 1,647OrchidaceaeList of [Dendrobium species|List of Dendrobium species]
15Ranunculus 1,616RanunculaceaeList of [Ranunculus species|List of Ranunculus species]
16Peperomia 1,384PiperaceaeList of [Peperomia species|List of Peperomia species]
17Anthurium 1,346AraceaeList of [Anthurium species|List of Anthurium species]
18Stelis 1,338OrchidaceaeList of [Stelis species|List of Stelis species]
19Eugenia 1,284MyrtaceaeList of [Eugenia species|List of Eugenia species]
20Solanum 1,238SolanaceaeList of [Solanum species|List of Solanum species]
21Syzygium 1,236MyrtaceaeList of [Syzygium species|List of Syzygium species]
22Acacia 1,234FabaceaeList of [Acacia species|List of Acacia species]
23Rhododendron 1,195EricaceaeList of [Rhododendron species|List of Rhododendron species]
24Lepanthes 1,189OrchidaceaeList of [Lepanthes species|List of Lepanthes species]
25Croton 1,178EuphorbiaceaeCroton species|List of Croton species]
26Salvia 1,049LamiaceaeList of [Salvia species|List of Salvia species]
27Phyllanthus 1,025PhyllanthaceaeList of [Phyllanthus species|List of Phyllanthus species]
28Impatiens 1,002BalsaminaceaeList of [Impatiens species|List of Impatiens species]
29Justicia 983AcanthaceaeJusticia species|List of Justicia species]
30Allium 970AmaryllidaceaeList of [Allium species|List of Allium species]
31Cyperus 961CyperaceaeList of [Cyperus species|List of Cyperus species]
32Habenaria 908OrchidaceaeList of [Habenaria species|List of Habenaria species]
33Ficus 876MoraceaeList of [Ficus species|List of Ficus species]
34Eucalyptus 865MyrtaceaeList of [Eucalyptus species|List of Eucalyptus species]
35Erica 853EricaceaeErica species|List of Erica species]
36Myrcia 820MyrtaceaeList of [Myrcia species|List of Myrcia species]
37Centaurea 793AsteraceaeList of [Centaurea species|List of Centaurea species]
38Diospyros 787EbenaceaeList of [Diospyros species|List of Diospyros species]
39Indigofera 787FabaceaeList of [Indigofera species|List of Indigofera species]
40Vaccinium 785EricaceaeList of [Vaccinium species|List of Vaccinium species]
41Crotalaria 760FabaceaeList of [Crotalaria species|List of Crotalaria species]
42Cyrtandra 749GesneriaceaeCyrtandra species|List of Cyrtandra species]
43Alchemilla 734RosaceaeList of [Alchemilla species|List of Alchemilla species]
44Viola 727ViolaceaeViola species|List of Viola species]
45Verbascum 724ScrophulariaceaeList of [Verbascum species|List of Verbascum species]
46Vernonia 723AsteraceaeList of [Vernonia species|List of Vernonia species]
47Ardisia 721PrimulaceaeList of [Ardisia species|List of Ardisia species]
48Pedicularis 711OrobanchaceaeList of [Pedicularis species|List of Pedicularis species]
49Cousinia 709AsteraceaeList of [Cousinia species|List of Cousinia species]
50Mimosa 689FabaceaeList of [Mimosa species|List of Mimosa species]
51Palicourea 689Rubiaceae
52Festuca 686PoaceaeList of [Festuca species|List of Festuca species]
53Tillandsia 678BromeliaceaeList of [Tillandsia species|List of Tillandsia species]
54Galium 678RubiaceaeList of [Galium species|List of Galium species]
55Polygala 673PolygalaceaeList of [Polygala species|List of Polygala species]
56Maxillaria 658OrchidaceaeList of [Maxillaria species|List of Maxillaria species]
57Masdevallia 656OrchidaceaeList of [Masdevallia species|List of Masdevallia species]
58Oxytropis 654FabaceaeList of [Oxytropis species|List of Oxytropis species]
59Elatostema 652Urticaceae
60Lupinus 650FabaceaeList of [Lupinus species|List of Lupinus species]
61Dioscorea 649Dioscoreaceae
62Salix 629SalicaceaeList of [Salix species|List of Salix species]
63Berberis 628Berberidaceae-
64Quercus 627FagaceaeList of [Quercus species|List of Quercus species]
65Aloe 623AsphodelaceaeList of [Aloe species|List of Aloe species]
66Ipomoea 621ConvolvulaceaeList of [Ipomoea species|List of Ipomoea species]
67Poa 617PoaceaeList of [Poa species|List of Poa species]
68Pilea 613UrticaceaeList of [Pilea species|List of Pilea species]
69Pandanus 605PandanaceaeList of [Pandanus species|List of Pandanus species]
70Ilex 596AquifoliaceaeList of [Ilex species|List of Ilex species]
71Coelogyne 595OrchidaceaeList of [Coelogyne species|List of Coelogyne species]
72Helichrysum 580AsteraceaeList of [Helichrysum species|List of Helichrysum species]
73Philodendron 569AraceaeList of [Philodendron species|List of Philodendron species]
74Ixora 566RubiaceaeList of [Ixora species|List of Ixora species]
75Passiflora 561PassifloraceaeList of [Passiflora species|List of Passiflora species]
76Saxifraga 561SaxifragaceaeList of [Saxifraga species|List of Saxifraga species]
77Oxalis 557OxalidaceaeList of [Oxalis species|List of Oxalis species]
78Pleurothallis 556OrchidaceaeList of [Pleurothallis species|List of Pleurothallis species]
79Primula 553PrimulaceaeList of [Primula species|List of Primula species]
80Ocotea 545LauraceaeList of [Ocotea species|List of Ocotea species]
81Corydalis 528PapaveraceaeList of [Corydalis species|List of Corydalis species]
82Aristolochia 524AristolochiaceaeList of [Aristolochia species|List of Aristolochia species]
83 Artemisia 523AsteraceaeList of Artemisia species
84Hypericum 517HypericaceaeList of [Hypericum species|List of Hypericum species]
85Potentilla 505RosaceaeList of [Potentilla species|List of Potentilla species]
86Delphinium 503RanunculaceaeList of [Delphinium species|List of Delphinium species]