List of the largest genera of flowering plants

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A buttercup flower, with three yellow petals out of five.
Agamospecies in the Ranunculus auricomus complex help to swell the number of species in the genus Ranunculus.

There are 57 genera of flowering plants estimated to contain at least 500 described species. The largest of these is currently the legume genus Astragalus (milk-vetches), 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.[1]

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.[2] 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.[2][3] 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.[2] 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.[2][3] 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.[1]

The introduction of infrageneric taxa (such as the subgenus, section and series) 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.[1]

Largest genera[edit]

A total of 57 genera of flowering plants contain at least 500 species, according to a 2004 analysis by the botanical taxonomist David Frodin.[1] The actual numbers of species are imprecisely known, as many of the genera have not been the subject of recent monographs.[3] For instance, estimates of the number of species in the orchid genus Pleurothallis range from 1,120 to 2,500. Genera from other groups of vascular plants, but which have similarly large numbers of species, include Selaginella, Asplenium and Cyathea.[1]

A legume with inflorescences of up to 40 elongated, ivory-coloured flowers, and pinnate leaves with many pairs of leaflets.
Astragalus is the largest flowering plant genus, with more than 3,200 species, including Astragalus agnicidus.
Five orchid flowers, each with spotted tepals and a pink labellum.
Bulbophyllum is the second largest flowering plant genus, with more than 2,000 species, including Bulbophyllum guttulatum.
A shrub with large, leathery, simple leaves, and bearing clusters of round, green fruit.
Psychotria is the third largest flowering plant genus, with more than 1,900 species, including Psychotria mariniana.
A group of unbranched herbs grow beside a plant label. The upper leaves and bracts grade from green to yellow.
Euphorbia is the fourth largest flowering plant genus, with more than 1,800 species, including Euphorbia amygdaloides.
Several small, grass-like plants with thin leaves, each with a stalk bearing a cluster of small round fruits.
Carex is the fifth largest flowering plant genus, with more than 1,700 species, including Carex pilulifera.
Genera of flowering plants with at least 500 species[1]
Rank Genus Species Family Species list
1 Astragalus !B9919074547361  3,270 Fabaceae / Leguminosae List of Astragalus species
2 Bulbophyllum !B9923832241913  2,032 Orchidaceae List of Bulbophyllum species
3 Psychotria !B9924239026593  1,951 Rubiaceae List of Psychotria species
4 Euphorbia !B9924846554288  1,836 Euphorbiaceae List of Euphorbia species
5 Carex !B9925072396990  1,795 Cyperaceae List of Carex species
6 Begonia !B9926975035762  1,484 Begoniaceae List of Begonia species
7 Dendrobium !B9927767043204  1,371 Orchidaceae List of Dendrobium species
8 Acacia !B9927899203718  c. 1,353 Fabaceae / Leguminosae List of Acacia species
9 Solanum !B9928691011697  c. 1,250 Solanaceae List of Solanum species
10 Senecio !B9928691011697  c. 1,250 Asteraceae / Compositae List of Senecio species
11 Croton !B9928909378643  1,223 Euphorbiaceae List of Croton species
12 Pleurothallis !B9929789160357  1,120+ Orchidaceae List of Pleurothallis species
13 Eugenia !B9929851856487  1,113 Myrtaceae
14 Piper !B9930387039540  1,055 Piperaceae
15 Ardisia !B9930472713553  1,046 Primulaceae
16 Syzygium !B9930520629313  1,041 Myrtaceae
17 Rhododendron !B9930912452206  c. 1,000 Ericaceae List of Rhododendron species
18 Miconia !B9930922447210  1,000 Melastomataceae
19 Peperomia !B9930922447210  1,000 Piperaceae List of Peperomia species
20 Salvia !B9931488150725  945 Lamiaceae / Labiatae List of Salvia species
21 Erica !B9932430676107  860 Ericaceae
22 Impatiens !B9932547636505  850 Balsaminaceae
23 Cyperus !B9932677892935  839 Cyperaceae
24 Phyllanthus !B9932749663578  833 Phyllanthaceae List of Phyllanthus species
25 Allium !B9932968118867  815 Amaryllidaceae List of Allium species
26 Epidendrum !B9933153882723  800 Orchidaceae List of Epidendrum species
27 Vernonia !B9933153882723  800–1,000 Asteraceae / Compositae
28 Lepanthes !B9933153882723  c. 800 Orchidaceae List of Lepanthes species
29 Anthurium !B9933292336791  789 Araceae List of Anthurium species
30 Diospyros !B9933575131986  767 Ebenaceae List of Diospyros species
31 Ficus !B9933799267934  750 Moraceae
32 Silene !B9934489196649  700 Caryophyllaceae
33 Indigofera !B9934474921129  700+ Fabaceae / Leguminosae
34 Oxalis !B9934489196649  700 Oxalidaceae
35 Crotalaria !B9934503492577  699 Fabaceae / Leguminosae
36 Centaurea !B9934560881544  695 Asteraceae / Compositae
37 Cassia !B9934604140443  692 Fabaceae / Leguminosae
38 Eucalyptus !B9934764376938  681 Myrtaceae List of Eucalyptus species
39 Oncidium !B9934779072018  680 Orchidaceae
40 Galium !B9935062461601  661 Rubiaceae List of Galium species
41 Cousinia !B9935153647643  655 Asteraceae / Compositae
42 Ipomoea !B9935230276371  650 Convolvulaceae
43 Dioscorea !B9935526941374  631 Dioscoreaceae
44 Cyrtandra !B9935670599072  622 Gesneriaceae
45 Helichrysum !B9936030703447  600 Asteraceae / Compositae
46 Ranunculus !B9936030703447  600 Ranunculaceae List of Ranunculus species
47 Habenaria !B9936030703447  600 Orchidaceae
48 Justicia !B9936030703447  600 Acanthaceae
49 Schefflera !B9936300990171  584 Araliaceae List of Schefflera species
50 Ixora !B9936702790944  561 Rubiaceae
51 Berberis !B9936792317057  556 Berberidaceae
52 Quercus !B9937252379787  531 Fagaceae List of Quercus species
53 Pandanus !B9937461711884  c. 520 Pandanaceae
54 Panicum !B9937833938989  500+ Poaceae / Gramineae List of Panicum species
55 Eria !B9937853919015  500 Orchidaceae
56 Polygala !B9937853919015  500 Polygalaceae
57 Potentilla !B9937853919015  500 Rosaceae List of Potentilla species


  1. ^ a b c d e f David G. Frodin (2004). "History and concepts of big plant genera". Taxon 53 (3): 753–776. doi:10.2307/4135449. JSTOR 4135449. 
  2. ^ a b c d Max Walters (1961). "The shaping of angiosperm taxonomy". New Phytologist 60 (1): 74–84. doi:10.1111/j.1469-8137.1961.tb06241.x. JSTOR 2429789. 
  3. ^ a b c David J. Mabberley (2008). "Introduction". Mabberley's Plant-book: a Portable Dictionary of Plants, their Classification and Uses (3rd ed.). Cambridge University Press. pp. vii–xv. ISBN 978-0-521-82071-4.