List of the largest genera of flowering plants

From Wikipedia, the free encyclopedia

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 over 56 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]

According to a 2004 analysis by the botanical taxonomist David G. Frodin, a total of 57 genera of flowering plants contain at least 500 species.[1] It is clear that there are other genera with over 500 species, as the work of taxonomists continues. 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 3,270 Fabaceae List of Astragalus species
2 Bulbophyllum 2,032 Orchidaceae List of Bulbophyllum species
3 Psychotria 1,951 Rubiaceae List of Psychotria species
4 Euphorbia 1,836 Euphorbiaceae List of Euphorbia species
5 Carex 1,795 Cyperaceae List of Carex species
6 Begonia 1,484 Begoniaceae List of Begonia species
7 Dendrobium 1,371 Orchidaceae List of Dendrobium species
8 Acacia c. 1,353 Fabaceae List of Acacia species
9 Solanum c. 1,250 Solanaceae List of Solanum species
10 Senecio c. 1,250 Asteraceae List of Senecio species
11 Croton 1,223 Euphorbiaceae List of Croton species
12 Pleurothallis 1,120+ Orchidaceae List of Pleurothallis species
13 Eugenia 1,113 Myrtaceae List of Eugenia species
14 Piper 1,055 Piperaceae List of Piper species
15 Ardisia 1,046 Primulaceae List of Ardisia species
16 Syzygium 1,041 Myrtaceae List of Syzygium species
17 Rhododendron c. 1,000 Ericaceae List of Rhododendron species
18 Miconia 1,000 Melastomataceae List of Miconia species
19 Peperomia 1,000 Piperaceae List of Peperomia species
20 Salvia 945 Lamiaceae List of Salvia species
21 Erica 860 Ericaceae List of Erica species
22 Impatiens 850 Balsaminaceae List of Impatiens species
23 Cyperus 839 Cyperaceae List of Cyperus species
24 Phyllanthus 833 Phyllanthaceae List of Phyllanthus species
25 Allium 815 Amaryllidaceae List of Allium species
26 Epidendrum 800 Orchidaceae List of Epidendrum species
27 Vernonia 800–1,000 Asteraceae List of Vernonia species
28 Lepanthes c. 800 Orchidaceae List of Lepanthes species
29 Anthurium 789 Araceae List of Anthurium species
30 Diospyros 767 Ebenaceae List of Diospyros species
31 Ficus 750 Moraceae List of Ficus species
32 Indigofera 700+ Fabaceae
33 Justicia c. 700[4] Acanthaceae List of Justicia species
34 Silene 700–900 Caryophyllaceae List of Silene species
35 Oxalis 700 Oxalidaceae List of Oxalis species
36 Crotalaria 699 Fabaceae List of Crotalaria species
37 Centaurea 695 Asteraceae List of Centaurea species
38 Cassia 692 Fabaceae
39 Eucalyptus 681 Myrtaceae List of Eucalyptus species
40 Oncidium 680 Orchidaceae
41 Galium 661 Rubiaceae List of Galium species
42 Cousinia 655 Asteraceae List of Cousinia species
43 Ipomoea 650 Convolvulaceae List of Ipomoea species
44 Dioscorea 631 Dioscoreaceae
45 Cyrtandra 622 Gesneriaceae List of Cyrtandra species
46 Helichrysum 600 Asteraceae List of Helichrysum species
47 Ranunculus 600 Ranunculaceae List of Ranunculus species
48 Habenaria 600 Orchidaceae List of Habenaria species
49 Schefflera 584 Araliaceae List of Schefflera species
50 Ixora 561 Rubiaceae List of Ixora species
51 Berberis 556 Berberidaceae List of Berberis species
52 Quercus 531 Fagaceae List of Quercus species
53 Pandanus c. 520 Pandanaceae List of Pandanus species
54 Panicum 500+ Poaceae List of Panicum species
55 Polygala 500 Polygalaceae List of Polygala species
56 Potentilla 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.
  4. ^ Daniel, Thomas F. (2011). "Justicia (Acanthaceae) in Texas". Journal of the Botanical Research Institute of Texas. 5 (2): 595–618. JSTOR 41972309.