Phyllanthus is the largest genus in the plant family Phyllanthaceae. Estimates of the number of species in this genus vary widely, from 750David J. Mabberley. 2008. Mabberley's Plant-Book. third edition (2008). Cambridge University Press. to 1200. Phyllanthus has a remarkable diversity of growth forms including annual and perennial herbs, shrubs, climbers, floating aquatics, and pachycaulous succulents. Some have flattened leaflike stems called cladodes. It has a wide variety of floral morphologies and chromosome numbers and has one of the widest range of pollen types of any seed plant genus.
Despite their variety, almost all Phyllanthus species express a specific type of growth called "phyllanthoid branching" in which the vertical stems bear deciduous, floriferous (flower-bearing), plagiotropic (horizontal or oblique) stems. The leaves on the main (vertical) axes are reduced to scales called "cataphylls", while leaves on the other axes develop normally. Phyllanthus is distributed in all tropical and subtropical regions on Earth.
Phyllanthus was first described by Carl Linnaeus in 1753;Linnaeus, C. (1753) Species Plantarum 2: 981. the type species has subsequently been designated as Phyllanthus niruri.
Taxonomy The circumscription of this genus has been a cause of much confusion and disagreement. Molecular phylogenetic studies have shown that Phyllanthus is paraphyletic over Reverchonia, Glochidion, Sauropus, and Breynia. A 2006 revision of the family Phyllanthaceae has subsumed all four of these genera into Phyllanthus. This enlarged version of Phyllanthus might eventually be divided into smaller genera,Kanchana Pruesapan, Ian R.H. Telford, Jeremy J. Bruhl, Stefano G.A. Draisma, and Peter C. Van Welzen. 2008. "Delimitation of Sauropus (Phyllanthaceae) Based on Plastid matK and Nuclear Ribosomal ITS DNA Sequence Data." Annals of Botany 102(6):1007-1018 including 32 Chinese (and northern Indochinese) species. A complete overhaul of the genus, including a new classification was underway in the 2020s, following an in-depth molecular treatment of major groups included. Proposed new genera are Breynia, Cathetus, Cicca, Dendrophyllanthus, Emblica, Flueggea, Glochidion, Heterosavia, Kirganelia, Lingelsheimia, Lysiandra, Margaritaria, Moeroris, Nellica, Nymphanthus, Phyllanthus (s.s.), Plagiocladus and Synostemon.
Species
Selected species
Phyllanthus abnormis Baill. – Drummond's leafflower Phyllanthus acidus (L.) Skeels – Otaheite gooseberry Phyllanthus acuminatus Vahl – Jamaican gooseberry tree Phyllanthus amarus Schumacher Phyllanthus anamalayanus (Gamble) G.L.Webster Phyllanthus angustifolius (Sw.) Sw. Phyllanthus arbuscula (Sw.) J.F.Gmel. Phyllanthus axillaris (Sw.) Müll.Arg. Phyllanthus brasiliensis (Aubl.) Poir. Phyllanthus caesiifolius Petra Hoffm. & Cheek Phyllanthus caroliniensis Walt. – native to the Americas Phyllanthus cauliflorus (Sw.) Griseb. Phyllanthus cladanthus Müll.Arg. Phyllanthus cochinchinensis (Lour.) Spreng. Phyllanthus coluteoides Baill. ex Müll.Arg. Phyllanthus cuneifolius (Britt.) Croizat Phyllanthus debilis Klein ex Willd. Phyllanthus distichus Hook. & Arn. Phyllanthus emblica L. – Indian gooseberry, also known as amla or amalaki. Phyllanthus engleri Pax Phyllanthus epiphyllanthus L. Phyllanthus ericoides Torr. Phyllanthus eximius G.L.Webster & Proctor Phyllanthus fadyenii Urb. Phyllanthus fluitans Benth. ex Müll.Arg. – red root floater, sometimes sold in aquarium shops Phyllanthus fraternus G.L.Webster Phyllanthus gentryi Webster Phyllanthus grandifolius L. Phyllanthus gunnii Hook.f. Phyllanthus hakgalensis Phyllanthus hirtellus F.Muell. ex Mull.Arg. Phyllanthus juglandifolius Willd. Phyllanthus lacunarius F.Muell. Phyllanthus latifolius (L.) Sw. Phyllanthus liebmannianus Muell.Arg. Phyllanthus maderaspatensis L. Phyllanthus microcladus Muell.Arg. Phyllanthus millei Standl. Phyllanthus mirabilis Müll.Arg. – one of the four succulent species of this genus Phyllanthus montanus (Sw.) Sw. Phyllanthus myrtifolius (Wight.) Muell.Arg. Phyllanthus muellerianus (Kuntze) Exell Phyllanthus niruri L. – Chanca piedra (Also includes P. amarus and P. debilis) Phyllanthus nyale Petra Hoffm. & Cheek Phyllanthus parvifolius Buch.-Ham. ex D.Don Phyllanthus pavonianus Baill. Phyllanthus pentaphyllus C.Wright ex Griseb. Phyllanthus phialanthoides Falcón & J.L.Gómez"Phyllanthus phialanthoides (Phyllanthaceae), a new species from northeastern Cuba" (JSTOR) Phyllanthus polygonoides Nutt. ex Spreng. – Smartweed leafflower Phyllanthus polyspermus Shumach. & Thonn. – often misidentified as P. reticulatus Phyllanthus profusus N.E.Br. Phyllanthus pulcher Wallich ex Muell.Arg. Phyllanthus reticulatus Poir. – Asian sp. similar in appearance to P. polyspermusLuo, S.X., H.-J. Esser, D. Zhang, and S. S. Renner. 2011. Nuclear ITS sequences help disentangle Phyllanthus reticulatus (Phyllanthaceae), an Asian species not occurring in Africa, but introduced to Jamaica. Systematic Botany 36(1): 99-104. Phyllanthus revaughanii Coode Phyllanthus rufuschaneyi Welzen, R.W.Bouman & Ent Phyllanthus saffordii Merr. Phyllanthus salviifolius Kunth Phyllanthus sepialis Müll.Arg. Phyllanthus societatis Müll.Arg. Phyllanthus sponiifolius Müll.Arg. Phyllanthus stipulatus (Raf.) G.L. Webster Phyllanthus taxodiifolius Beille Phyllanthus tenellus Roxb. Phyllanthus urinaria L. – chamberbitter Phyllanthus virgatus G.Forst. Phyllanthus warnockii G.L.Webster Phyllanthus watsonii Airy Shaw Phyllanthus welwitschianus Müll.Arg.
Fossil record Two fossil seeds of a Phyllanthus species have been extracted from borehole samples of the Middle Miocene fresh water deposits in Nowy Sacz Basin, West Carpathians, Poland. The seeds are similar to seeds of the fossil species †Phyllanthus triquetra and †Phyllanthus compassica from the Oligocene and Miocene of West Siberia. Phyllanthus fossils are known from several Miocene and Pliocene sites in Poland.Macroscopic plant remains from the freshwater Miocene of the Nowy Sącz Basin (West Carpathians, Poland) by Łańcucka-Środoniowa M, Acta Palaeobotanica 1979 20 (1): 3-117.
Pollination biology
Phyllanthus are of note in the fields of pollination biology and coevolution because some but not all species in the genus have a specialized mutualism with moths in the genus Epicephala (leafflower moths), in which the moths actively pollinate the flowers. While ensuring that the tree may produce viable seeds, the moths also lay eggs in the flowers' ovaries where their larvae consume a subset of the developing seeds as nourishment.Kawakita, A.; Kato, M. 2004. "Evolution of obligate pollination mutualism in New Caledonian Phyllanthus (Euphorbiaceae)." American Journal of Botany 91: 410–415.Kawakita, A.; Kato, M. 2009. "Repeated independent evolution of obligate pollination mutualism in the Phyllantheae-Epicephala association." Proceedings of the Royal Society B. 276: 417–426. Other species of Epicephala are pollinators of certain species of plants in the genera GlochidionHembry, D. H.; Okamoto, T.; Gillespie, R. G. (2012) Repeated colonization of remote islands by specialized mutualists. Biology Letters. 8: 258–261.Luo, S.-X.; Yao, G.; Wang, Z.; Zhang, D.; Hembry, D. H. (2017) "A novel, enigmatic basal leafflower moth lineage pollinating a derived leafflower host illustrates the dynamics of host shifts, partner replacement, and apparent co-adaptation in intimate mutualisms." The American Naturalist. 189: 422–435 and Breynia,Kawakita, A.; Kato, M. 2004. Obligate pollination mutualism in Breynia (Phyllanthaceae): further documentation of pollination mutualism involving Epicephala moths (Gracillariidae). American Journal of Botany. 91: 1319–1325.Zhang, J.; Wang, S.; Li, H.; Hu, B.; Yang, X.; Wang, Z. 2012. "Diffuse coevolution between two Epicephala species (Gracillariidae) and two Breynia species (Phyllanthaceae). PLOS ONE. 7: e41657. both of which are phylogenetically nested within Phyllanthus.Kathriarachchi, H.; Samuel, R.; Hoffmann, P.; Mlinarec, J.; Wurdack, K. J.; Ralimanana, H.; Stuessy, T. F.; Chase, M. W. 2006. "Phylogenetics of tribe Phyllantheae (Phyllanthaceae: Euphorbiaceae sensu lato) based on nrITS and plastid matK DNA sequence data." American Journal of Botany. 93: 637–655.
Research and traditional medicine
Particularly for its content of tannins, P. emblica fruit has a history of use in traditional medicine and is under study for its potential biological properties. Leaves, roots, stem, bark and berries of this genus contain lignans and other phytochemicals.
References