Phyllanthaceae comprises about 2000 species. Depending on the author, these are grouped into 54 to 60 genera. Some of the genera are poorly defined, and the number of genera in the family is likely to change as the classification is further refined. The genus Phyllanthus, one of the largest genera of flowering plants, with over 1200 species, has more than half of the species in the family.
Some of the genera have recently been sunk into others, while other genera have recently been divided. The largest genera and the approximate number of species in each are: Phyllanthus (1270), Cleistanthus (140), Antidesma (100), Aporosa (90), Uapaca (60), Baccaurea (50), and Bridelia (50).
Since Phyllanthaceae was revised in 2006, one paper has removed Heterosavia from Savia. Another has separated Notoleptopus from Leptopus, and segregated Pseudophyllanthus and Phyllanthopsis from Andrachne. Also, Oreoporanthera has been subsumed into Poranthera, while Zimmermannia and Zimmermanniopsis have been sunk into Meineckia. The large genus Cleistanthus is known to be polyphyletic, but further studies will be needed before it can be revised.
The description here is from Hoffmann, except for a few additions from Webster and Hutchinson  where cited. Phyllanthaceae is an unusually diverse family for its moderate size. It can be recognized only by a combination of characters because there are a few exceptions to almost everything that is generally true of the family. It is most notable for having two ovules in each locule of the ovary, a trait that clearly distinguishes it from Euphorbiaceae.
The Phyllanthaceae are nearly all trees, shrubs, or herbs. A few are climbers, or succulents, and one species, Phyllanthus fluitans, is aquatic. Unlike many of the Euphorbiaceae, none has latex, and only a very few produce a resinous exudate. Any hairs, if present, are almost always simple. Rarely are they branched or scale-like. Thorns and other armament are rare.
Stipules are produced with each leaf, but in some, these fall before the leaf is fully mature. Leaves are present, except for a few species of Phyllanthus that have flattened, leaflike stems called cladodes that bear flowers along their edges. The leaves are compound in Bischofia, but otherwise simple and usually alternate. Rarely are they opposite, in fascicles, or in whorls around the stem. The leaf margin is almost always entire, rarely toothed. A petiole is nearly always present, often with a pulvinus at its base.
The inflorescences are usually in the axils of leaves, rarely below the leaves or at the ends of stems. In Uapaca, the flowers are in a pseudanthium, a tight bundle of flowers that resembles a single flower.
Except for four species of Aporosa, the flowers are unisexual, the plants being either monoecious or dioecious. The flowers are actinomorphic in form. Detailed illustrations have been published for some of these.
The sepals are three to eight in number, usually free from each other. Petals may be absent or present. If present, there are usually four to six, and their color is yellow to green, or rarely, pink or maroon.
The ovary is superior. The number of locules in the ovary is highly variable, usually from two to five, but sometimes as many as fifteen. The placentation is apical, with a pair of ovules hanging by their funicles from the top of each locule. Often, only one of the ovules will develop into a seed. A single, massive obturator may cover the micropyles of both ovules, or each ovule may have its own thin obturator. The megagametophyte is of the Polygonum type. The style is usually 2-lobed or bifid, sometimes entire, or rarely multifid.
Martynov's name was rarely used in the 180 years after he published it. During that time, the plants that are now in Phyllanthaceae were placed in the large and heterogeneous family Euphorbiaceae. The monophyly of Euphorbiaceae had long been held in doubt by some, but the first strong evidence of its polyphyly came in 1993 with the first maximum parsimony analysis of DNA sequences of the gene rbcL from a large number of seed plants. Since the 1993 study, all subsequent phylogenetic analyses have shown that the old concept of Euphorbiaceae consisted of several lineages that did not together form a clade in the order Malpighiales. Euphorbiaceae is now defined as a much smaller family than it had been in the twentieth century. Pandaceae, Phyllanthaceae, Picrodendraceae, Putranjivaceae, Peraceae, and Centroplacaceae have been removed from it.
The obsolete, older concept of Euphorbiaceae, known as Euphorbiaceae sensu lato, is sometimes still used for continuity and convenience. It was the subject of a book and two papers which stood as the standard works on Phyllanthaceae until that family was revised by Hoffmann and co-authors in 2006.
In the past, the genera Centroplacus, Paradrypetes, and Phyllanoa had been placed in Phyllanthaceae, but these are now excluded from the family. Centroplacus is now in the family Centroplacaceae. Paradrypetes is in Rhizophoraceae. Phyllanoa is known only from a single specimen. In 1996, this was examined and found to be a species of Rinorea (Violaceae).
The family Phyllanthaceae is divided into two subfamilies: Antidesmatoideae and Phyllanthoideae. Antidesmatoideae is divided into six tribes and Phyllanthoideae is divided into four. The tribe Antidesmateae of Antidesmatoideae, and the tribes Bridelieae and Wielandieae of Phyllanthoideae are further divided into subtribes. The following classification table is from the 2006 revision of Phyllanthaceae.
Incertae sedis: Chonocentrum
Subfamily Antidesmatoideae 6 tribes
- Tribe Bischofieae 1 genus
- Tribe Uapaceae 1 genus
- Tribe Spondiantheae 1 genus
- Tribe Scepeae 8 genera
- Tribe Jablonskieae 2 genera
- Tribe Antidesmateae 5 subtribes
Subfamily Phyllanthoideae 4 tribes
- Tribe Bridelieae 5 subtribes
- Subtribe Securineginae 2 genera
- Subtribe Saviinae 5 genera
- Subtribe Pseudolachnostylidinae 4 genera
- Subtribe Keayodendrinae 1 genus
- Subtribe Amanoinae 1 genus
- Tribe Phyllantheae 5 genera
- Tribe Wielandieae 2 subtribes
- Tribe Poranthereae 8 genera
The list of 54 genera below is from the 2006 revision of Phyllanthaceae by Petra Hoffmann and co-workers. In their treatment, Blotia and Petalodiscus were sunk into Wielandia and Richeriella into Flueggea. Breynia, Glochidion, Reverchonia, and Sauropus were recommended to be subsumed into Phyllanthus, but many new species combinations must be published to effect this change. Genera previously considered as the tribe Drypeteae are now placed in the separate family Putranjivaceae.
The revision of Phyllanthaceae by Hoffmann and co-authors was based on two molecular phylogenetic studies that were published in 2005. Since the revision, phylogenetic studies have been done on some of the tribes.
The phylogenetic tree shown below is based on the results of several studies. Fifty-one genera are represented. Chonocentrum(Phyllanthaceae, incertae sedis), and three members of the tribe Scepeae (Ashtonia, Distichirrhops, and Nothobaccaurea) have not yet been sampled for DNA. Chonocentrum is known from only a single specimen collected in the 1850s.
- Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x.
- Kenneth J. Wurdack and Charles C. Davis. 2009. "Malpighiales phylogenetics: Gaining ground on one of the most recalcitrant clades in the angiosperm tree of life." American Journal of Botany 96(8):1551-1570. (see External links below)
- Petra Hoffman. 2007. "Phyllanthaceae" pages 250-252. In: Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. Flowering Plant Families of the World. Firefly Books: Ontario, Canada. ISBN 978-1-55407-206-4.
- Anthony J. Huxley, Mark Griffiths, and Margot Levy (editors). 1992. The New Royal Horticultural Society Dictionary of Gardening. The Macmillan Press Limited, London; The Stockton Press, New York. ISBN 978-0-333-47494-5 (set)
- Hashendra S. Kathriarachchi; Petra Hoffmann; Rosabelle Samuel; Kenneth J. Wurdack & Mark W. Chase (2005). "Molecular phylogenetics of Phyllanthaceae inferred from five genes (plastid atpB, matK, 3'ndhF, rbcL, and nuclear PHYC)". Molecular Phylogenetics and Evolution. 36 (1): 112–134. doi:10.1016/j.ympev.2004.12.002. PMID 15904861.
- Samuel, Rosabelle; Kathriarachchi, Hashendra S.; Hoffmann, Petra; Barfuss, Michael H.J.; Wurdack, Kenneth J.; Davis, Charles C.; Chase, Mark W. (2005). "Molecular phylogenetics of Phyllanthaceae: evidence from plastid matK and nuclear PHYC sequences" (PDF). American Journal of Botany. 92 (1): 132–141. doi:10.3732/ajb.92.1.132. PMID 21652393.
- Kathriarachchi, Hashendra S.; Samuel, Rosabelle; Hoffmann, Petra; Mlinarec, Jelena; Wurdack, Kenneth J.; Ralimanana, Hélène; Stuessy, Tod F.; Chase, Mark W. (2006). "Phylogenetics of tribe Phyllantheae (Phyllanthaceae) based on nrITS and plastid matK DNA sequence data". American Journal of Botany. 93 (4): 637–655. doi:10.3732/ajb.93.4.637. PMID 21646224.
- Hoffmann, Petra; McPherson, Gordon (2007). "Revision of Wielandia, including Blotia and Petalodiscus (Phyllanthaceae)". Annals of the Missouri Botanical Garden. 94 (3): 519–553. doi:10.3417/0026-6493(2007)94[519:ROWIBA]2.0.CO;2.
- 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. (see External links below)
- "Phyllanthaceae" In: Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website. In: Missouri Botanical Garden Website. (see external links below)
- Hoffmann, Petra (2008). "Revision of Heterosavia, status novus, with notes on Gonatogyne and Savia (Phyllanthaceae)". Brittonia. 60 (2): 136–166. doi:10.1007/s12228-008-9012-5. S2CID 34814559.
- Vorontsova, Maria S.; Hoffmann, Petra (2008). "A phylogenetic classification of tribe Poranthereae (Phyllanthaceae)". Kew Bulletin. 63 (1): 41–59. doi:10.1007/s12225-007-9012-8. S2CID 21278789.
- Hoffmann, Petra; Kathriarachchi, Hashendra S.; Wurdack, Kenneth J. (2006). "A Phylogenetic Classification of Phyllanthaceae". Kew Bulletin. 61 (1): 37–53.
- Webster, Grady L. (1994). "Classification of the Euphorbiaceae". Annals of the Missouri Botanical Garden. 81 (1): 3–32. doi:10.2307/2399908. JSTOR 2399908.
- John Hutchinson. "Euphorbiaceae" pages 329-330. In: The Families of Flowering Plants, Third Edition (1973). Oxford University Press: London.
- Reveal, James L.; Hoffmann, Petra; Doweld, Alexander; Wurdack, Kenneth J. (2007). "(1765) Proposal to conserve the name Phyllanthaceae.". Taxon. 56 (1): 266.
- Mark W. Chase et alii (42 authors). 1993. "Phylogenetics of seed plants: an analysis of nucleotide sequences from the plastid gene rbcL." Annals of the Missouri Botanical Garden 80(3):528-580.
- Toru Tokuoka. 2007. "Molecular phylogenetic analysis of Euphorbiaceae sensu stricto based on plastid and nuclear DNA sequences and ovule and seed character evolution." Journal of Plant Research 120(4):511-522. (see External links below).
- Charles C. Davis, Maribeth Latvis, Daniel L. Nickrent, Kenneth J. Wurdack, and David A. Baum. 2007. "Floral Gigantism in Rafflesiaceae." Science 315(5820):1812. (see External links below).
- Petra Hoffmann, Don Kirkup, Aimee Galster, Gill Challen, and Alan Radcliffe-Smith. 2005 onward. Interactive Key to the Genera of Euphorbiaceae sensu lato. In: Index of /herbarium/keys. (see External links below).
- Alan Radcliffe-Smith. 2001. Genera Euphorbiacearum. Kew Publishing, Royal Botanic Gardens, Kew: Richmond, England.
- Webster, Grady L. (1994). "Synopsis of the genera and suprageneric taxa of Euphorbiaceae" (PDF). Annals of the Missouri Botanical Garden. 81 (1): 33–144. doi:10.2307/2399909. JSTOR 2399909.
- W. John Hayden & Sheila M. Hayden (1996). "Two enigmatic biovulate Euphorbiaceae from the Neotropics: relationships of Chonocentron and the identity of Phyllanoa". American Journal of Botany. 83 (6): 162. doi:10.2307/2445447. JSTOR 2445447.
- Vorontsova, Maria S.; Hoffmann, Petra; Maurin, Olivier; Chase, Mark W. (2007). "Phylogenetics of tribe Poranthereae (Phyllanthaceae)". American Journal of Botany. 94 (12): 2026–2040. doi:10.3732/ajb.94.12.2026. PMID 21636396.
|Wikimedia Commons has media related to Phyllanthaceae.|
- Wurdack, KJ; Davis, CC (August 2009). "Malpighiales phylogenetics: Gaining ground on one of the most recalcitrant clades in the angiosperm tree of life". Am. J. Bot. 96 (8): 1551–70. doi:10.3732/ajb.0800207. PMID 21628300.
- Kathriarachchi, H; Hoffmann, P; Samuel, R; Wurdack, KJ; Chase, MW (July 2005). "Molecular phylogenetics of Phyllanthaceae inferred from five genes (plastid atpB, matK, 3'ndhF, rbcL, and nuclear PHYC)". Mol. Phylogenet. Evol. 36 (1): 112–34. doi:10.1016/j.ympev.2004.12.002. PMID 15904861.
- Pruesapan, K. (2008). "Delimitation of Sauropus (Phyllanthaceae) Based on Plastid matK and Nuclear Ribosomal ITS DNA Sequence Data". Annals of Botany. 102 (6): 1007–1018. doi:10.1093/aob/mcn193. PMC 2712409. PMID 18854375.
- Phyllanthaceae At: Angiosperm Phylogeny Website At: Missouri Botanical Garden Website
- Tokuoka, T (July 2007). "Molecular phylogenetic analysis of Euphorbiaceae sensu stricto based on plastid and nuclear DNA sequences and ovule and seed character evolution". J. Plant Res. 120 (4): 511–22. doi:10.1007/s10265-007-0090-3. PMID 17530165. S2CID 19614584.
- Davis, C. C. (2007). "Floral Gigantism in Rafflesiaceae". Science. 315 (5820): 1812. Bibcode:2007Sci...315.1812D. doi:10.1126/science.1135260. PMID 17218493. S2CID 27620205.
- Key to Euphorbiaceae sensu lato At: Index of /herbarium/keys