Phyllanthaceae comprises about 2000 species.[6][7] 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.[8]
Some of the genera have recently been sunk into others, while other genera have recently been divided.[9][10] 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).[11]
The description here is from Hoffmann,[4][14] except for a few additions from Webster[15] and Hutchinson [16] 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.
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.[13]
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.
A
nectary disk is often present. It may be in the form of a ring, or divided into segments. The
stamens are three to ten in number, or rarely more, free or variously fused.
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.[16] 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.[15] 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
generbcL from a large number of
seed plants.[18] 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.[19][20]Pandaceae, Phyllanthaceae,
Picrodendraceae,
Putranjivaceae,
Peraceae, and
Centroplacaceae have been removed from it.[11]
The obsolete, older concept of Euphorbiaceae, known as Euphorbiaceae
sensu lato, is sometimes still used for continuity and convenience.[21] 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.[15][22][23]
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.[11]Paradrypetes is in
Rhizophoraceae.[3]Phyllanoa is known only from a single specimen. In 1996, this was examined and found to be a species of Rinorea (
Violaceae).[24]
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.
A 2006 revision of Phyllanthaceae by Petra Hoffmann and co-authors recognized 54 genera. 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.[14] Plants of the World Online still accepts Breynia and Glochidion,[25] and subsumes Sauropus into Breynia.[26]
The revision of Phyllanthaceae by Hoffmann and co-authors was based on two
molecular phylogenetic studies that were published in 2005.[6][7] Since the revision, phylogenetic studies have been done on some of the tribes.[8][27]
The phylogenetic tree shown below is based on the results of several studies.[8][12][13][14] 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.[24]
In the phylogeny shown below, statistical support for the clades was measured by
bootstrap percentage. All branches shown below have
maximum parsimony bootstrap support of at least 70%.
^
abKenneth 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 Botany96(8):1551-1570. (see External links below)
^
abcPetra 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.
ISBN978-1-55407-206-4.
^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.
ISBN978-0-333-47494-5 (set)
^
abcHashendra 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.
PMID15904861.
^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 Botany102(6):1007-1018. (see External links below)
^
abc"Phyllanthaceae" In: Peter F. Stevens (2001 onwards). Angiosperm Phylogeny Website. In: Missouri Botanical Garden Website. (see external links below)
^
abHoffmann, 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.
S2CID34814559.
^
abJohn 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 Garden80(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 Research120(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." Science315(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.
^
abW. 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.
JSTOR2445447.
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.
PMID21628300.
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.
PMID15904861.
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.
PMID17530165.
S2CID19614584.