Neotropical Phyllanthaceae

Marcos José da Silva

Universidade Estadual de Campinas (UNICAMP), Brazil. 

Description

Herbs, shrubs or trees, monoecious or dioecious, lacking latex and extrafloral nectaries. Leaves alternate, spiral to distichous, or rarely opposite, simple or rarely compound, margin entire or less frequently dentate, embedded foliar glands rare, petiole usually present, cylindrical to angulose; leaf blade membranaceous to coriaceous, stomata paracytic or anomocytic, stipules usually present and persistent, or rarely absent, eglandular, scariose with the margin entire or lacerate-denticulate; latex absent, indumentum simple, less frequently branched, or lepidote (Hyeronima Allemão) venation brochidodromous. Inflorescences axillary or less frequently terminal, racemose or spicate, or seldom paniculate or glomerulate (cymes), or reduced to solitary flowers; bracts eglandular and inconspicuous. Flowers hypogynous, actinomorphic, unisexual, pistillode or staminode absent or present; perianth mostly inconspicuous and usually monochlamydeous or more rarely dichlamydeous; sepals 4-6, imbricate, free or variously connate toward to base, petals usually 5, imbricate, free; androecium (2-)-4-8 (-50) stamens, filaments free or united in column, anthers introrse or extrorse, tetrasporangiate and dithecal, opening by longitudinal or traverse slits, pollen grains mostly 3-4-colporate (rarely porate, periporate in Phyllanthus L.), exine semitectate, rarely echinate (Amanoa Aubl.), male gametophyte binucleate, nectary -disk commonly present (absent in Didymocistus Kuhlm.), entire or dissected, extrastaminal or seldom intrastaminal in male flowers, and annular or dissected in female flowers; ovary (1) 2-5 (-20)-carpelar, styles connate basally and  often bifid; ovules 2 (rarely 1) in each locule, anatropous or hemitropous, nucellar beak sometimes prominent. Fruits typically a capsular schizocarp with the mericarps separating elastically from the persistent columella and opening ventrally to release seeds, or seldom drupaceous (Hyeronima and Keayodendron Leandri). Seeds trigonous, ovoid, ellipsoid or rounded, caruncle lacking or rudimentary, coat dry or fleshy, and endosperm present or absent. The commonest base chromosome numbers are 12 or 13.

Notes on delimitation

  • Phyllanthaceae present a variety of growth forms, and is characterized morphologically and differentiated from the Euphorbiaceae s.s by the absence of latex and extrafloral nectaries in the leaves, bi-ovulated ovary, explosively dehiscent fruit, and seed without caruncle.
  • It includes, phylogenetically, most of old Euphorbiaceae -Phyllanthoideae. This clade appears as a monophyletic group, and it consists of two sister clades, that typically correspond to the distribution of tanniniferous leaf epidermal cells and inflorescence structure. The first clade possesses fasciculate inflorescences and includes Lingelsheimia, Dicoelia and Phyllanthoideae, while the second clade includes tanniniferous Hymenocardieae, and Antidesmatoideae (Kathriarachchi et al. 2005, Hoffmann et al. 2006).
  • It is one of the largest and most diverse lineages in the Mapighiales, clade Eurosid I (Samuel et al. 2005).
  • Systematically, the Phyllanthaceae are subdivided into two subfamilies (Phyllanthoideae Kostel. and Antidesmatoideae Hurus.) and 10 tribes (Poranthereae Grüning, Bridelieae Müll. Arg., Wielandieae Baill. ex Hurus., Phyllantheae Dumort., Antidesmateae Benth., Jabloskieae Petra Hoffm., Scepeae Horan., Spondiantheae G.L. Webster, Uapaceae Hutch., and Bischofieae Hurus.), following Hoffmann et al. 2006.

Distribution in the Neotropics

Phyllanthaceae are represented by 19 genera in the Neotropics, and occur in several vegetation types, especially in rainforest, savanna and associated ecosystems:

  • Amanoa Aublet - It is a genus of 16 species widely distributed through the tropics of Africa and the Americas (Hayden & Urban 1990). In the Neotropics it is represented by 13 reasonably well-marked species that occur specially in the northern portion of South America (Brazil, Colombia, Equador, Venezuela and French Guiana) or along the rainforests, montane and gallery forests and savanna: A. oblongifolia Müll. Arg (Amazon Basin, Brazil and Venezuela), A. cupatensis Huber and A. almerindae Leal (Venezuelan and Brazilian savanna ), A. guianensis Aublet, (Venezuela, Central and N South America), and A. congesta W.J. Hayden (French Guiana and Amazon Delta region of Amapá and Pará, Brazil).
  • Andrachne L. - In the restricted circumscription adopted by Webster (1994a) Andrachne includes about 15 species with a primarily Tethyan distribution from Persia through the Mediterranean to the West Indies, with one species (A. microphylla Baill.) disjunct from Baja California to Pacific South America (Peru).
  • Astrocasia B.L.Rob & Greenm. - This is a Neotropical genus of six species (A. austinii (Standl.) G.L. Webster, A. diegoae J. Jiménez Ram. & Mart. Gord., A. jacobinensis (Müll.Arg.) G.L. Webster, A. peltata Standl., A. phyllanthoides B.L.Rob.& Millsp., A. populifolia I.M. Johnst. and A. tremula (Griseb.) G.L. Webster) distributed from Mexico and Cuba to Bolivia and eastern Brazil. Its species grow mainly in savanna vegetation in open areas.
  • Breynia J.R. & G. Forster - This is a complex genus that includes c.30 species that are highly variable. It is distributed from tropical eastern Indonesia, tropical Asia, and Pacific islands. In the Neotropics B. disticha J. R. & Forster is widely cultivated as an ornamental.
  • Celianella Jabl. - Monotypic (C. montana Jabl.) of Venezuela (Amazonas, Bolivar) where it inhabits scrub-savanna on tepui summits.
  • Chascotheca Urban - Neotropical genus (Cuba and Hispaniola) with two species: C. neopeltandra Urb. and C. triplinervia (Müll.Arg.) G.L. Webster. According to Webster (1994a), C. dominguensis (Urb.) Urb. is probably a synonym of  C. neopeltandra Urb. 
  • Chonocentrum Pierre ex Pax & Hoffm. - A monotypic and endemic genus (C. cyathophorum [Müll. Arg.] Pax & Hoffm.) of South America.
  • Discocarpus Klotzsch - According to Hayden & Hayden (1996) Discocarpus possesses three species distributed through the rainforest and swamp forest of Amazonian Brazil, Guyana, Suriname, Colombia, Peru, and Venezuela. However, Fiaschi and Cordeiro (2005) added one more species:  Discocarpus pedicellatus Fiaschi & Cordeiro. This species and D. essequiboensis Klotzsch occurs in the semideciduous forests of eastern (Bahia, Maranhão) and central (Goiás) Brazil.
  • Didymocistus Kuhlmann - A monotypic genus (D. chrysadenius Kuhlm.) of Amazonian Brazil.
  • Flueggea Willd. - About 13 species widespread in tropical to warm temperate regions. Flueggea hilariana Baill. (Brazil), F. acidothamnus Griseb. (Cuba), F. elliptica (Spreng.) Baill. (Equador), and F. schuechiana (Müll.Arg.) G.L.Webster (Brazil, Pernambuco) are the only species in the genus in the Neotropics, where they grow in the edges of secondary forest.
  • Gonatogyne Klotzsch ex Müll. Arg. - A monotypic genus (G. brasiliensis [Baill.] Müll. Arg.) of Brazil.
  • Hyeronima Allemão - A Neotropical genus of more than 20 described species, of which 10 were recognized by Franco (1990) for South America. Hyeronima oblonga (Tul.) Müll. Arg. and H. alchorneoides Allemão are widely distributed in the rainforest and submontane forest of the Neotropics.
  • Jablonskia Webster - Monotypic genus (J. congesta G.L. Webster) confined to Amazonian South America (Guianas and Amazon Basin SW. to Peru). It is largely associated with watercourses or within rainforests.
  • Leptopus Descaine - A pantropical genus with approximately 10 species, of which Leptopus phyllanthoides (Nutt.) G.L. Webster is the most frequent from southern United States to Mexico, and L. orinocensis Klotzsch & Garcke in the forests of the north of Brazil and along the Orinoco River.
  • Margaritaria L. f. - This comprises 14 species distributed thorough tropical America, Africa, Asia, and Australia. Margaritaria nobilis L.f. is the most widespread species of genus in the Neotropics, growing in seasonal, rain- and gallery forest (Gillespie, 1993), while M. hotteana (Urb. & Ekman) G.L. Webster, and M. scandens (Wright & Griseb.) G.L. Webster, are endemic to Haiti and the Bahamas, respectively.
  • Meineckia Baill. - Webster (1994a) indicated that this genus possessed about 20 species with a disjunct distribution in the New World and Old World. In the Neotropics it occurs from Mexico to Colombia and Brazil (represented by M. capillipes (Blake) G.L. Webster, M. neogranatensis (Müll. Arg.) G.L. Webster).
  • Phyllanthus L. - a pantropical genus with more than 1,000 species. In the Neotropics it is represented by approximately 200 species distributed from the southeast of the United States to Argentina, including the West Indies (Webster 2002). In Brazil the genus is represented by ca. 107 species in several ecosystems, being more frequent in open vegetation, e.g. Cerrado, Caatinga, and campo rupestre, or in disturbed areas (Silva & Sales 2003, 2007).
  • Richeria Vahl - A genus with five species distributed through the Americas. Richeria grandis Vahl is a species most frequently distributed in riparian forest of the Neotropics.
  • Savia Willd. - A genus with approximately 25 species, distributed mainly in the West Indies and Madagascar. Savia dictyocarpa Müll. Arg. frequently occurs in the Atlantic Forest of southern Brazil.

Distinguishing characters (always present)

Phyllanthaceae are characterized morphologically by the following characters which seperate it from the Euphorbiaceae s.s:

  • Absence of latex.
  • Ovary bi-ovulated.
  • Seeds without caruncle.

Other important characters

Key differences from similar families

Key  to Identification of Phyllanthaceae and related families in the Neotropics

1. Plants usually pubescent; latex often present, caustic, milky or transparent; extrafloral nectaries present and diverse; ovary commonly uni-ovulate; fruits usually capsular; seeds carunculate....Euphorbiaceae
1. Plants usually glabrous, or more rarely pubescent, hairs if present usually simple; latex absent; extrafloral nectaries absent; ovary with 2 ovules per locule; fruits capsular to drupaceous; caruncle present or absent ... 2

2. Leaves often arranged in 2 rows; cataphylls lacking on orthotropic axes; petals absent; pollen grains colpoidorate to porate, sexine with conspicuous spines; ovules with obturator funicular; seeds usually carunculate....Picrodendraceae
2. Leaves often arranged in one plane; cataphylls on orthotropic axes; petals present or absent; pollen grains tricolporate to porate, sexine without conspicuous spines; ovules with obturator placental; seeds without caruncle....Phyllanthaceae

Number of genera

Phyllanthaceae are a pantropical family and comprise approximately 60 genera and 2,000 species.

The Phyllanthaceae in the Neotropics are represented by 19 genera listed below:

  • Amanoa Aubl.
  • Andrachne L.
  • Astrocasia B.L.Rob. & Greenm.
  • Breynia G. & F. Forster
  • Celianella Jablonski
  • Chascotheca Urban
  • Chonecentrum Pierre ex Pax & Hoffmann
  • Didymocistus Kuhlm.
  • Discocarpus Klotzsch
  • Flueggea Willd.
  • Gonatogyne Muell. Arg.
  • Hyeronima Allemão
  • Jablonskia Webster
  • Leptopus Descaine
  • Margaritaria L.f.
  • Meineckia Baillon
  • Phyllanthus L.
  • Richeria Vahl
  • Savia Willd.

Notable genera and distinguishing features

  • Phyllanthus is the largest genus in the Phyllanthaceae (more than 1,000 species), and has a remarkable diversity of growth forms - annual and perennial herbaceous, arborescent to climbing, terrestrial or floating aquatic (P. fluitans Müll. Arg.), with branches normal or modified into phylloclades.
  • Despite their variety, almost all Phyllanthus species express a specific type of growth called "phyllanthoid branching" in which the leaves on the main (vertical) plant axes are reduced to cataphylls while leaves on the plagiotropic (horizontal) axes are deciduous and floriferous.
  • The flowers in the genus are always unisexual, extremely small and usually possess a disk in both sexes, while the fruits are capsular and possess trigonous seeds, covered by a fine, dry and brownish seed-coat. In most of the species the seed-coat is verrucose or finely reticulate (Webster 1956, 1957, 1958).
  • Molecular phylogenetic studies of Phyllanthus found three out of its eight subgenera to be polyphyletic and the genus in its traditional circumscription to be paraphyletic (Kathriarachchi et al., 2005, 2006). Breynia Forst. & Forst. f., Glochidion Forst. & Forst. f., Reverchonia A.Gray and Sauropus Blume are embedded in Phyllanthus. If all these genera are united with Phyllanthus, then the number of  Phyllanthus species increases from 833 to 1269 (Govaerts et al., 2000) and a giant and morphologically heterogeneous genus is created.

Status

  • Native - Amanoa Aubl., Andrachne L., Flueggea Willd., Leptopus Descaine, Margaritaria L.f., Meineckia Baillon, Phyllanthus L. and Savia Willd.
  • Cultivated - Breynia Forst. & Forst. f.
  • Endemic - Astrocasia Robinson & Greenman, Celianella Jabl., Chascotheca  Urban, Chonocentrum Pierre ex Pax & Hoffmann, Discocarpus Klotzsch, Didymocistus Kuhlm., Gonatogyne Klotzsch ex Müll. Arg., Hyeronima Allemão, Jablonskia Webster and Richeria Vahl

General notes

  • Phyllanoa was cited by Webster (1994b) for Euphorbiaceae subfamily Phyllanthoideae (= Phyllanthaceae). However, Phyllanoa according to Hayden & Hayden (1996) belongs to the Violaceae.
  • The generic boundaries in the closely related complex of Phyllanthus, Breynia, Sauropus and Glochidion are unclear and further studies are necessary.

Important literature

Fiaschi, P. & Cordeiro, I. 2005. Discocarpus pedicellatus, a new species of Phyllanthaceae (Euphorbiaceae s.l.) from southern Bahia, Brazil, Brittonia, 57(3): 248-251.

Franco, P. 1990. The genus Hyeronima (Euphorbiaceae) in South America. Bot. Jahrb. Syst. 111:297-346.

Gillespie, L. G. 1993. Euphorbiaceae of the Guianas: Annotated Species Checklist and Key to the Genera, Brittonia 45 (1): 56-94.

Govaerts, R., Frodin, D.G. & Radcliffe-Smith, A. 2000. World checklist and bibliography of Euphorbiaceae (with Pandaceae). v. 4. London: Royal Botanic Gardens, Kew.

Hayden, W. J. 1990. Notes on neotropical Amanoa (Euphorbiaceae). Brittonia 42: 260-270.

Hayden, S. M., & W. J. Hayden. 1996. A revision of Discocarpus (Euphorbiaceae). Ann. Missouri Bot. Gard. 83: 153-167.

Hoffmann, P., Kathriarachchi, H. & Wurdack, K.J. 2006. A phylogenetic classification of Phyllanthaceae (Malpighiales; Euphorbiaceae s.l.). Kew Bulletin 61: 37-53.

Kathriarachchi, H., Hoffmann, P., Samuel, R., Wurdack, K.J. & Chase, M.W. 2005. Molecular phylogenetics of Phyllanthaceae inferred from 5 genes (plastid atpB, matK, 3' ndhF, rbcL) and nuclear PHYC. Molecular Phylogenetics and Evolution 36: 112-134.

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.

Samuel, R., Kathriarachchi, H., Hoffmann, P., Barfuss, M. H. J., Wurdack, K. J., Davis, C. C. & Chase, M.W. 2005. Molecular phylogenetics of Phyllanthaceae: evidence from plastid matK and nuclear PHYC sequences. American Journal of Botany 92: 132-141.

Silva, J.M. & Sales, M.F. 2003. O gênero Phyllanthus L. (Phyllantheae - Euphorbiaceae Juss.) no bioma Caatinga do estado de Pernambuco - Brasil. Rodriguésia 54: 101- 126.

Silva, J.M. & Sales, M.F. 2007. Phyllanthus L. (Phyllanthaceae) em Pernambuco, Brasil. Acta Botânica Brasílica 21: 79-98.

Webster, G.L. 1956. A monographic study of the West Indian species of Phyllanthus Journal of the Arnold Arboretum 37: 91-122, 217-268, 340-359.

Webster, G.L. 1957. A monographic study of the West Indian species of Phyllanthus L. Journal of the Arnold Arboretum 38: 51-80, 170-198, 295-373.

Webster, G.L. 1958. A monographic study of the West Indian species of Phyllanthus. Journal of the Arnold Arboretum 39: 49-100, 111-212.

Webster, G.L. 1994a. Classification of the Euphorbiaceae. Annals of the Missouri Botanical Garden 81: 3: 32.

Webster, G.L. 2002. A synopsis of the Brasilian taxa of Phyllanthus section Phyllanthus (Euphorbiaceae). Lundellia 5: 1-26.

How to cite

Silva, M.J. (2009). Neotropical Phyllanthaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Phyllanthaceae.htm.