Neotropical Eriocaulaceae

P.T. Sano*, M. Trovů* and A.M. Giulietti**

* Universidade de S„o Paulo (USP), S„o Paulo, Brazil.
** Universidade de Feira de Santana (UEFS), Feira de Santana, Bahia, Brazil. 

Description

Herbs annual or perennial, aquatic or terrestrial; rhizome vertical or horizontal or corm, covered by remaining leaf sheaths, with axillary trichomes, and glabrous to hirsute roots; aerial stems, if present, branched or not. Leaves in rosette, rarely distributed along the stem, generally spirally arranged, rarely spiro-distichous, spiro-tritichouso or pseudo-verticillate, simple, lanceolate to linear, membranaceous to coriaceous, fenestrated or not, with expanded sheaths or not; scapes terminal or axillary, generally surrounded by a cylindrical spathe with apex truncated or acute. Inflorescence capitulum with many sterile involucral bracts. Flowers small, about 2 or 4 mm long generally pedicellate, unisexual, with staminodes or pistillodes or rarely hermaphrodite, generally more than 50 per capitula, with centripetal formation, with bracts or not; dichlamydeous, actinomorphic or zygomorphic; sepals 3-2, free or rarely fused; petals 3-2, rarely reduced to a hairy lobe, free or fused, with glands or not, with anthophore or not. Staminate flowers with 2-4 or 6 stamens, filament free, cylindrical or flattened, anthers 2-sporangiate or 4-sporangiate, dehiscing by longitudinal slits, dorsifixed or basifixed, with pistillodes. Pistillate flowers with superior ovary, 2-3-locular, ovules 1 per locule, basal placentation; styles 2-3 fused, stigmatic portions completely fused or not, with nectariferous portions or not, with staminodes or not. Fruit dehiscent capsule or rarely indehiscent achene; pericarp membranaceous; seeds 1 per locule, rarely reduced to 1 per fruit, seed coat reticulate, striate, rough or smooth, embryo not differentiated, endosperm amilaceous.

Notes on delimitation

  • Close to Xyridaceae and Mayacaceae, it is currently placed within the order Poales (APG II, 2003).

Distribution in the Neotropics

Eriocaulaceae are widely distributed in the Neotropics. Species occur in different habitats, but most of them are distributed in the Brazilian campo rupestre vegetation, in the Venezuelan Tepuis, and in the Brazilian cerrado (savanna).

  • Actinocephalus (Bong.) Sano - Endemic, restricted to Brazil.
  • Blastocaulon Ruhland - Endemic, restricted to EspinhaÁo Range, Brazil.
  • Eriocaulon L. - Pantropical, widely distributed in Neotropics.
  • Leiothrix Ruhland - Endemic, restricted to South America.
  • Paepalanthus Mart. - Widely distributed in Neotropics, few species in Africa.
  • Philodice Mart. - Endemic, tropical South America.
  • Rondonanthus Herzog - Endemic, restricted to Tepuis Highlands in Venezuela, Guyana and Brazil.
  • Syngonanthus Ruhland - Widely distributed in Neotropics, few species in Africa.
  • Tonina Aubl. - Endemic, widely distributed in tropical Central and South America.

Distinguishing characters (always present)

  • Eriocaulaceae are easily recognized by possessing unisexual flowers grouped in a dense capitulum.

Other important characters

  • Leaves arranged in a basal rosette.
  • Capitula subtended by a scape, which is surrounded by a spathe.
  • Spiraperturate pollen grains.

Key differences from similar families

Number of genera

Eriocaulaceae comprises 9 genera with ca. 850 spp. in Neotropics.

  • Actinocephalus - 31 spp.
  • Blastocaulon - 5 spp.
  • Eriocaulon - ca. 60 spp.
  • Leiothrix - ca. 50 spp.
  • Paepalanthus - ca. 500 spp.
  • Philodice - 2 spp.
  • Rondonanthus - 6 spp.
  • Syngonanthus - ca. 200 spp.
  • Tonina - 1 sp.

Useful tips for generic identification

Except Actinocephalus and Eriocaulon that can be easily recognized in the field, all other genera are exclusively defined by a few floral characters, which are better observed under a stereomicroscope.

Key to the genera of Neotropical Eriocaulaceae

1. Fenestrated leaves; flowers diplostemonous; petals glandular.... Eriocaulon
1. Non-fenestrated leaves; isostemonous flowers; petals eglandular .... 2

2. Pistillate flowers with linear staminodes or complete stamens .... Rondonanthus
2. Pistillate flowers with scale-like staminodes .... 3

3. Style with stigmatic and nectariferous portions separating at different levels .... Leiothrix
3. Style with stigmatic and nectariferous portions separating at same level.... 4

4. Pistillate flowers with petals reduced to a hairy lobe .... Tonina
4. Pistillate flowers with conspicuous petals .... 5

5. Pistillate flowers with petals fused at middle .... 6
5. Pistillate flowers with petals free.... 7

6. Anthers 2-sporangiate .... Philodice
6. Anthers 4-sporangiate .... Syngonanthus

7. Umbellate inflorescence in paracladial axis.... Actinocephalus
7. Paracladial axis absent.... 8

8. Anthers 2-sporangiate.... Blastocaulon
8. Anthers 4-sporangiate.... Paepalanthus

Notable genera and distinguishing features

  • Actinocephalus - umbellate inflorescences in paracladial axis, trimerous flowers, and completely fused stigmatic portions.
  • Eriocaulon - fenestrated leaves, diplostemonous flowers, and glandular petals.
  • Leiothrix- pistillate flowers with free petals, style branching at different levels, 4-sporangiate anthers, and seed coat striate.
  • Paepalanthus - pistillate flowers with free petals, style branching at the same level, and 4-sporangiate anthers.
  • Syngonanthus - pistillate flowers with fused petals, style branching at the same level, and 4-sporangiate anthers.

Status

  • Actinocephalus - Native, endemic.
  • Blastocaulon - Native, endemic.
  • Eriocaulon - Native.
  • Leiothrix - Native, endemic.
  • Paepalanthus - Native.
  • Philodice - Native, endemic.
  • Rondonanthus - Native, endemic.
  • Syngonanthus - Native.
  • Tonina - Native, endemic.

General notes

  • Although Eriocaulaceae can be easily recognized among the other Monocotyledons by possessing small flowers arranged in dense capitula, identifying the genera and the species is not a simple task.
  • The genera are usually defined by floral characteristics that are difficult to see in the field.
  • Species identification is also not simple for several reasons.
  • The habit and indumentum play a central role, but can vary according to the environment.
  • The last revision for the whole family was carried out by Ruhland (1903) and needs to be revised.
  • In addition, Silveira (1908, 1928) published 183 species without any key, and Harold Moldenke published dozens of species, also without any key.
  • Some species have considerable economic importance in Brazil, especially those of the genus Syngonanthus.
  • The scapes and inflorescences of these species are collected and dried in the sun, to be sold as ornamental objects and often exported from Brazil to different countries as "everlasting plants".
  • Some species in the states of Bahia, Minas Gerais, and Tocantins are critically endangered due to over-exploitation (Giulietti et al. 1988, 1996; Schmidt et al. 2007).
  • Phylogenetic studies (Andrade 2007, Unwin 2004) suggest that some modifications in the family taxonomy should be done. Blastocaulon emerges as polyphyletic and should be merged within Paepalanthus. Philodice clusters within species of Syngonanthus, and in this case, a proposal to conserve the name Syngonanthus against Philodice, and its synonymisation would be relevant. Two sections of Syngonanthus form a well supported clade segregated from the rest of the genera, and the re-establishment of Comanthera L.B.Sm. to congregate these species is regarded.

Important literature

Andrade, M. J. G. 2007. Filoggonia e taxonomia em Eriocaulaceae Neotropicais. Ph.D. thesis. Universidade Estadual de Feira de Santana, Feira de Santana.

Bongard, M. 1831. Essai monographique sur les especes d'Eriocaulon du Bresil. Meem. Acad. Imp. St. Pťtersbourg, Ser. 6, Sci Math 1:601-655.

Costa, F. N. 2001. Flora da Serra do Cipo, MG: Blastocaulon Ruhland, Paepalanthus subg. Thelxinoe Ruhland e Paepalanthus subg. Paepalocephalus Ruhland pro parte (Eriocaulaceae). Dissertacao de Mestrado. Inst. Bioc. Univ. S. Paulo. Sao Paulo.

Costa, F. N. 2006. Recircunscricao de Actinocephalus (Koern.) Sano (Eriocaulaceae). Tese de Doutorado. Inst. Bioc. Univ. S. Paulo. Sao Paulo.

Giulietti, A. M. 1978. Os generos Eriocaulon L. e Leiothrix Ruhl. na Serra do Cipo, Minas Gerais, Brasil. Tese de Doutorado. Inst. Bioc., Univ. S. Paulo. Sao Paulo.

Giulietti, A. M. 1984. Estudos taxonomicos no gÍnero Leiothrix Ruhl. (Eriocaulaceae). Tese de Livre-DocÍncia. Inst. Bioc. Univ. S. Paulo. Sao Paulo.

Giulietti, A. M. 1996. Leiothrix Ruhland (Eriocaulaceae) No Estado da Bahia, Brasil. Sitientibus, serie ciencias biologicas 15: 61-82.

Giulietti, A. M. & L. R. Parra. 1995. Eriocaulaceae. In Stannard, B. (ed.) Flora of Pico das Almas, Bahia, Brazil. Royal Botanic Gardens. Kew.

Giulietti, A. M., M. G. L. Wanderley, H. M. Longhi-Wagner, J. R. Pirani, and L. R. Parra. 1996. Estudos em "sempre-vivas": taxonomia com enfase nas especies de Minas Gerais, Brasil. Acta Botanica Brasilica 10: 329-377.

Giulietti, N., A. M., Giulietti, J. R. Pirani, and N. L. Menezes. 1988. Estudos em sempre-vivas: importancia economica do extrativismo em Minas Gerais, Brasil. Acta Botanica Brasilica 1: 179-193.

Hensold, N. C. 1988. Morphology and systematics of Paepalanthus subgenus Xeractis (Eriocaulaceae). Syst. Bot. Monographs 23.

Hensold, N. C. 1991. Revisionary studies in the Eriocaulaceae of Venezuela. Ann. Miss. Bot. Gard. 78:424-440.

Hensold, N. 1998. Flora da Serra do Cipo, Minas Gerais: Paepalanthus subg. Xeractis (Eriocaulaceae). Bol. Bot. Univ. Sao Paulo 17:207-218.

Hensold, N. 1999. Eriocaulaceae. In Steyermark, J. et al. (eds.) Flora of Venezuelan Guyana 5:1-58. MBG Press. Saint Louis.

Hensold, N. C. & A. M. Giulietti. 1991. Revision and redefinition of the genus Rondonanthus Herzog (Eriocaulaceae). Ann, Miss. Bot. Gard. 78:441-459.

Koernicke, F. 1863. Eriocaulaceae. In C. P. von Martius & A. W. Eichler (eds.) Flora brasiliensis 3(1):273-307. Typografia Regia. MŁnchen.

Moldenke, H. N. & L. B. Smith. 1976. Eriocaulaceae. In R. Reitz (ed.) Flora Ilustrada Catarinense. HerbŠrio Barbosa Rodrigues. ItajaŪ.

Parra, L. R. 1998. Flora da Serra do Cipo, Minas Gerais: Syngonanthus Ruhland (Eriocaulaceae). Bol. Bot. Univ. Sao Paulo 17:219-254.

Parra, L. R. 2000. Redelimitacao e Revisao de Syngonanthus sect. Eulepis (Bong. Ex. Koern.) Ruhland (Eriocaulaceae).Tese de Doutorado. Inst. Bioc. Univ. S. Paulo. Sao Paulo.

Rocha, A. E. S. 2004. Flora das restingas do estado do Para APA de Algodoal/Maiadeua. II - Eriocaulaceae P. Beuv. ex Desv. Hoehnea 31(2): 103-111.

Ruhland, W. 1903. Eriocaulaceae in A. Engler (ed.). Das Pflanzenreich 4(3):1-294. Wilhelm Engelmann. Leipzig.

Sano, P. T. 1998. Flora da Serra do Cipo, Minas Gerais: Paepalanthus sect. Actinocephalus - Eriocaulaceae. Bol. Bot. Univ. Sao Paulo 17:187-205.

Sano, P. T. 1999. Revisao de Actinocephalus (Koern.) Sano (Eriocaulaceae). Tese de Doutorado. Inst. Bioc. Univ. S. Paulo. Sao Paulo.

Schmidt , I. B., I. B. Figueiredo and A. Scariot. 2007. Ethnobotany and effects of harvesting on the population ecology of Syngonanthus nitens (Bong.) Ruhland (Eriocaulaceae), a NTFP from Jalapao Region, Central Brazil . Economic Botany 1(1): 73-85.

Silva, E. B. M. & A. M. Giulietti. 2000. Eriocaulaceae no morro do Pai Inacio (Palmeiras) e Serra da Chapadinha (Lencois), Chapada Diamantina, Bahia, Brasil. Sitientibus sťrie CiÍncias Biologicas 1: 15-32.

Silveira, A. A. 1908. Flora e serras mineiras. Imprensa Official. Belo Horizonte.

Silveira, A. A. 1928. Floralia montium vol. 1. Imprensa Official. Belo Horizonte.

StŁtzel, T. 1998. Eriocaulaceae. In: Kubitzki, K. (ed.) Flowering Plants: The Families and Genera of Vascular Plants. Springer-Verlag. Berlin. 

Tissot-Squalli H., M. L. 1997. Monographische Bearbeitung von Paepalanthus subgenus Platycaulon. J. Cramer. Berlin.

Trovů, M., P. T. Sano, F. N. Costa & A. M. Giulietti. 2007. Flora Fanerog‚mica do Parque Nacional do Caparaů: Eriocaulaceae. Pabstia 17: 2 - 8.

Unwin, M. M. 2004. Molecular systematics of the Eriocaulaceae Martinov. Ph.D. thesis, Oxford, Miami University, Ohio.

How to cite

Sano, P.T., Trovů, M. & Giulietti, A.M. (2009). Neotropical Eriocaulaceae. In: Milliken, W., KlitgŚrd, 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/Eriocaulaceae.htm.