Neotropical Rapateaceae

Description

Herbs caespitose, perennial, often in swampy areas, frequently mucilaginous; rhizome short, erect or prostrate. Leaves distichous, spirodistichous or rosulate, often equitant, rarely petiolate (Rapatea longipes Spruce ex Körn., Saxo-fridericia aculeata Kornicke), sometimes with margin aculeate (Saxo-fridericia aculeata); leaf sheaths developed and invaginating; leaf blades ensiform, lanceolate or linear. Inflorescences compound, axillary or terminal, capituliform, usually involved by two or more spathes; spikelets few to many, pedicellate or sessile, comprising a single terminal flower surrounded by several sterile bracts; flower monocline, actinomorphic, or slightly zygomorphic, perianth in two differentiated whorls; sepals 3, rigid, papyraceous, or membranaceous, similar to bracts, hyaline at the base, free or connate; petals 3, white, yellow or red, sometimes with blotches, membranaceous, usually connate, with lobes lanceolate, ovate or obovate; stamens 6, adnate to the corolla tube, anthers basifixed, introrse, sometimes with terminal appendages, dehiscencing by 1, 2 or 4 apical or subapical pores or short slits; ovary superior, carpels 3, locules 3; ovules anatropous, 1-8 per locule, basal or axile placentation; stylus simple, erect; stigma capitate; loculicidal capsules. Seeds globose, oblong, striated or muricate, chalky endosperm.

Notes on delimitation

• Rapateaceae is placed within the order Poales (APG III, 2010) as a Bromeliaceae sister group.  Mayacaceae is close to Rapateaceae in some studies because both have poricidal anthers.
• Rapateaceae is organized in 5 tribes: Stegolepidieae, Schoenocephalieae, Saxofridericieae, Monotremaeae, Rapateeaea.

Distribution in the Neotropics

• Rapateaceae is restricted to the Neotropics with the exception of Maschalocephalus dinklagei Gilg & Schumann that occurs in West Africa. The center of species diversity of Rapateaceae are the lowlands Guyana Shield and the Amazon.

Distinguishing characters (always present)

• Mucilage cells, stomatal guard cells dumbell-shaped, uniseriate colleters, inflorescence capitate and scapose, anthers with pores or short slits, microsporogenesis simultaneous.

Number of genera

17 genera with 16 ocurring in the Neotropics ~100 spp.

• Amphiphyllum Gleason (1 sp.)  - Brazil and Venezuela.
• Cephalostemon Schomb.(5 spp.) - Brazil, Bolivia, Suriname and Venezuela.
• Duckea Maguire. (4 spp.) - Brazil, Colombia  and Venezuela.
• Epidryos Maguire. (3 spp.) - Brazil, Colombia, Equador, Guyana, Panamá  and Venezuela.
• Guacamaya Maguire. (1 sp.) - Colombia and Venezuela.
• Kunhardtia Maguire. (2 spp.) - Venezuela.
• Marahuacaea Maguire. (1 sp.) - Venezuela.
• Monotrema Koern. (5 spp.) - Brazil, Colombia and Venezuela.
• Phelpsiella Maguire. (1 sp.) - Venezuela.
• Potarophytum Sandw. (1 sp.) - Guyana.
• Rapatea Aubl. (27 spp.) - Brazil, Bolivia, Colombia, Ecuador, Guyana, French Guyana, Peru, Suriname and Venezuela.
• Saxofridericia Schomb.(7 spp.)  -  Brazil,  Colombia, French Guyana, Guyana, Suriname,  and Venezuela.
• Schoenocephalium Seub. (4 spp.)  - Brazil, Colombia and Venezuela.
• Spathanthus Desv. (2 spp.) Venezuela, Brazil, Colombia, Guyana and French Guyana.
• Stegolepis Klotzsch ex Koern. (33 spp.) - Brazil, Guyana, Panamá and Venezuela.
• Windsorina Gleason. (1 sp.) - Guyana.

Useful tips for generic identification

• Amphiphyllum Gleason - Many bracts of the inflorescence, the outer spathaceous, valvate and connate, spikelets few, sessile; the anthers opening laterally and subapical pore. Ovary with a pluriovulate carpel.
  
• Cephalostemon Schomb. - Leaves with sheaths brown, invaginating linear blades. Inflorescęncias globose; bracts linear-lanceolate, conspicuous, green; bactlets setiform, green, with attenuated apex; sepals oval; petals yellow, obovate, apex retuse and apiculate; stamens opening by subapical slit; ovary globose trilocular, uniovular carpel. Capsule with seeds oblong, non striatre, covered with a dense white papillose mass.
  
• Duckea Maguire. - Leaves with ample sheaths; linear blades. Inflorescence subglobose to cylindrical, uniflora, bracts linear-lanceolate; bractlets imbricate; sepals lanceolate, connate at base; petals included; 6 stamens with single apical pore; ovary trilocular, uniovulate carpel. Ribbed seeds.
  
• Epidryos Maguire. - Leaves with oval sheaths, invaginating, brown; blades broad-linear. Inflorescences multiple, single or with two branches; involucral bracts lanceolate, inconspicuous, imbricate; flowers yellow.
  
• Guacamaya Maguire. -Leaves with brown sheath, invaginating, with white hairs; blades green, broad-linear. Inflorescence hemispheric, solitary, red; involucral bracts connate, bivalvate; spikelets numerous patents, sessile, spiral; corolla included with the basis of the petals connate; fillaments adnate at the base, anthers bitec, biporated; ovary trilocular, pluriovulate carpel; seeds not appendiculate.
  
• Kunhardtia Maguire. - Single inflorescence; bracts bivalvate;  spikelets sessile and red, elongated, the inferior reflex; sepals free; petals lanceolate; anthers linear,  bitec; ovary with a pluriovulate carpel. Seeds piramidalis, striate, without appendages.
  
• Monotrema Koern. - Leaves with connate sheaths; linear blades. Peduncle axillary, 1-2 per axil; inflorescences small, subglobose or elongated, with 1 or 2 bracts lanceolate to ovate; petals yellow, lanceolate; dehiscence of anthers by a single apical pore; ovary pyriform, 3 locules, uniovulate carpel. Seeds oval, white, muriculate, with appendage at the apex.
  
• Phelpsiella Maguire - Inflorescence capituliform, pauciflora; Bracts orbicular-oval, margins connate, adpressed, erect; sessile spikelet; yellow flowers; ovary tricarpellate, pluriovulate carpel; anthers biporated, with rounded porous.
  
• Rapatea Aubl. - Leaves with brown or hyaline sheath; blades lanceolate or rarely linear. Inflorescence axillary, capituliforme, coplanar or elongated, free or connate spathes at the base, ovate to lanceolate, apex attenuated; spikelets numerous, pedicellate. Flowers pedicellate, sepals connate, lanceolate oval; petals connate at the base, membranous; anthers linear or oblong, 4-locular, dehiscence by terminal or subterminal pore; uniovulate carpel, placentation basal, stigma capitate, papillose. Capsule attenuated. Seeds oblong, ridged.
  
• Saxofridericia Schomb.  - Leaves with blades oblong-linear, margin aculeate, apex acute. Peduncles solitary, axillary; involucral bracts foliaceous, oval, bivalvate, sometimes connate at the margins; inflorescence globose or hemispherical; spikelets sessile; sepals free; petals obovate, the claw connate into a membrane tube; subterminal porous of the anthers, fillaments adnate to the corolla tube; ovary trilocular, pluriovulate carpel, subulate-triangular stylus. Capsule oblong -oboval.
  
• Schoenocephalium Seub. - Leaves with brown sheath; lamina linear, apex attenuated. Inflorescence capituliform;  spiklets radiate; bractlets graduate; sepals free to the base; petals lanceolate, enclosed, not open at anthesis, connate claws; 6 stamens, fillaments adnate to the corolla tube, apex cruciform, 4 porous; ovary trilocular, biovulate carpel, styles terete, truncate, minutely circumciliate. Seeds ribbed, prismatic.
  
• Spathanthus Desv. - Leaves distichous, blades linear or oblong, apex acute. Inflorescence adnate to bract, only one involucral bract, lanceolate; spikelets numerous, sessile; anthers 4-locular, dehiscing by a single apical toothed pore; ovary trilocular, two aborted carpels, style subbasal. Seed oblong-elliptic striate.
  
• Stegolepis Klotzsch ex Koern. - Robust herb; blades with sheath readily apparent, blades linear, apex acute. Inflorescence capituliform; spikelets sessile.
  
• Windsorina Gleason. - Herb glabrate, swamp. Peduncle erect, axillary; inflorescence umbellate, unwrapped; flowers pedicellate; sepals convolute; petals oval, yellow; fillets free twisted after anthesis, anther tetralocular with a subterminal pore. Capsule oval, loculicide, one seed per locule.
  

Status

• All the family is native in Neotropics, except for the genus Maschalocephalus.

General notes

• The species usually occurs in habitats with humid soil.

Important literature

Berry, P. 4004. Rapateaceae.  In: Berry, P.E., K. Yatskievych & B.K. Holst (eds.), Flora of the Venezuelan Guayana Vol. 8, pp. 413-472. Missouri Botanical Garden Press, St. Louis.

Dahlgren, R.M.T, Clifford, M.T. & Yeo, P.F. 1985. The families of monocotyledons: structure, evolution and taxonomy, pp. 391-395. Springer-Verlag, Berlin.

Givnish T.J., Millam K.C., Evans T.M., Hall J.C., Pires J.C., Berry P.E. & Sytsma K.J. 2004. Ancient vicariance or recent long-distance dispersal? Inferences about phylogeny and South American-African disjunctions in Rapateaceae and Bromeliaceae. International Journal of Plant Sciences 165: S35-S54.

Gleason, H.A. 1923. Windsorina, a New Genus of Rapateaceae. Bulletin of the Torrey Botanical Club 50(4): 147-152.

Maguire, B. 1958. Rapateaeae.  In: B. Maguire & J.J. Wurdack (eds.), The Botany of the Guayana Highland, part III. Mem. New York Bot. Gard. 10: 19-49.

Maguire, B. 1965. Rapateaceae. In B. Maguire & J.J. Wurdack (eds.), The Botany of the Guayana Highland, part VI. Mem. New York Bot. Gard. 12(3): 69-102.

Maguire, B. 1979. Additions to the Rapateaceae. Acta Amazonica 9: 267-269.

Maguire, B. 1982. Rapateaceae. In: Z. Luces de Febres & Steyermark, J.A. (eds.), Flora Venezuela 11, part II 11, pp. 85-203. Ediciones Funación Educación Ambiental, Caracas.

Seubert, M. 1847. Rapateaceae. In: Martius, C.F. Von & Urban, I. (eds.), Flora Brasiliensis. v. 3(1), pp. 125-132. Typographia regia, Munich.

Stevenson, D. W., Colella, M. & Boom, B.1998. Rapateaceae. In: K. Kubitzki, H. Huber, P.J. Rudall, P.S. Stevens & T. Stützel (eds.) The families and genera of vascular plants, Vol. 4, pp. 415-424. Springer-Verlag, Berlin.

How to cite

Monteiro, R.F. (2011). Neotropical Rapateaceae. In: Milliken, W., Klitgĺrd, 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/Rapateaceae.htm.