Neotropical Araceae

Anna Haigh

Royal Botanic Gardens, Kew, UK. 

Description

Gigantic to minute herbs, terrestrial, epiphytic, hemiepiphytic or epilithic, rarely aquatic (free-floating or rooted). Roots often aerial, in the Lemnoideae hair-like or absent. Stem aerial and erect (e.g. Dieffenbachia Schott and Rhodospatha Poepp.), creeping, subterranean and rhizomatous or tuberous (e.g. Caladium Vent. and Homalomena Schott), or appressed-climbing, frequently scandent, rarely erect, hardened, and armed (Montrichardia Crueg.), or not differentiated into stem or leaf (Lemnoideae), in this case the plant is reduced to a minute, fleshy or flattened plant body bearing hair-like roots on the undersurface or roots absent. Cataphylls often variously ribbed and persistent, may remain intact or weather into fibres. Leaves alternate, sometimes distichous, simple, basal or cauline, rarely solitary (e.g. Dracontium L.); petioles often elongate, sheathed at least basally, the apex often geniculate, blades often variegated, often oblong, cordate, sagittate to hastate, sometimes perforated, the margins entire, or pinnately to palmately lobed, main veins often radiate from petiole attachment, rarely parallel, the primary lateral veins (in some families referred to as secondary veins) pinnate, sometimes joining into collective veins along margins, the lesser veins parallel or reticulate. Inflorescences terminal or axillary, solitary or clustered in axils, an unbranched spadix (spike) subtended by a single spathe (bract), in Lemnoideae the inflorescence is within a minute dorsal cavity of the plant body (Wollfia Horkel ex Schleid., Wolffiella Hegelm.), or in paired lateral budding pouches (Spirodela Schleid., Landoltia Les & D.J. Crawford, Lemna L.); spathe herbaceous, free or adnate to spadix, spreading, reflexed or convolute, sometimes constricted below middle and differentiated into tube below and blade above, often persistent, sometimes (especially when convolute) reclosing over spadix after anthesis, the blade sometimes deciduous, green, or blade and tube of spathe differently coloured; spadix often cylindric, flowers dense, the lower part often pistillate, this part often protected by accrescent spathe tube until maturity of fruits, some parts with sterile flowers or without flowers, the upper part often staminate, this part (e.g. Syngonium Schott and Xanthosoma Schott) often caducous, the apex frequently tapered, less often clavate or ellipsoidal. Flowers sessile, small, bisexual or unisexual (the plants usually monoecious), 2-3-merous, protogynous, lacking floral bracts; perianth (=perigone) lacking in unisexual flowers; tepals 4-6, usually free, rarely united; androecium of (1-)3-6(-9) stamens, the stamens free or united into synandria, the thecae terminal or lateral, extrorse, dehiscent by longitudinal slits or apical pores; staminodes sometimes present, free or united into synandria; gynoecium syncarpous, the ovary usually superior, sessile or immersed in the spadix, often entire, rarely lobed, usually 1-3 locular, rarely more, the style usually inconspicuous, the stigma wet at anthesis, sometimes distinctly lobed; placentation axile, parietal or basal, the ovules 1-many per locule, often with funicle, less often sessile< /A> . Fruits berry-like, sometimes juicy, free or rarely fused into syncarps (Syngonium), often colourful, rarely utricles (Lemnoideae); seeds 1-many; endosperm copious to absent.

Notes on delimitation

  • The Araceae family is placed in the Alismatales together with Alismataceae and Potamogetonaceae in the Neotropics.
  • In the APG system the Araceae include the duckweeds in the subfamily Lemnoideae (formerly in a separate family Lemnaceae).

Distribution in the Neotropics

48 genera (including five introduced), ca. 3200 species worldwide.

  • Alloschemone Schott (2 species) - northern Brazil to Bolivia.
  • Alocasia (Schott) G. Don (77 species) - Old World tropics. A. cucullata (Lour.) G.Don and A. macrorrhizos (L.) G.Don are naturalized in the Neotropics.
  • Anaphyllopsis A.Hay (3 species) - tropical South America.
  • Anthurium Schott (c. 1000 species) - throughout Neotropics.
  • Asterostigma Fisch. & C.A.Mey (8 species) - Brazil to NE Argentina.
  • Bognera Mayo & Nicolson (1 species) - northern Brazil.
  • Caladium Vent.(12 species) - from Costa Rica to northern Argentina.
  • Chlorospatha Engl. (23 species) - Central America and western South America.
  • Colocasia Schott (16 species) - tropical Asia, Malay Archipelago. Colocasia esculenta (L.) Schott is cultivated and naturalized throughout the tropics.
  • Croatiella E.G.Gonç. (1 species) - Ecuador.
  • Dieffenbachia Schott (57 species) - Mexico through Central America to western and central South America, also in West Indies.
  • Dracontioides Engl. (2 species) - eastern Brazil.
  • Dracontium L. (24 species) - from Nicaragua south to Paraguay and southern Brazil, also in Trinidad.
  • Epipremnum Schott (15 species) - tropical Asia, western Pacific and North and Northeast Australia. E. aureum (Linden & André) G.S.Bunting widely cultivated and naturalized, E. pinnatum (L.) Engl. naturalized in parts of the Caribbean.
  • Filarum Nicolson (1 species) - Peru.
  • Gearum N.E.Br. (1 species) - central Brazil.
  • Gorgonidium Schott (7 species) - Peru to northern Argentina.
  • Heteropsis Kunth (14 species) - Central and South America (with a disjunct between the Amazon basin and the Brazilian Atlantic Forest Zone).
  • Homalomena Schott (107 species) - tropical Southeast Asia, Malay Archipelago, 11 species in Neotropics.
  • Incarum (1 species) - Ecuador to Bolivia.
  • Jasarum G.S.Bunting (1 species) - northern South America.
  • Landoltia Les & D.J.Crawford (1 species) - pantropical and subtropical.
  • Lemna L. (13 species) - cosmopolitan, 8 species in Neotropics.
  • Mangonia Schott (2 species) - southern Brazil to Uruguay.
  • Monstera Adans. (38 species) - Mexico to Bolivia and Brazil.
  • Montrichardia Crueg. (2 species) - Central America, northern South America and West Indies.
  • Philodendron Schott (c. 750 species) -throughout Neotropics.
  • Pistia L. (1 species) - pantropical and subtropical.
  • Rhodospatha Poepp. (27 species) - Mexico and Central America to Bolivia and eastern Brazil.
  • Scaphispatha Brongn. ex Schott (2 species) - Bolivia to Brazil.
  • Schismatoglottis Zoll. & Moritzi (106 species) - tropical & subtropical Asia, South West Pacific, 3 species in tropical South America.
  • Spathantheum Schott (2 species) - Peru to northern Argentina.
  • Spathicarpa Hook. (4 species) - tropical South America.
  • Spathiphyllum Schott (49 species) - western Pacific, Malesia. 43 species in the Neotropics.
  • Spirodela Schleid. (3 species) - cosmopolitan, 2 species in the Neotropics.
  • Stenospermation Schott (45 species) - tropical Central and South America.
  • Synandrospadix Engl. (1 species) - Peru to Northwest Argentina.
  • Syngonium Schott (33 species) - Mexico to tropical America.
  • Taccarum Brongn. (6 species) - tropical South America to northern Argentina.
  • Typhonium Schott (72 species) - tropical Africa, Arabian Peninsular to Mongolia and Australia. T. roxburghii Schott naturalized in the Neotropics.
  • Ulearum Engl. (2 species) - Peru, northern Brazil.
  • Urospatha Schott (12 species) - Central and Southern tropical America.
  • Wolffia Horkel ex Schleid. (11 species) - cosmopolitan, 5 species in Neotropics.
  • Wolffiella Helgelm. (10 species) - America, Africa, 5 species in Neotropics.
  • Xanthosoma Schott (71 species) - Mexico and Cuba to southern Brazil and northern Argentina.
  • Zantedeschia  Spreng. (8 species) - Africa; Z. aethiopica (L.) Spreng. cultivated and naturalized in the Neotropics.
  • Zomicarpa Schott (3 species) - Brazil.
  • Zomicarpella N.E.Br. (2 species) - Colombia, Peru, Northern Brazil.

Distinguishing characters (always present)

Other important characters

Number of genera

See above

Useful tips for generic identification

  • Observe venation pattern.
  • Are the flowers bisexual or unisexual?
  • Observe spathe shape, fusion to the spadix and persistence.
  • Observe presence/absence of spadix appendix.
  • Observe habit.
  • Observe leaf shape.
  • Observe presence/absence of trichosclereids.

Notable genera and distinguishing features

Anthurium:

  • The largest genus with about 1,000 species.
  • Usually an epiphyte or climbing hemiepiphyte, less often lithophyte or terrestrial.
  • Stem aerial, not tuberous or rhizomatous.
  • Petiole geniculate at apex; higher order leaf venation clearly reticulated, submarginal collective veins usually present, tissues without trichosclereids.
  • Flowers bisexual, with obvious perigone of four free tepals.
  • Spathe simple, spreading, reflexed or erect.
  • Spadix uniform in appearance with flowers of only one type.
  • Berries.
  • Throughout the Neotropics.

Philodendron:

  • About 750 species.
  • Small to gigantic.  Mostly climbing hemiepiphytes or epiphytes, sometimes arborescent to rhizomatous terrestrials.
  • Leaves with abundant resin canals.
  • Leaf blade very variable in shape, from linear to bipinnatifid, trisect or pedatisect, lacking a submarginal collective vein, fine venation parallel-pinnate.
  • Inflorescence secreting resin from spathe or spadix at anthesis.
  • Flowers unisexual, perigone absent.
  • Ovary usually 4-8-locular (extreme range 2 to 47-locular).
  • Ovules usually hemiorthotropous.
  • Placenta axile to basal.
  • Differs from Anthurium in unisexual flowers without perigone, and parallel-pinnate fine venation.
  • Throughout the Neotropics.

Status

  • Native, cultivated, naturalized and endemic taxa are found.

General notes

  • Several Aroids are cultivated for their edible tubers and leaves. These include Colocasia esculenta (L.) Schott, Xanthosoma sagittifolium (L.) Schott and some species of Amorphophallus Blume ex Decne. 
  • Some species are also used in folk medicines and as a source of fibre.
  • Aroids are widely used as ornamental plants across the world, both as house plants ands garden plants especially in the tropics.

Important literature

Bown, D. 2000. Aroids. Plants of the Arum family. 2nd edn. 392 pp. Timber Press, Portland, Oregon.

Govaerts, R. & Frodin, D.C. 2000. World Checklist and Bibliography of Araceae (and Acoraceae). 560 pp. Kew: Royal Botanic Gardens.

Mayo, S. J., Bogner, J. & Boyce, P.C. 1997. The Genera of Araceae. xii, 370 pp., Kew: Royal Botanic Gardens.

Croat, T.B. 1991. A revision of Anthurium section Pachyneurium (Araceae). Ann. Missouri Bot. Gard. 78(3): 539-855.

Croat, T.B. 1997. A revision of Philodendron subgenus Philodendron (Araceae) for Mexico and Central America. Ann. Missouri Bot. Gard. 84: 314-704.

Haigh, A., Mayo, S.J., Croat, T.B., Clark B.R. (2007). CATE ARACEAE version 0.7. Published on the internet at www.cate-araceae.org on 28 November 2008. Includes interactive keys to genera, and species of Anthurium and Philodendron.

International Aroid Society http://www.aroid.org.

Landolt, E. 1986. The family of Lemnaceae: a monographic study (vol. 1). Ver. Geobot. Inst. E.T.H., Stiftung Rübel 71: 1-566.

How to cite

Haigh, A. (2009). Neotropical Araceae. 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/Araceae.htm.