Neotropical Araliaceae

Pedro Fiaschi*and Gregory M. Plunkett**

* Universidade de São Paulo, São Paulo, Brasil.
** New York Botanical Garden (NYBG), USA. 

Description

Small shrubs to large trees, less commonly lianas or herbs, glabrous or pubescent. Plants terrestrial, hemi-epiphytic, or climbing. Leaves alternate, frequently heteroblastic; petioles often sheathing at the base, sometimes alate, exstipulate, or with ligulate stipules; blade simple to ternately, palmately or pinnately lobed or compound (or peltate), with entire, crenate, toothed, or incised margins; venation pinnate or palmate. Inflorescences terminal (rarely axillary), paniculate, compound-umbellate or simple -umbellate, the ultimate units umbellate or capitulate, sometimes racemose or spicate. Flowers hermaphroditic, staminate, or pistillate, epigynous, actinomorphic. Perianth parts typically (4)-5-(10). Calyx lobes simple and minute or obscure, forming a truncate rim. Petals valvate or imbricate, sometimes calyptrate, the bases broadly inserted. Stamens isomerous, alternipetalous, anthers dorsifixed, introrse, dehiscing by longitudinal slits; filaments inflexed in bud. Ovary syncarpous of 2-5-(12) carpels, each carpel unilocular with apical placentation; stigmas on a style or sessile; styles free or connate, sometimes confluent with the nectiferous disc of the ovary. Ovules anatropous, pendulous, one per locule, unitegmic, crassinucellate or rarely tenuinucellate. Fruits simple or sometimes multiple, fleshy (rarely dry), usually drupaceous or baccate with a fleshy mesocarp and a separate, variously sclerified endocarp (pyrene) around each locule, or rarely a schizocarp with two mericarps. Seeds straight; endosperm copious, oily, uniform or variously ruminate; embryo minute but well-differentiated.

Notes on delimitation

  • Recent studies have suggested the transfer of a few herbaceous genera traditionally placed in Apiaceae (e.g., Hydrocotyle L. and Trachymene Rudge) to the mostly woody Araliaceae (Plunkett et al. 1996, Plunkett et al. 2004b). As a result, the approximately 75 species of Hydrocotyle found in the Neotropics are now referred to Araliaceae.

Distribution in the Neotropics

  • Aralia L. - most species in seasonally dry forests, usually below 500 m.
  • Dendropanax Decne. & Planch. - moist forests at lowland to mid-elevation areas, usually below 1500 m; centers of diversity in Jamaica, southern Central America, northern South America, and eastern Brazil.
  • Hydrocotyle - widespread in moist habitats, especially in the Andes.
  • Oreopanax Decne. & Planch. - most species in mountainous areas of Central and South America, especially above 1500 m in the Andes; 2 spp. in eastern Brazil.
  • Schefflera J.R.Forst. & G.Forst. - most species in moist habitats at mid to high-elevations, up to 3000 m. Infrageneric groups (Frodin 1995) are well-correlated with geographic areas: "Cephalopanax" in Andean areas above 2000 m, ranging from southern Venezuela to Peru; "Cotylanthes" from southern Central America to northern Ecuador, with an eastern extension to the Venezuelan coastal mountains; "Crepinella" with most species endemic to the "tepuis" of the Guayana Shield and the Amazonian white-sand lowland areas; "Didymopanax" mostly in low to mid-elevation areas of eastern Andean South America, especially in Brazil and southern Venezuela; and "Sciodaphyllum" with most species in the tropical Andes and in southern Central America, the Caribbean Islands, and the western part of the Guayana Shield.

Distinguishing characters (always present)

  • No characters are always present in Araliaceae. However, the presence of flowers usually grouped in umbels or capitula and nectariferous discs is useful for recognizing members of the family.

Other important characters

  • The woody plants are often sparsely branched with pachycaulous stems.
  • The leaves are often clustered toward apex of branches, with petioles of rather unequal lengths (especially in Dendropanax), and bases sometimes sheathing.

Number of genera

  • 5 genera: Aralia (8 spp.), Dendropanax (~75 spp.), Hydrocotyle (~75 spp.), Oreopanax (~85 spp.) and Schefflera (~300 spp.).

Useful tips for generic identification

Notable genera and distinguishing features

  • Aralia - the only genus with spinose species in the Neotropics.
  • Hydrocotyle - the only herbaceous genus in the Neotropics.

Status

  • Aralia is native.
  • Dendropanax is native.
  • Hydrocotyle is native, but is also represented by several introduced species.
  • Oreopanax is native and endemic to the Neotropics.
  • Schefflera has both native (ca. 300) and cultivated (ca. 5) species.
  • Cussonia Thunb., Fatsia Decne. & Planch., Hedera L., Panax L., Polyscias J.R.Forst. & G.Forst., Tetrapanax K. Koch and Trevesia Vis. each have one or a few species cultivated in the Neotropics.

General notes

  • Three other genera of the family, Oplopanax (Torr. & A. Gray) Miq., Panax L. and Pseudopanax K. Koch, are native to the Americas, but all are found exclusively in temperate areas.
  • Additional generic names have commonly been applied to some Neotropical taxa of Araliaceae, such as Gilibertia Ruiz & Pav. (under Dendropanax), Crepinella Marchal, Didymopanax Decne. & Planch. and Sciodaphyllum P. Browne (under Schefflera), and Coudenbergia Marchal, Pentapanax Seem. and Sciadodendron Griseb. (under Aralia).

Important literature

BORSCHSENIUS, F. 1997. Oreopanax (Araliaceae) in Ecuador. Nordic Journal of Botany 17(4): 373-396.

CANNON, M. J. & CANNON, F. M. 1989. Central American Araliaceae - a precursory study for the Flora Mesoamericana. Bull. Brit. Mus. (Nat. Hist.), Bot. 19: 5-61.

FIASCHI, P. & PIRANI, J.R. 2007. Estudo taxonômico do gênero Schefflera (Araliaceae) na Região Sudeste do Brasil. Bol. Bot. Univ. São Paulo 25: 95-142.

FRODIN, D.G. 1989. Studies in Schefflera (Araliaceae), IV. Synopsis of the Formenkreis comprised of Didymopanax attenuatus (Sw.) Marchal and allied species, with nomenclatural changes. Proc. Acad. Nat. Sci. Philadelphia 141: 313-319.

FRODIN, D.G. 1995. Neotropical montane Araliaceae: an Overview. In S.P. Churchill, H. Baslev, E. Forero & J.L. Luteyn (eds.) Biodiversity and Conservation of Neotropical Montane Forests. New York Botanical Garden, New York, p. 421-430.

FRODIN, D.G. 1997. Araliaceae. In J. A. Steyermark, P. E. Berry & B. K. Holst (eds.) Flora of the Venezuelan Guayana vol. 3. Missouri Botanical Garden, St. Louis, p. 1-31.

FRODIN, D.G. 2004. Araliaceae. In N. Smith, S. A. Mori, A. Henderson, D. W. Stevenson & S. V. Heald (eds.) Flowering Plants of the Neotropics. Princeton University Press, Princeton, p. 28-31.

FRODIN, D.G. & GOVAERTS, R. 2003. World Checklist and Bibliography of Araliaceae. Royal Botanic Gardens, Kew.

MACBRIDE, T.F. 1959. Flora of Peru: Araliaceae. Field. Mus. Nat. Hist., Bot. Ser. 13: 9-43

MAGUIRE, B., STEYERMARK, J.A. & FRODIN, D.G. 1984. Araliaceae, p. 46-82. In B. Maguire, R.S. Cowan, J.J. Wurdack & collaborators. The Botany of the Guayana Highland - Part XII. Mem. New York Bot. Gard. 38: 1-84.

MARCHAL, E. 1878. Hederaceae. In C.F.P. von Martius & A.G. Eichler (eds.) Flora brasiliensis. Typographia Regia, Monachii, vol. 11, pt. 1, p. 229-258, tab. 66-71.

MATHIAS, M.E. 1936. The genus Hydrocotyle in northern South America. Brittonia 2: 201-237.

MATHIAS, M.E., & CONSTANCE L. 1951. Supplementary notes on South American Hydrocotyle. Bull. Torrey Bot. Club 78: 300-309.

PLUNKETT, G.M., SOLTIS, D.E. & SOLTIS, P.S. 1996. Higher level relationships of Apiales (Apiaceae and Araliaceae) based on rbcL sequences. American Journal of Botany 83: 499-515.

PLUNKETT, G.M., CHANDLER, G.T., LOWRY II, P.P., PINNEY, S.M. & SPRENKLE, T.S. 2004a. Recent advances in understanding Apiales and a revised classification. South African Journal of Botany 70: 371-381.

PLUNKETT, G.M., WEN, J. & LOWRY II, P.P. 2004b. Infrafamilial classifications and characters in Araliaceae: Insights from the phylogenetic analysis of nuclear (ITS) and plastid (trnL-trnF) sequence data. Plant Syst. & Evolution 245: 1-39.

PLUNKETT, G.M., LOWRY II, P.P, FRODIN, D.G. & WEN, J. 2005. Phylogeny and geography of Schefflera: pervasive polyphyly in the largest genus of Araliaceae. Ann. Missouri Bot. Gard. 92: 202-224.

How to cite

Fiaschi, P. & Plunkett, G. (2009). Neotropical Araliaceae. 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/Araliaceae.htm.