Neotropical Siparunaceae

Description

Dioecious or monoecious shrubs, treelets, or trees (to 40 m tall and to 120 cm in dbh).  Leaves opposite, decussate or in whorls of 3, 4, or 6, petiolate, sparsely or densely pubescent, the hairs simple, tufted, stellate, stellate-lepidote, or lepidote (peltate scales), the older leaves sometimes glabrous, the margin dentate, serrate, or entire. Inflorescences mono- or dichasial cymes, sometimes bifid or fasciculate, axillary and/or on leafless nodes.  Flowers unisexual, pedicellate, the receptacle subglobose or cup-shaped, rarely urceolate or flask-shaped, completely enclosing the carpels or stamens, at anthesis the latter protruding from a variably-sized pore in the center of the floral roof, the 4-6(-8) tepals usually small, triangular, rounded, or spatulate, or forming a rim encircling the floral cup, rarely a calyptra (S. decipiens DC.), the floral roof (velum) in female flowers sometimes differentiated into an outer bulge and an inner tube tightly sheathing the styles; stamens usually 5-9, occasionally 1 or up to 72, free, rarely their filaments laterally fused, dispersed irregularly in the floral cup except in flowers with very few stamens, the 2 pollen sacs introrse, closely adjacent, and opening by a single flap, the filaments unappendaged and undifferentiated; carpels 3-35, styles free, sometimes postgenitally fused, the stigmas papillose and decurrent. Mature fruiting receptacles fleshy and 1.5-4 cm in diam., globose, smooth, spiny, or with tubercles, rarely almond-shaped or with longitudinal ribs, often crowned by the persistent tepals, when fresh and mature reddish or yellow, with a strong pungent scent, commonly splitting irregularly from the apex and spreading to reveal the drupelets; drupelets fresh with a translucent bluish gray exo- and mesocarp and a stony endocarp, in most dioecious species drupelets bearing an apical or lateral reddish orange outgrowth of the style basis ("stylar aril"), rarely the drupelets lacking an appendage and/or the receptacle not splitting open at maturity. Germination epigeal.

Notes on delimitation

• Clearly monophyletic morphologically as well as based on chloroplast and nuclear DNA sequences.

Distribution in the Neotropics

• Distributed from Central America and the West Indies throughout northern South America to Paraguay. In lowland and montane forests to 3,800 m elev.

Distinguishing characters (always present)

• Leaves opposite, decussate or in whorls of 3, 4, or 6.
• Flowers closed, somewhat fig-like, only the style tips or anther tips emerging from an apical ostiole.

Other important characters

•   Entire plant has a lemon odour, especially when crushed (but not in herbarium material).

Key differences from similar families

• Rarely confused except Siparuna decipiens DC., which is often mistaken for Pera benensis Rusby (Euphorbiaceae).

Number of genera

One Neotropical genus: 

Siparuna Aubl.:  (at least 53 spp.) from tropical Mexico south through Central America, the Lesser Antilles, Trinidad, and northern South America to Bolivia and Paraguay.

Useful tips for generic identification

• Leaf margin (whether entire or toothed) is the best first character to distinguish a smaller set of entire-margined species, which can then be separated based on inflorescence branching and flower and fruit size.
• Whether the fruits are smooth or spiny is another easy character to use.
• Species are often difficult to identify, however.

Status

• Siparunaceae are not cultivated, with the exception of a few botanical gardens in Europe that have tried to include odd species in their warm-tropical green houses.
• No species is known to be invasive.

General notes

• This is a Neotropical family with one other genus (and species) species in Africa (Glossocalyx longicuspis Benth.), which is treated (also nomenclaturally) in the Flora Neotropica monograph cited below.
• The disjunction appears to be Gondwanan, not the result of more recent long distance dispersal.

Important literature

Renner, S.S. 2004. Monimiaceae. Pp. 252-253. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. & Heald, S.V. (eds.). Flowering Plants of the Neotropics. New York Botanical Garden, Princeton University Press, Princeton.

Renner, S.S., and Hausner, G. 1997. Siparunaceae, Monimiaceae. In: Harling, G. & Andersson, L. (eds.). Flora of Ecuador no. 59, Pp. 1-124. Department of Systematic Botany, University of Gothenburg, Gothenburg.

Renner, S. S., and G. Hausner. 2005. Siparunaceae. Flora Neotropica Monogr. no. 95, Pp. 1-256. New York Botanical Garden, Press, New York.