Neotropical Dichapetalaceae

Description

Trees, shrubs, lianas, or suffruticose subshrubs. Stipules present but usually caducous, sometimes fimbriate.  Leaves simple, alternate, entire, pinnately veined. Inflorescence corymbose-cymose of subcapitate, or the flowers fasciculate, axillary or more frequently attached to the petiole or rarely to the midrib. Flowers small, hermaphrodite or less frequently unisexual, actinomorphic to weakly zygomorphic; pedicels often articulated. Petals 5, either free, imbricate and almost equal, or connate into a tube, with lobes equal or markedly unequal, lobes usually bifid at apex and frequently bicucullate or inflexed; often clawed at base. Stamens 5, all fertile or only 3 fertile, free or adnate to the corolla tube, with filaments or rarely anthers sessile; anthers bilocular, dehiscing longitudinally. Disc of 5 equal or unequal hypogynous glands alternating with stamens, or united into a disc. Ovary superior, free, 2-3, locular, ovules anatropous, pendulous, paired at top of each loculus. Styles 2-3, free or more frequently connate nearly to apex, often recurved, stigma capitate or simple.  Fruit a dry or rarely a fleshy drupe; epicarp most frequently pubescent; mesocarp thin; endocarp hard; 1-2 (-3) locular, loculi usually with only one seed developing; seed pendulous, without endosperm; embryo large, erect.

Notes on delimitation

• The family has been variously placed, often in the Euphorbiales.
• Cronquist placed it in the Celastrales near to the Icacinaceae.
• Recent molecular work shows that it belongs in the Malpighiales and is very close to the Chrysobalanaceae, Trigoniaceae and Euphroniaceae.

Distribution in the Neotropics

• A tropical family of about 240 species in three genera, distributed throughout the lowland tropical regions of both hemispheres (but absent from Polynesia and Micronesia), extending into the subtropics in Africa and India.

Distinguishing characters (always present)

• The inflorescence is often borne on the petioles and rarely on the midrib.
• The petals are usually two-lobed and cucullate and dry black.
• Fimbriate stipules occur in some species of Dichapetalum Thouars.
  

Number of genera

• Three: Dichapetalum, Stephanopodium Poepp. & Endl., Tapura Aubl.

Useful tips for generic identification

Key to genera of Neotropical Dichapetalaceae

1.  Petals free and regular; stamens free; inflorescence with a long distict peduncle.... Dichapetalum
1.  Petals connate or only 3 free; stamens adnate to corolla tube; inflorescence sessile or almost so ... 2

2.  Corolla with 5 equal obtuse lobes, shorter than tube; fertile stamens 5, anthers sessile on tube ...   Stephanopodium
2.  Corolla zygomorphic, lobes bifid and bicucullate, exceeding tube in length; fertile stamens 3 or 5, anthers on slender filaments ...Tapura

Status

• Stephanopodium is endemic to the Neotropics.
• Dichapetalum and Tapura also occur in the Old World tropics.
• All three genera are native to the Neotropics.

General notes

• Some species are poisonous, especially to cattle.

Important literature

Prance, G. T. 1972. Monograph of Dichapetalaceae. Flora Neotropica 10: 1-84.

Prance, G. T. 2001. Dichapetalaceae. Flora de Colombia 20: 1-62.