Pandaceae

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Pandaceae

Description

Dioecious, evergreen shrubs to generally small trees; Leaves simple, distichous; Stipules triangular, small, (late) caducous. Inflorescences axillary fascicles in Microdesmis or terminal (Galearia) or cauliflorous racemes (to panicles) (Galearia, Panda); Flowers small, 5-merous, usually shortly pedicellate; Fruits drupes, thin- or thick-walled, surface smooth to ribbed or angular to pustular. Seeds compressed, cotyledons thin, oily;

Distribution

in continental South East Asia, Malesia and the Solomon Islands: present in tropical West Africa, continental South East Asia and West Malesia: present tropical West Africa: present
The family comprises three genera, of which the monotypic Panda occurs in tropical West Africa, Galearia (5 species) is found in continental South East Asia, Malesia and the Solomon Islands, and Microdesmis (10 species) is disjunct in tropical West Africa, continental South East Asia and West Malesia.

Taxonomy

The family was generally regarded as part of the Euphorbiaceae s.l. (Webster 1994; Radcliffe Smith 2001), and classified in the subfamily Acalyphoideae, tribe Galearieae. Forman (1966) was the first to realise that Panda resembled Microdesmis and especially Galearia (up to then only the latter two were combined in the tribe Galearieae by Bentham 1880). It is one of the small groups that has been moved inside and outside the Euphorbiaceae s.l. (Radcliffe-Smith 1987). Engler & Gilg (1912) even introduced the order Pandales with as sole family the Pandaceae. Molecular research (Wurdack et al. 2004) divided the Euphorbiaceae s.l. into five families, with the Pandaceae separate. Morphological differences between the Euphorbiaceae in a narrower sense and the Pandaceae were already known, like the narrower rays in the wood, the lack of an obturator in the seeds and a columella in the fruits (Euphorbiaceae have wider rays, possess an obturator and a columella in the fruit). In a way the drupaceous fruits are also different, because the vast majority of the Euphorbiaceae has capsules, but genera and species with drupes exist, also within the subfamily Acalyphoideae (e.g., several species of Mallotus).

The monotypic, West African Centroplacus was formerly included in this family, but is nowadays regarded as a separate family, Centroplacaceae. It differs in the inflorescences being cymes, a disc in the pistillate flowers, and capsular fruits. Wurdack et al. (2004) show it to be sister to the Pandaceae, but with low bootstrap support.

The Pandaceae are generally difficult to identify and often confused with the Flacourtiaceae (this family is nowadays divided over the Salicaceae and Achariaceae). Galearia has the same kind of distichous, asymmetric leaves as many genera in the Flacourtiaceae (but the latter lack the terminal inflorescences and show many differences in flower structure). Microdesmis is generally confused with Flacourtia and Casearia and Microdesmis magallanensis was even placed in the Oleaceae under Worcesterianthus. The family lacks simple diagnostic characters and is generally identified via the generic level, because Galearia with its long terminal or cauliflorous racemes and Microdesmis with its petaloid flowers in fascicles are normally easily recognised.

Citation

Forman - in Kew Bull. 1966: 309
Meijer - in Bot. Bull. Herb. Forest Dept. Sabah. 1968: 233
in Kew Bull. 1980: 220
G.L.Webster - in Ann. Missouri Bot. Gard. 1994: 67
Airy Shaw - in Kew Bull. 1972: 362
in Kew Bull. 1982: 36
in Kew Bull. 1975: 220
Radcl.-Sm., Gen. Euphorbiacearum. 2001: 125
Pax - in Engl. & Harms, Pflanzenfam., ed. 2, 19c. 1931: 171
Engl. & Gilg, Syllabus, (ed. 7). 1912: 223
in Kew Bull. 1981: 365
Pax & K.Hoffm. - in Engl., Pflanzenr. IV. 1911: 96
G.L.Webster - in Bot. J. Linn. Soc. 1987: 6