Peraceae

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Peraceae

Description

Trees or shrubs, in Clutia also shrublets or woody herbs, dioecious (or monoecious in some Clutia and Pera). Leaves alternate, often distichous, (to very rarely opposite in Pera), simple, entire, penninervid, often pellucid-punctate, eglandular. Stipules small or absent. Inflorescences axillary fascicles (or also short panicles or thyrses in Pogonophora), pistillate flowers in Clutia often solitary, usually bracteate or in Pera flowers involucrate and buds even completely enclosed by the 2 involucre-like bracts. Flowers small, actinomorphic, unisexual, pedicellate or sessile. Fruits rhegmas, dehiscing septicidally and partly loculicidally into 2-valved mericarps except almost drupaceous in Pera and tardily also completely dehiscing loculicidally, in Pera mericarps remaining attached to the persistent columella; Seeds ellipsoid to globular, black, shiny, always carunculate;

Distribution

Africa: present Neotropical: present Pantropical: present S and SE Asia: present Southern America: W Africa: present W Malesia: present all tropics and subtropics of S and C America: present tropical South America: present
The family is pantropical. Five genera are distinguished: Chaetocarpus (c. 13 spp.) occurs in all tropics and subtropics of S and C America, Africa and S and SE Asia with 1 species in W Malesia; Clutia with c. 75 species is African; Pera with 30-40 species is present in the Caribbean and tropical South America; Pogonophora has 2 neotropical and one W African species; and Trigonopleura Hook.f. is found with 3 species in W Malesia.

Taxonomy

The most recent classification of the Euphorbiaceae s.l. (APG III 2009) divides it into five families (Euphorbiaceae s.s., Pandaceae, Phyllanthaceae, Picrodendraceae, Putranjivaceae) with a note on the possible split off of the Peraceae, the most basal clade in the phylogeny of the Euphorbiaceae s.s. (e.g., Wurdack et al. 2005, Tokuoka & Tobe 2006). Phylogenetic analyses (Davis et al. 2007) of 111 Malphigialies (plus 22 outgroups) for eight DNA markers attached the Rafflesiaceae at the base of the Euphorbiaceae (s.s.), just above the Peraceae clade. Including the Rafflesiaceae in the Euphorbiaceae (s.s.) would, on the one hand, render one of the few extremely recognisable families, Rafflesiaceae, unrecognisable and, on the other hand, it would add inferior ovaries with many ovules per locule to the description of the Euphorbiaceae, making them extremely indistinguishable. Therefore, it is prudent to split off the genera at the base of the Euphorbiaceae cladogram as a separate family, the Peraceae. Then the Rafflesiaceae and Euphorbiaceae (s.s.) remain monophyletic. Also positive is that the Peraceae have a typical character combination: woody, dioecious (rarely monoecious), leaves simple, entire and without any glands, unisexual flowers generally in axillary fascicles, ovaries mainly 3-locular with one anatropous ovule per locule, fruits with usually 3 conspicuously shiny black seeds, and the testa of the seeds with a tracheoidal exotegmen. Because of the monophyly of the Euphorbiaceae and the recognisability of the Peraceae we accept the family for Flora Malesiana. The Peraceae are part of the Malphighiales and sister to the Euphorbiaceae (s.s.) together with Rafflesiaceae.

We refrain from an infrafamily classification for two reasons. Maintaining the four tribes as in the classification of the Euphorbiaceae s.l. (Webster 1994, Radcliffe-Smith 2001) of which three tribes are monotypic and only one contains two genera (Chaetocarpeae with Chaetocarpus and Trigonopleura) is over the top for such a small family. Moreover, the backbone phylogenies of the Euphorbiaceae (Wurdack et al. 2005, Tokuoka & Tobe 2006) do not include representatives of all genera and this makes a subclassification premature. Webster (1994) and Radcliffe-Smith (2001) used the four tribes as the position of the genera in their classifications was still uncertain.

Citation

Racl.-Sm., Gen. Euphorbicearum. 2001: 114
G.L.Webster - in Ann. Missouri Bot. Gard. 1994: 63
Asch. - in Ann. Missouri Bot. Gard. 1994: 64
Radcl.-Sm., Gen. Euphorbicearum. 2001: 115
Racl.-Sm., Gen. Euphorbicearum. 2001: 117
G.L.Webster - in Ann. Missouri Bot. Gard. 1994: 65
Asch. - in Ann. Missouri Bot. Gard. 1994: 64
Racl.-Sm., Gen. Euphorbicearum. 2001: 112