Christenh., M.F.Fay & M.W.Chase
Petenaea cordata (from northern Central America) was first described in Elaeocarpaceae and later placed in Tiliaceae, but most authors have been uncertain about its familial affinities. It was considered a taxon incertae sedis in the Angiosperm Phylogeny Group classification (APG III). Molecular analyses based on a recent collection from Guatemala indicate a distant, weakly supported sister-group relationship to the African genus Gerrardina (Gerrardinaceae; Huerteales). As no obvious synapomorphies exist for Gerrardina and Petenaea, the new monogeneric family Petenaeaceae was proposed. The polymorphic order Huerteales now comprises four small families: Dipentodontaceae, Gerrardinaceae, Petenaeaceae and Tapisciaceae. Petenaea cordata is the only species in the genus Petenaea.
Trees to c. 10 m, or large shrubs. Stems often tinged red, villous-tomentose. Leaves minutely stipulate; petioles 5–11 cm, densely short villous, red; blades 8.5-15.5 × 6.5-14.5 cm, chartaceous, densely villous below, glabrescent above, turning red with age, palmately veined at base with 5-7 primary veins, the secondary venation reticulate, the base broadly cordate, the margins minutely denticulate, the apices acute to broadly short-acuminate. Stipules minute, soon caducous. Inflorescences axillary, cymose, long-pedunculate, rose-pink, the branches villous-tomentose; pedicels 5–12 mm, pink. Flowers with the sepals c. 4 mm, valvate, lanceolate, attenuate from the base to the apex, reflexed, reddish pink, the base bearing 2-3 obovoid subsessile glands, and densely villous with hairs c. 2 mm, moniliform, pink; petals absent; disc annular, glandular; stamens 8-12, glabrous, the anthers yellow, opening by an apical pore-like slit; ovary superior, sessile, tomentose; style slender; stigma discoid. Berry 6–12 mm, shallowly 4-5 lobed, ovoid to subglobose, pulpy, sweet, sparsely pubescent; seeds numerous, c. 1 mm, oblong-pyramidal or irregular. Flowering and fruiting continuously.
- Maarten J. M. Christenhusz fls, Michael F. Fay fls, James J. Clarkson, Peter Gasson fls, Julio Morales Can, Jorge B. Jiménez Barrios, Mark W. Chase fls (September 15, 2010). "Petenaeaceae, a new angiosperm family in Huerteales with a distant relationship to Gerrardina (Gerrardinaceae)". Botanical Journal of the Linnean Society. 164 (1): 16–25. doi:10.1111/j.1095-8339.2010.01074.x.