VI. PLUKENETIA sect. PLUKENETIA. Sajorium sect. Pluknetia Baill., Étude Euphorb. 483. 1858. TYPE: Plukenetia volubilis L. Plukenetia sect. Cylindrophora Müll.Arg., Linnaea 34: 157. 1865. TYPE: Plukenetia peruviana Müll.Arg. [= Plukenetia volubilis L.] Lianas or canopy lianas, stems slender to thick. Leaf venation palmate, primary veins 3. Inflorescences bisexual racemose thyrses (rarely racemes; usually unisexual in P.polyadenia); pistillate flowers solitary at 1–4 basal-most nodes; staminate flowers (1–) 3–15(–18)/node in condensed cymules, glomerules, or moderately condensed cymules with conspicuous and irregularly branched cyme axes (rarely 1/node). Staminate flowers: receptacle conical or globose; nectaries of interstaminal slender-cylindrical, ligulate, or small or large irregularly shaped segments (absent in P.volubilis); stamens 12–40, densely packed; filaments short-conical or slender-cylindrical, 0.5–3 mm long; pollen P = 48–60 m m, E = 53 –69 m m, tectum foveolate. Pistillate flowers: styles (20–40)70–95% connate into a cylindrical column, 5.6–13.4(–35) mm long. Fruits 4(–7)- lobed or subglobose-quadrangular capsules, dry, dehiscent or semi-dehiscent, (1.6–) 2.5–10 cm in diam, or subglobose-quadrangular berries, fleshy, indehiscent, 3.5–11 cm in diam. Seeds broadly lenticular to lenticular (ovoid or triangular-ovoid in P. polyadenia), 10–34.3(49–56) ˟ 8–27(33–37) ˟ (2.5–9) 14–36 mm (“medium,” “large,” “extra-large,” or “maximum,” sensu Cardinal-McTeague et al. 2019a). The species in this section are distributed in Mexico, Central America, northwestern and Amazonian South America, and the Lesser Antilles. Discussion —Section Plukenetia refers to subclade P3 (Fig. 1) and includes eight species distributed in the Neotropics. The section is morphologically similar to sect. Angostylidium but differs in its neotropical distribution and having cylindrical stylar columns with free style arms that are more or less uniform in thickness or tapered and erect or spreading (Fig. 3G–K). Section Plukenetia is also distinct in having staminate flowers with long slender-cylindrical filaments and interstaminal nectaries (although with short-conical filaments and without nectaries in P. volubilis), and exhibiting the widest range of fruit type (dry or fleshy, and dehiscent, semi-dehiscent, or indehiscent) and seed size (“medium” to “maximum” sized).

Published as part of Cardinal-McTeague, Warren M. & Gillespie, Lynn J., 2020, A Revised Sectional Classification of Plukenetia L. (Euphorbiaceae, Acalyphoideae) with Four New Species from South America, pp. 507-536 in Systematic Botany (Basel, Switzerland) (Basel, Switzerland) 45 (3) on page 528, DOI: 10.1600/036364420X15935294613572, http://zenodo.org/record/15466930