International Aroid Society

33. Syngonium yurimaguense Engler, Bot. Jahrb. Syst. 38:141. 1905. TYPE: Peru, Loreto, Yurimaguas, Vie 9237 (B, holotype; K, isotype).

Hemiepiphytic vine; stem 1-1.5 cm diam., the epidermis becoming brown, flaking; petioles slender, sheathed to upper 2/3, about as long as or to 3 times longer than the blade, 24-36 cm long, the sheath briefly free-ending and acute, the unsheathed portion acute adaxially; blades thin, trisect, the leaflets conspicuously free; median leaflet ovate-elliptic to oblong-elliptic, bluntly acute to gradually acuminate at the apex, obtuse to acute and attenuate at the base, 11-23 cm long, 4.5-9 cm wide; primary lateral veins 4-7 pairs, at least part of them departing the midrib at 90° angle, then arcuate or almost straight to the collective vein; tertiary veins distinct; primary collective vein distinct, 2-6 mm from the margin, generally more or less straight; lateral leaflets generally somewhat narrower, acuminate or narrowly acute on the inner margin at the base, hastate lobed on the outer margin, the auricles 2-5 cm long, acute to narrowly rounded at the apex.
Inflorescences 1-2 per axil, the prophylls slender; peduncles ca. 6.5 cm long at anthesis, less than 3 mm diam. (dried); spathe 9-10 cm long; spathe tube oblong-elliptic, 3-3.5 cm long, ca. 1.5 cm diam., probably green; spathe blade oblong-elliptic, acuminate at the apex, white (fide Engler, 1877), pistillate portion of the spadix 2 cm long, 1 cm diam. (dried), the pistils depressed-globose; staminate portion of the spadix clavate, ca. 5 cm long, 7 mm diam. (dried), the sterile flowers irregular, 1-1.5 mm diam., broadest in the direction of the axis, the fertile flowers irregularly 4-5-sided, completely fused into a synandrium with no sign of fusion, the apex truncate, margin irregularly scalloped.
Infructescences creamy yellow, subglobose, 5.5 cm long, 4.5 cm diam.; peduncle to 2 cm long; seeds black, 4-5 mm long. Figs. 79, 80.

DISTRIBUTION: Syngonium yurimaguense is known from Brazil, Ecuador, Peru, and Bolivia at elevations of 50 to 700 m.
It is closely related to S. atrovirens from western Venezuela but differs in having the spathe tube conspicuously constricted below the blade. Syngonium yurimaguense shares with S. atrovirens moderately thin leaves which have the medial lobe bearing veins which depart the midrib at almost a 90° angle. In other species of Syngonium the primary lateral veins depart the midrib at an acute angle.

BOLIVIA: PANDO: Cobija, Rio Acre, Vie 9237 (K).
BRAZIL: No other location, Burchell 9859 (K). AMAZONAS: N of Ribeirao, Prance et al. 6278 (INPA, NY, US).
ECUADOR: NAPO: N of Puyo, Croat 49660 (MO).
PERU: cuzco: Paucartambo, Vargas 13426 (US). LORETO: Yurimaguas, Vie s.n. (B). MADRE DE DIOS: Province of Manu, Terborgh 6739B (F).