Syngonium sparreorum Croat, Ann. Missouri Bot. Gard. 68(4): 639. (1982).
Hemiepiphytic vine; stem 1–1.5 cm diam., drying pale brown; internodes elongate, 6–7 cm long near the apex; petioles 29–47 cm long, narrowly sheathed 1/2 –2/3 their length, to 7.5–10 cm from the apex, the apex of the sheath slightly free from the petiole; blades trisect to 5-pedatisect, the leaflets distinctly free; median leaflet equilateral, elliptic to obovate-elliptic, abruptly acuminate at the apex, cuneate to acute at the base, 17–28 cm long, 9.5–12 cm wide, the leaf tissue decurrent to near the base, the lateral leaflets slightly inequilateral, obtuse to acuminate at the apex, 14–25 cm long, 5.3–9 cm wide, the base narrowly acute on the inner side, obtuse to rounded or conspicuously auriculate on the outer side, the auricles conspicuously constricted at their base; petiolules 7–17 mm long, sometimes free; outermost leaflets nearly oblong to ovate-oblong, 8–10 cm long, 2.7–7 cm wide, narrowly rounded to acute at the apex, the blade surfaces drying yellowish brown; primary lateral veins mostly 10–12 pairs, mostly joining the midrib at a nearly 90 degree angle, curved to the collective vein; collective vein 3–10 mm from the margin, almost straight or conspicuously loop-connecting with the primary lateral veins; reticulate veins very fine and close but clearly visible on dried material. Inflorescences 2 in uppermost leaf axil, erect; prophylls ca. 15 cm long, obtuse at the apex, apparently caducous; peduncles 7–10 cm long, slender, 2–4 mm diam. (dried); spathe tube 5–6 cm long, oblong-ovoid, 1.5–2 cm diam.; spathe blade 7.5–8.5 cm long, ovate when open, cuspidate at the apex, thinly coriaceous, drying brown, soon caducous; pistillate portion of the spadix 10–12 mm long, 5 mm diam. (dried), the flowers ca. 1.5 mm diam., in 5 or 6 spirals, the stigmas raised, ca. 1 mm diam.; staminate portion of the spadix 6–7.5 cm long, clavate, ca. 1cm diam. in the widest part, conspicuously constricted just above the sterile staminate flowers, the fertile staminate flowers ca. 3 mm long, rounded to irregularly 4–6-sided, the apex of the synandrium truncate, entire, the margins minutely crenulate; sterile staminate portion of the spadix ca. 14 mm long, ca. 8 mm diam. the sterile staminate flowers ca. 2.5 mm long, 1.5 mm diam., mostly free from one another, rarely fused. Infructescences pendent; peduncle to 13 cm long, to 7 mm diam.; spathe tube oblong-ellipsoid, gradually tapered to both ends, to 13 cm long and 5 cm diam., apparently dark violet purple; fruiting spadix oblong-ovoid, to 9.5 cm long on the front side, 6.5 cm long on the back side, ca. 4.5 cm diam.; seeds black, oblong-ovoid ca. 7 mm long.
Type: Ecuador, Cotopaxi, RRo Guapara, ca. 20 km NW of El Corazón, monsoon forest, ca. 250 m, Sparre 17193 (S. holotype).
Cotopaxi: Río Guapara NW of El Corazón, 250 m, Sparre 17096, 17101, 17193, 17212, 17297 (S).