Syngonium triphyllum Birdsey ex Croat

Juvenile plants at first with short internodes (5 mm or less), becoming scandent, not glaucous, green to greenish brown, turning brown with age; internodes to 17 cm long; petioles sheathed 4/5 or nearly their entire length, less than 10 cm long, the sheath with the margin crisped; blades inequilateral, elliptic, acuminate at the apex, acute to obtuse and often inequilateral at the base, sometimes weakly cordate, 6–23 cm long; 3–9 cm wide. Intermediate plants with petioles 14–28 cm long; blades entire and elliptic to oblong-elliptic or ovate-elliptic or becoming auricle-lobed at the base, the auricles held parallel to the petiole, in later stages becoming more trisect, the lobes oblong-elliptic, directed at nearly right angles to the midrib. Adult plants with stems not glaucous, sometimes branched; internodes to 9 cm long, to 2.5–3.5 cm long on flowering portions, 1–2.5 cm diam., brown, matte, sometimes drying flaky, sometimes with sharp longitudinal wrinkles; petioles 11–50 cm long, sheathed 2/3–4/5 their length or more, the unsheathed portion sharply triangular with the lateral margins sharply raised; blades usually trisect but frequently with a conspicuous spatulate auricle at the base, the auricle sometimes to 15 cm long, the blade thus appearing almost 5-pedatisect; leaflets free, semiglossy above, dark green, drying dark, the lower surface slightly paler; median leaflet ovate to elliptic or oblong-elliptic, equilateral or nearly so, 17–32 cm long, 6–14 cm wide, short-acuminate at the apex, cuneate or obtuse at the base; lateral leaflets of well-developed blades 15–28 cm long, 4–11 cm wide, ovate-elliptic to elliptic, nearly equilateral to very inequilateral and variously auriculate at the base, the auricles oblong to spatulate to oblong-elliptic, 6–16 cm long; primary lateral veins 10–16 pairs, scarcely more prominent than the interprimary veins, the latter numerous, the primary, major secondary veins and collective veins prominently sunken, prominently raised on the lower surface, the smaller veins clearly visible when fresh; reticulate veins often very close and fine on drying, the collective veins 3–12 cm from the margin, moderately straight or broadly arching between the primary lateral veins. Inflorescences 1–5 per axil, usually 1–3, most frequently 1 or 2; peduncles erect, 5–7 cm long in flower, 8–13 cm long and pendent in fruit; spathe ca.14 cm at anthesis; spathe tube narrowly ellipsoid, 4.5–6 cm long, 2–2.5 cm diam., pale green outside, red inside to near the apex; spathe blade oblong-elliptic to oblong, white on both sides, short cuspidate and weakly cucullate at the apex, 8–9 cm long, ca. 3.5 cm diam. (to 5 cm wide when flattened); pistillate portion of the spadix 1.9–2.5 cm long (fresh) (11.8 cm long dry), 7–13 mm diam., pale yellowish white, the flowers irregularly 4-sided, the stigma sessile, cup shaped; staminate portion of the spadix 6–10 cm long, 1–1.5 cm diam., clavate, gradually attenuate toward the sterile flowers, the fertile staminate flowers 4-staminate, the anthers partially or completely fused, the synandrium truncate or slightly rounded at the apex, the staminate sterile flowers slightly longer than the adjacent fertile staminate flowers and much longer than the pistillate flowers, 4–6-sided to ellipsoid or subglobose; the spathe tube becomes rolled backward along its lateral margins and the fleshy white spadix is prominently displayed against the bright red interior of the spathe tube. Infructescences oblong-elliptic, green tinged with purple, becoming violet purple on the outside, the inner surface bright red; spadix oblong-ellipsoid, 6–8 cm long, 3.54 cm diam.; mesocarp white, fleshy, sweet; seeds black, irregularly ovoid to ellipsoid, 5–8 cm long, 4–6 cm wide.

Discussion: Syngonium triphyllum ranges from the northern Atlantic coast of Honduras to central Panama. It also occurs on the Pacific slope at Palmar Norte in Puntarenas Province, Costa Rica, and on the Burica Peninsula between Panama and Costa Rica. It no doubt occurs as well on the Osa Peninsula in Costa Rica. It is probably restricted to premontane wet forest and tropical wet forest below 1000 m. Birdsey (1955) reported the species to be in virgin areas in Honduras but from disturbed areas in Costa Rica. I have always found it growing in virgin forest or in disturbed remnant virgin forest but never in a weedy situation. The species may be recognized by having leaves with numerous conspicuously sunken veins, by drying almost black, and by having juvenile blades with small, more or less spatulate lateral lobes that are directed laterally. Other distinguishing characters include the cucullate spathe blade, the sessile cup﷓shaped stigma, and the petiole cross﷓sectional shape which has an acute medial rib and conspicuously raised lateral margins. According to Birdsey (1955) the pollen of S. triphyllum is unique for Syngonium with the "surface almost completely covered with more or less orbicular knobs." Inflorescences have been found from February through May and in October and November. Immature fruits are known from March to October with nearly mature fruits in May, June, and July.