International Aroid Society

24. Syngonium macrophyllum Engler, Pflanzenr. IV. 23E (Heft 71): 128. 1920. TYPE: Mexico (locality not known) (B, holotype, two specimens made from cultivated plants in Berlin).

Juvenile plants with glaucous stems (at least in the northern extreme of its range); petioles 7-25 cm long, sheathed ca. 1/2 their length; blades subcoriaceous, broadly ovate, 8-16 cm long, 6-10 cm wide, the posterior lobes at first rounded, becoming sagittate, rounded at the apex; intermediate leaves with the apical lobe elliptic, acuminate at the apex, much constricted at the base, the posterior lobes becoming nearly pinched off, narrowly rounded to acute at the apex. Adult plants with stems glaucous (or possibly not in Panama) 3-4 cm diam., usually not branched and appressed to trees; internodes 1-4 cm long near the apex; petioles often glaucous, 25-60 cm long, sheathed 1/2-3/4 their length with a weak to prominent rib between the sheath and the blade, the sheath free-ending and acute at the apex; blades subcoriaceous, pedatisect; leaflets 7-9, mostly free or the outer ones confluent, the lowermost usually variously auriculate, this soon pinched off to form a leaflet, dark to medium green on the upper surface, smooth, the lower surface light green; rachis sharply margined; median leaflet oblanceolate, elliptic, broadly elliptic or ovate-elliptic, acuminate to acute and down-turned at the apex, cuneate to abruptly attenuate at the base, 17.7 cm long, 5-18 cm wide; primary lateral veins 3 or 4 pairs in the median leaflet, weakly sunken above, raised below.
Inflorescences 4-8 per axil; peduncles almost terete, glaucous in the northern part of the range, erect, 10-13 cm long at anthesis, 14-20 cm diam. and pendent in fruit; spathe tube ovate, green and glaucous outside, green to greenish tan inside, 3-5.5 cm long, 3-5 cm diam.; spathe blade 7-11.5 cm long, at first green, becoming cream, mucronate at the apex; pistillate portion of the spadix 1.5-3 cm long, ca. 2 cm diam. at the base, tapered to the apex, to 1.5 cm diam. at the apex, pale green, the flowers irregularly 5-6-sided, the stigma subsessile, discoid, yellowish at anthesis; staminate portion of the spadix oblong-ellipsoid, abruptly constricted just above the sterile staminate flowers, the fertile staminate flowers with 4 stamens, the synandrium with the line of fusion scarcely visible, the apex truncate or with a conspicuous central depression, the sterile staminate flowers somewhat larger. Infructescences often rather massive, 8-14 cm long, 5-8 cm wide, yellow and pruinose in the northern part of the range; syncarp narrowly ovoid to subglobular, 6-10 cm long, 3.5-6 cm wide, brown; mesocarp sweet smelling, fleshy; seeds obovoid, white before maturity, becoming dark gray, 1.4-1.8 cm long, ca. 1.5 cm wide. According to natives in Guatemala near Puerto Barrios, the spathe tube of the mature infructescence turns yellow, whereas in Panama immature fruits have been seen turning a pale brick red. Figs. 50, 51, 54-56, 61.

DISTRIBUTION: Syngonium macrophyllum ranges from Mexico to Ecuador (Pacific slope only). Collections from Rio Palenque Field Station reported by Dodson & Gentry (1978) as S. podophyllum are also this species. I believe the latter species is restricted to the other side of the Andes.The species is known from wetter parts of tropical moist forest, premontane wet forest and tropical wet forest and ranges from sea level to 1100 m. It is most common below 700 m. In Panama the species is always found in good forest or along roads recently opened. While this is usually the case also in the remainder of its range, to the north one finds the plants frequently in more disturbed areas. However, in most cases it is possible that plants could have persisted in the areas where they were collected from earlier forest disturbances.
It is possible that the Panamanian plants from central Panama (chiefly west of the Isthmus on Santa Rita Ridge, the Pipeline Road, El Llano-Carti Road, etc.) represent a distinct species. These collections (e.g., Croat 13952) differ in having only a few primary lateral veins, mostly restricted to the basal half of the blade. Panamanian plants do not have glaucous parts and tend to have somewhat smaller leaves with narrower segments than do collections made from the northern part of the range.
Syngonium macrophyllum is not usually confused with any other species and is distinguished by its large parts, smooth, subcoriaceous, 7-9-pedatisect leaves and by its ovate-cordate juvenile blades. It may be confused with S. podophyllum in some parts of Panama and Costa Rica where they both occur in wetter parts of tropical moist or premontane wet forests.
Flowers and fruits are found throughout the year but principally from June to August.
COLOMBIA: CHOCO: E of Quibdo, Forero & Jaramillo 2637 (COL); Valley of Rio San Juan near Docordo, Forero et al. 4351, 4546 (MO); E of Yuto, Gentry & Renteria 24372 (MO).
COSTA RICA: ALAJUELA: Vicinity of Laguna Hule, Luleyn 3228 (DUKE, MO); Between Canas and Upala, Burger & Baker 9883 (F), Croat 36332, 36339, 36400. 36479, 36491 (MO). HEREDIA: Near Puerto Viejo, Croat 35721 (MO); S of Hone Creek on road to Bribri, Croat 43183 (MO).
ECUADOR: No other location, Eggers 15131, (F, GH, NY, US). ESMERALDAS: S of Esmeraldas, Sparre 15498 (S); San Lorenzo, Jativa & Epiing 724 (NY, UC), 738, 830 (UC). GUAYAS: Vicinity of Naranjito, Camp E-3584C, 3584B (NY). IMBABURA: Between Ibarra and Lita, Croat 38917 (MO). LOS RI'OS: Rio Palenque Field Station, Croat 38677 (F, MO), Gentry 9986 (MO); Between Babahoyo and Montalve, Sparre 17961 (S). PICHINCHA: Santo Domingo Alluriquin, Sparre 14790 (S).
GUATEMALA: ALTA VERAPAZ: Between Campur and Socoyo, Croat & Folsom 33986 (F, MO), Standley 91929 (F); Cubilquitz, Steyermark 44397 (F); Pantin, Standley 70551 (F). IZABAL: Near Entre Rios, Standley 72782 (F); S of Puerto Barrios, Croat 41805 (MO).
HONDURAS: ATLANTIDA: Lancetilla Valley, Chickering 82, 160 (MICH). COPAN: E of Copan, Croat 42528 (MO).
MEXICO: CHIAPAS: N of Isthuatan, Croat 47867 (MO); SE of Palenque, Croat 40140 (MO).
NICARAGUA: CHONTALES: Above Cuapa, Stevens 3665 (MO). ZELAYA: Along Cano Majagua, Stevens 6997 (MO); SW ofColonia Naciones Unidas, Stevens 4985 (MO); Road to Colonia Yolania and Colonia La Esperanza, Stevens 6372 (MO); Road to Panua, Stevens 7797 (MO); Road from Siuna to Matagalpa, Stevens 7458 (MO).
PANAMA: BOCAS DEL TORO: Road between Almirante and Qjo del Agua, Croat 38217 (MO);
Forest above Milla 7.5, Croat & Porter 16242 (MO). CANAL ZONE: Pipeline Road, Croat 16699 (MO, SCZ). COLON: Santa Rita Ridge Road, Croat 34352 (MO); Between Tonosi and Rio Indio, Croat 33534 (MO). DARIEN: Santa Fe, Duke 14259 (MO). PANAMA: Vicinity ofCerro Campana, Croat 35964 (MO); El Llano-Carti Road, Croat 25187 (AAU, MO, PMA); Logging roads along Rio Pita, Duke 4746 (BH, GH, MO, US). SAN BLAS: Rio Ada, Sugden 625 (MO).