International Aroid Society

14. Syngonium steyermarkii Croat, sp. nov. TYPE: Guatemala, San Marcos, vicinity of San Rafael, Finca Armenia at La Trinidad, ca. 2 km above main buildings offinca, 1100-1250 m, virgin forest along stream, Croat 40842 (MO-2599645, holotype; EAP, F, MEXU, PMA, US, USCG, VEN, isotypes).

Caudex haud glaucus, scandens, internodiis 2-4 cm longis, 1-3 cm latis; foliorum petiolus 25-60 cm longus, ca. ad Vi longitudinalis usque vaginatus; lamina incisus lobo, ambito ovata, 20-43 cm longa, 17-36 cm lata, lobus anticus segmentis 5-6, 2-5 cm latis. Inflorescentia in axilla 1-7, pedunculus 7-13 cm longus; spathae tubus 2.6 cm longus, 2 cm latus; pedunculus et spathae tubus valde glaucus.
Hemiepiphytic creeper; sap milky; stems 1-3 cm diam., 1.3 m long; upper internodes 1.5-2.5 cm long, dark green, shiny, drying light brown, shiny, the periderm drying wrinkled; leaves ca. 8, persisting only near the apex, broadly spreading; petioles 25-60 cm long, subterete, sheathed to beyond the middle to upper 2/3, sharply ribbed near the apex of the sheath, drying black; blades incised-lobate, ovate in outline, 20-43 cm long, 17-36 cm wide, firmly membranous, medium green above, paler beneath, drying black, the anterior lobe with 5 or 6 segments, shallowly lobed to within 1-2 cm distant from the midrib, the segments 2-5 cm wide, narrowly rounded at the apex, the posterior lobes about half as long as the anterior lobe, the segments partly confluent; midrib and primary lateral veins sunken above, raised and U-shaped beneath; secondary veins and collective vein weakly sunken on the upper surface, weakly raised on the lower surface; tertiary veins distinctly visible.
Inflorescences 1-7 per axil; peduncles terete, erect in flower, 7-13 cm long, ca. 1 cm diam., straight to sigmoid; spathes 5.5-7 cm long, somewhat fleshy, narrowly ovoid, acuminate, tightly inrolled and curved forward at the apex, scarcely constricted near the middle, opening from the apex of the spadix to the base of the spadix; spathe tube green, glaucous, grayish or whitish green, ca. 2.6 cm long, 2 cm diam.; spathe blade green, scarcely or not at all flared open; spadix 5-5.5 cm long; pistillate portion of the spadix 2.6-3 cm long, 2 cm diam., broader than the staminate portion, the pistillate flowers pale green, 4-5 mm diam., the stigma sessile, ca. 2 mm diam., orange yellow; staminate portion of the spadix 2-2.5 cm long, 0.6-1.3 cm diam., the staminate flowers creamy white, the synandrium truncate at the apex with a medial depression, irregularly 4-6 sided, 2-3 mm diam.
Infructescences with the spathe tube 6-7 cm long, 3.5-4 cm diam., in part weakly glaucous, obtusely ribbed on the closed side; fruiting spadix 5-7 cm long, ca. 4 cm diam. Figs. 31, 37-39.

DISTRIBUTION: Syngonium steyermarkii is known only from the Pacific slope of Guatemala and southeastern Mexico at elevations above 1250 m.
The species is named in honor of Julian A. Steyermark who made three collections of it between 1940 and 1942 in three different departments of Guatemala.
Syngonium steyermarkii is unique in having incised-lobate leaves like those of Philodendron radiatum Schott. It also differs from other Syngonium species in having the inflorescences all mature at about the same time and having the pistillate part of the spadix appreciably larger than the staminate portion.
The data on the flowers was provided by Josef Bogner from a living collection of Croat 47201 growing at Munich. The type collection had immature fruits in July.

GUATEMALA: QUEZALTENANGO: Between Finca Pirineos and Patzulin, Standley 86886, 86900 (F); Along Quebrada Geronimo, Finca Pirineos, S slope of Volcan Santa Maria, 1300-2000 m, Steyermark 53437 (F). SAN MARCOS: Finca El Porvenir along Rio Chopal, S slope of Volcan Tajumuico, 1300-1500 m, Steyermark 37499 (F); Above San Raphael, Croat 40842 (MO). SUCHITEPIQUEZ: Volean Santa Clara between Finca El Naranjo and upper slopes, 1250-2650 m, Steyermark 46621 (F).
MEXICO: CHIAPAS: N ofPuente Monte Peria, Croat 47201 (MICH, MO).