SYNGONIUM STEYERMARKII
PROTOLOGUE: Syngonium steyermarkii , published in Annals of the Missouri Botanical Garden 68: 604 (1982).
Syngonium steyermarkii Croat, sp. nov. Caudex haud glaucus, scandens, internodiis 2–4 cm longis, 1–3 cm latis; foliorum petiolus 25–60 cm longus, ca. ad ½ 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. Type: Guatemala, San Marcos, vicinity of San Rafael, Finca Armenia at La Trinidad, ca. 2 km above main buildings of finca, 1100–1250 m, virgin forest along stream, Croat 40842 (MO-2599645, holotype; EAP, F, MEXU, PMA, US, USCG, VEN, isotypes).
DISTRIBUTION: Mexico (Oaxaca, Chiapas) to SW. Guatemala: Chiapas, Guatemala, Mexico Southeast, Mexico Southwest, Oaxaca.
DISTRIBUTION NOTE: Guatemala: Guatemala, Quetzaltenango, San Marcos, Suchitepéquez Mexico: Chiapas, Oaxaca.
SPECIES DESCRIPTION:
Nomadic vine; appressed-climbing,; 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, periderm drying wrinkled; leaves ca. 8, persisting only near apex, broadly spreading. Leaves with petioles 25–60 cm long, subterete, sheathed to beyond middle to upper 2/3, sharply ribbed near apex of 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, anterior lobe with 5 or 6 segments, shallowly lobed to within 1–2 cm from midrib, segments 2–5 cm wide, narrowly rounded at apex, posterior lobes about half as long as anterior lobe, segments partly confluent; midrib and primary lateral veins sunken above, raised and U-shaped beneath; secondary veins and collective vein weakly sunken on upper surface, weakly raised on lower surface; tertiary veins distinctly visible.³
INFLORESCENCE:
Inflorescences 1–7 per axil; peduncle terete, erect in flower, 7–13 cm long, ca. 1 cm diam., straight to sigmoid; spathe 5.5–7.0 cm long, somewhat fleshy, narrowly ovoid, acuminate, tightly inrolled and curved forward at apex, scarcely constricted near middle, opening from apex of spadix to base of 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 5.0–5.5 cm long; pistillate portion of spadix 2.6–3.0 cm long, 2 cm diam., broader than staminate portion, pistillate flowers pale green, 4–5 mm diam., stigma sessile, ca. 2 mm diam., orange-yellow; staminate portion of spadix 2.0–2.5 cm long, 0.6–1.3 cm diam., staminate flowers creamy white, synandrium truncate at apex with a medial depression, irregularly 4–6 sided, 2–3 mm diam. Infructescences with spathe tube 6–7 cm long, 3.5–4.0 cm diam., in part weakly glaucous, obtusely ribbed on closed side; syncarp 5–7 cm long, ca. 4 cm diam. The type collection had immature fruits in July.³
ECOLOGY:
Syngonium steyermarkii is known only from the Pacific slope of Guatemala and southeastern Mexico at elevations above 1250 m. .³ altitude: 1250 m
ETYMOLOGY:
Named in honor of Julian A. Steyermark (1909–1988), the American botanist who made three collections of it between 1940 and 1942 in three different departments of Guatemala, during his fieldwork for the Flora of Guatemala.²
NOTES:
1. Syngonium steyermarkii is the only Central American species in Section Pinnatiloba and 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 species was named in honor of Julian A. Steyermark who made three collections of it between 1940 and 1942 in three different departments of Guatemala. The data on the flowers in the 1982 revision of Syngonium was provided by Josef Bogner from a living collection of Croat 47201 growing at Munich. However, Pedro Díaz Jiménez (Díaz et al., 2023) has collected what he believes is Syngonium steyermarkii in Oaxaca, Mexico, but his plant has remarkably different inflorescences. On the other hand, the leaves are very similar. Nevertheless, these differences need to be pursued. Either the plant that Bogner flowered (from a cutting from the Croat type collection) had a radically deformed nature or the plant that Díaz collected is perhaps a different species. To my knowledge no other flowering plant of the original collection has been reported.,³
2. Recorded from Oaxaca (Santa María Yucuhiti) in March 2022, more than 500 km from the Chiapas localities that were previously the only Mexican records; the inflorescences of that plant developed normally, with closed spathe tubes on young infructescences, suggesting that the open-tubed inflorescence described from cultivated material was malformed.⁴
STORY:
STORY TITLE: The inflorescence in the books may have come from a deformed plant
Syngonium steyermarkii is the odd one out in its genus: the only species whose adult leaves are pinnately lobed, and the sole member of section Pinnatiloba. Julian Steyermark first collected it, sterile, in three Guatemalan departments in 1941 and 1942, and Thomas Croat described it in 1981 from Guatemalan material, taking living plants to St. Louis in 1977 and on to Munich, where they flowered.²
The flowering plant that Croat described was strange even for a strange species. In his account, and again in a mid-1980s Aroid Profile with Josef Bogner, the spathe tube is open to the base and stays open after flowering, and the pistillate part of the spadix is swollen until it fills the tube. There was, in other words, no pollination chamber at all, and on that architecture Croat and Bogner predicted that the species must be pollinated by something other than the large scarab beetles that visit its relatives.
In March 2022 Pedro Díaz Jiménez and colleagues, working on palms and cycads at San Isidro Paz y Progreso in Santa María Yucuhiti, Oaxaca, found the species more than 500 km in a straight line from the nearest Mexican record, which until then had been Chiapas alone. Among the adults was a fertile plant, and its inflorescences developed in the ordinary sequential way, with well-formed spathes and, on the young infructescences, a spathe tube that was completely closed. The inflorescence description in the literature had been made from the cultivated Munich plant rather than from a fertile specimen collected in the field, and the authors, citing Croat's own view, concluded that it may have been based on malformed inflorescences. They ask for other populations, including the type locality, to be examined before the point is settled.⁴
The species remains barely known. Fewer than a dozen specimens exist in herbaria; the only Guatemalan collections are Steyermark's and Paul Standley's from more than eighty years ago and Croat's from more than forty, and the isotype Croat cited for the herbarium of the University of San Carlos could not be found there and may be lost. It grows in cloud forest and high evergreen rainforest between 1200 and 2000 m on the Pacific slopes from the Sierra Madre del Sur to the Sierra Madre de Chiapas; in Oaxaca it was growing in disturbed forest alongside Anthurium schlechtendalii, Monstera siltepecana, Monstera tacanaensis and Philodendron purulhense.⁴
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Syngonium steyermarkii
2. Annals of the Missouri Botanical Garden 68: 604 (1982) — protologue.
Additional photos by Patrick Blanc
Additional photos from iNaturalist by Ubaldo Edgar García López and R.E.Llanos