SYNGONIUM LATERINERVIUM
PROTOLOGUE: Syngonium laterinervium , published in Annals of the Missouri Botanical Garden 68: 620 (1982).
Syngonium laterinervium Croat, sp. nov. Caudex scandens haud glaucus, internodiis 2–8 cm longis, 5–10 mm diam.; foliorum petiolus 10–20 cm longus, vaginatus praeter 1–3 cm distale, lamina trisecta, segmentum medium oblongum-ellipticum, leviter inaequalaterum, (5.5–)8–17 cm longum, 2.3–5.5 cm latum, apice acuminatum, mucronulatum, basi acutum ad attenuatum, segmenta lateralia (5.2–)9–14 cm longa, 2.5–4 cm lata, oblonga-elliptica, inaequalatera basi auriculata; folia venis lateralibus utroque latere 4–6, nervis parvis vix prominioribus, subangulo ca. 10–20°. Inflorescentia pedunculo 4.5 cm longo, in axilla solitarius; spathae tubus ca. 3.5 cm longus, 1.2 cm diam., anguste ellipticus, extus viridis pallidus; spathae lamina ca. 5 cm longa, alba. Type: Costa Rica, Puntarenas, Osa Peninsula, Corcovado National Park within 2 km of park headquarters at Sirena, below 200 m, 8°29'N, 83°36'W, Liesner 2951 (MO-2588405, holotype).
DISTRIBUTION: SW. Costa Rica to W. Panama: Costa Rica, Panama.
DISTRIBUTION NOTE: Costa Rica: Puntarenas Panama: Chiriquí, Panamá Province.
SPECIES DESCRIPTION:
Nomadic vine; juvenile stages not seen. Adult plants with scandent stems, much branched; internodes 2–8 cm long, 5–10 mm wide, green, drying light brown, the periderm often flaky in small patches. Leaves with petioles 10–22 cm long, sheathed 75–95% their length; sheath free-ending and narrowly acute at apex, often glaucous in lower half, those petioles subtending inflorescences much broader in lower half; free portion between petiole and blade flattened adaxially; blades trisect, leaflets overlapping or not distinctly free from one another; median leaflet oblong-elliptic, somewhat inequilateral, (5.5)8.0–22.0 cm long, 2.3–7.6 cm wide, acute and cuspidate to narrowly acuminate at apex, obtusely cuneate to attenuate at the base; lateral leaflets oblong-elliptic, very inequilateral, narrowly acute to attenuate on inner margins at base, conspicuously auriculate on outer margins at base, usually joining petiolule at ca. 90°, the petiolules 4–10 mm long, sulcate adaxially, margin continuous with margin of both median and lateral leaflets, the auricles about as long as or longer than broad, 12–28 cm long, oblong to triangular, rounded at the apex; midrib weakly sunken on upper surface, raised beneath; primary lateral veins 4–6 per side, slightly more conspicuous than the smaller lateral veins, all the veins below clearly visible, departing the midrib at ca. 70°, spreading almost straight to the collective vein; collective veins 2 or 3, the principal one 2–5 mm from the margin.³
INFLORESCENCE:
Inflorescences solitary; peduncle 2.5–4.5(4.8) cm long, ca. 3 mm diam., erect at anthesis, glaucous; spathe ca. 8.5 cm long, the tube narrowly ellipsoid, ca. 3.5 cm long, 1.2 cm diam., outside pale green, greenish yellow or pinkish red outside, dark red or purple inside; spathe blade elliptic, ca. 5 cm long, acuminate at the apex, white; spadix 6.7–9.0 cm long; pistillate portion of the spadix 1.8 cm long, ca. 9 mm diam., the flowers irregularly hexagonal, stigmas flat at the apex, 1.5–2.0 mm diam.; staminate portion of the spadix ca. 5 cm long, clavate, ca. 1.5 cm diam. at the broadest point in the upper 1/3, fertile staminate flowers mostly rhombic to sometimes irregularly hexagonal at apex, surface minutely rugose, margins weakly crenate. Infructescences with syncarp creamy yellow. Flowers have been found in Mar, May–July, October Fruits December.³
ECOLOGY:
Syngonium laterinervium is known from southwestern Costa Rica and northwestern Panama in Tropical wet forest life zones in the region surrounding Golfo Dulce, at elevations ranging from near sea level (50 m) to 600 m. .³ altitude: 0–600 m
ETYMOLOGY:
From Latin latus (lateris), "side," and nervus, "vein." The original description does not explain the name; it most likely refers to the few, widely spaced primary lateral veins that Croat used to separate the species.²
NOTES:
1. The species is a member of sect. Syngonium and is characterized by its scandent, much branched adult stems, elongate, light brown-drying internodes with flaky periderm, petioles sheathed to near apex, the sheath free-ending and narrowly acute at apex, free portion flattened adaxially, by its trisect and petiolulate blades, the oblong-elliptic leaflets with the outer margins conspicuously auriculate, 4–6 primary lateral veins per side, a solitary short-pedunculate inflorescence, spathe tube narrowly ellipsoid, pale green and the clavate spadix. It is most easily confused with Syngonium hoffmannii but differs in having the lateral veins departing the midrib at no less than ca. 70° and in having the primary lateral veins only slightly more prominent than the lesser lateral venation. Syngonium hoffmannii has at least the lower primary lateral veins departing the midrib at a much sharper angle (ca. 50°), and much more conspicuous than the minor lateral veins (drying much darker than the surface).³
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Syngonium laterinervium
2. Annals of the Missouri Botanical Garden 68: 620 (1982) — protologue.